SA Roofing September 2014 | Issue: 63

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SEPTEMBER 2014 ISSUE: 63

SA R36 EACH INCL. / R360 PER ANNUM INCL.

ROOF INSULATION SPACER

(Prov. Patent No: 2014/1404)

Roof Insulation Spacer/Packer

Insultrak™ is a roof insulation spacer system designed specifically for use with faced flexible fibre roof insulation materials in over-purlin roof applications.

Insultrak™ is manufactured from a lightweight high density closed cell rigid foam and supplied in standard dimensions as required for the relevant thickness of insulation.

By being used as a packer between the insulation and the roof sheet, Insultrak™ provides the necessary spacing to allow the insulation to attain maximum installed thickness in the application, and significantly reduces backward pressure on the roof sheet or clip system.

Due to the fact that Insultrak™ is manufactured from a highly efficient insulation material, it further enhances the thermal value of the final system and negates thermal bridging which may occur with other types of materials.

Insultrak™ has the following value added benefits: • Ultra lightweight – adds no mass to the structure • Excellent thermal value – Thermal Conductivity (K-Value) 0.024 W/m°C • 100% Closed cell structure – impervious to moisture or water absorption • High density – 32-36kg/m³ • High compressive strength - 160-310 kPa depending on thickness • Fire tested and approved for use in the required application • Can be combined with other approved roof insulation materials to improve thermals

Application Methodology The Insultrak™ spacers are simply laid over the insulation on top of the purlin before fixing of the roof sheet, or clip system for secret fix roof sheeting.

The roof is then fixed down in the standard method applied for the relevant roof sheet with the addition of longer fixing screws to accommodate the packer. Insultrak™ is supplied in standard 3m lengths which are 75mm wide and available in the following thicknesses: 25mm; 40mm and 75mm.

Alternative thicknesses may be produced upon request.

Concealed Fix clip

Roof sheet

Thickness

Compressive Strength

Standard Length

Insulation Thickness

25mm

160kPa

3 metre

50mm - 75mm

40mm

190kPa

3 metre

100mm - 135mm

75mm

340kPa

3 metre

150mm +

Insultrak™ Fire Performance

Purlin

Insulation

Insultrak™ has been fire tested according to the SANS 428 application test for over-purlin roof insulation systems with an A1 fire rated faced fibre and found not to present a fire risk or support flame spread.

(Report available upon request) E-mail: info@insultrak.co.za | Tel: 012-800 3606 | Fax: 012-800 3835

www.insultrak.co.za | www.roofinsulation.co.za

Dezzo Roofing specialises in manufacturing and supplying a lightweight steel roof support system, specifically designed to carry all roof coverings including concrete roof tiles, steel sheeting and fibre cement sheeting. Almost any roof design can be accommodated and each roof is custom engineered and designed.

ALL THE RIGHT MOVES WHEN CHOOSING INSULATION 21

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THE RIGHT CHOICE FOR INTELLIGENT ORGANS. MOVE TO BLOCK 25

23

24 YOU DID NOT USE LAMBDABOARD

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19

18

12

11

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SUPERIOR LONG TERM R-VALUE. MOVE TO BLOCK 16

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16 HIGH COMPRESSIVE STRENGTH. ADVANCE TWO BLOCKS

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LAMBDABOARD IS AESTHETICALLY PLEASING

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8 MOISTURE AND WATER RESISTANT. MOVE TO BLOCK 14

YOU DID NOT USE LAMBDABOARD

1

7

6

THERMOSET, DOES NOT MELT, DRIP OR SPREAD FLAME

8

2

START

YOU ALWAYS WIN WITH LAMBDABOARD

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REDUCES ENERGY USAGE IN A BUILDING. MOVE TO BLOCK 25

YOU DID NOT USE LAMBDABOARD

25

4

5

ENVIRONMENTALLY FRIENDLY & RECYCLABLE

AUTOMATICALLY ADVANCE TWO BLOCKS

Sometimes making the simplest choices makes all the difference to the environment.

Lambdaboard is the eco-friendly choice when it comes to insulating your home,

office, building or warehouse. Lambdaboard offers the highest levels of insulation at an affordable price without damaging the environment. Use Lambdaboard today!

TM

H O M E

•

B U I L D I N G

•

R E F R I G E R AT I O N

w w w. l a m b d a b o a r d . c o m

•

I N D U S T R I A L

QUALITY AND INNOVATION Our roofing systems protect thousands of homes, commercial and industrial buildings. Achieving a good looking product is not sufficient in competitive global markets. It is attention to detail in the manufacturing process that has earned our roofing systems an international reputation for excellence.

PRODUCTS

TRADE ENQUIRIES

• DURA “V” Tile • Corrugated Profile (S-rib) - Galvanised and Colour Coated • Widespan Profile - Galvanised and Colour Coated • Bullnosing and Cranking - Galvanised and Colour Coated • Roofing accessories • Roll Formed Sections • DURATRUSS - light weight stell trusses

tel: 031 940 4484

|

email: info@steelworld.co.za

Steelworld ensures its highest standards in quality and aesthetic appeal keeps in line with Steelworld hallmark in quality and innovation.

www.duraworld.co.za

EXTRAORDINARY CHOICE A Fusion of technology in 7 layers for strength and protection The quality roofing solutions that saves you time and money

IF IT DOES NOT SAY “D” IT’S NOT A DURAROOF TILE

PRODUCTS

TRADE ENQUIRIES

Products

Export

• DURATILE • DUROMA • DURASPAN • DURA V TILE

• DURATILE • DUROMA • DURASPAN • DURA V TILE • Roofing accessories

tel: 031 940 4484

|

email: info@duraroof.co.za

DURAROOF ensures its highest standards in quality and aesthetic appeal keeps in line with DURAROOF hallmark in quality and innovation.

www.duraroof.co.za

SEPTEMBER 2014

ISSUE: 63

EDITOR’S COMMENTS....................................................................................................... 6

Trademax Publications

CONTRIBUTORS................................................................................................................. 8

SA Roofing

AWARDS......................................................................................................................... 12-16 COVER STORY.............................................................................................................. 18-19

Tel: 0861 SA ROOF

INDUSTRY INSIGHT.................................................................................................... 20-26

Tel: 0861 727 663 Cell: 082 266 6976

FASTENING SYSTEMS................................................................................................. 30-34

Fax: 0866 991 346

NEWS..................................................................................................................................... 36

www.trademax.co.za

PROJECT FE ATURE..................................................................................................... 38-43

Postnet Suite 241

EVENTS.................................................................................................................................. 44

Private Bag X103

PRODUCT PROFILE..................................................................................................... 46-47

7463

N1 City

HOT DIP GALVANIZING........................................................................................... 48-53 NEWS..................................................................................................................................... 55

PUBLISHER:

SOL AR PV............................................................................................................................ 56

Billy Perrin billy@trademax.co.za 0861 727 663 EDITOR: Jennifer Rees editor@trademax.co.za 0861 727 663 ADVERTISING: Jacqui Marsh jacqui@trademax.co.za 0861 727 663 LAYOUT & DESIGN: Craig Patterson craig@trademax.co.za SUBSCRIPTIONS: Belinda Thwesha belinda@trademax.co.za 021 595 3422

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DISCLAIMER The views expressed herein are not necessarily those of Trademax Publications. Although we have done our best to ensure the accuracy of our content, neither Trademax Publications nor SA Roofing magazine will be held liable for any views expressed or information disseminated in this issue.

SEPTEMBER 2014

EDITOR’S COMMENTS

Brains and brawn In this issue of the SA Roofing magazine, we feature not only the more technical aspects of roofing, but also the aesthetic side of this imperative component of construction.

W

e feature the beautiful Cradlestone Mall, a winner in the commercial division of the 9th Saint-Gobain Gypsum International Trophy awards, as well as two attractive local commercial roofing projects that showcase steel roofing’s capacity, not only to be used innovatively in smart design, but to add serious aesthetic appeal to any structure.

Furthermore, we delve into the various issues surrounding the hot dip galvanizing of sheet metal, including pointers on the correct storage, treatment and fastening methods of this everpresent material.

Welcome to the September issue of the SA Roofing magazine.

Enjoy the read.

We bring to our readers more information from prominent industry experts on the legalities surrounding erected timber roof structures and offer important details around appropriate fastener selection for a specific job. These are necessary components of any roof structure that might very well not be visible, but their importance cannot be overstated.

Jen

Upcoming Events INTERBUILD AFRICA

SAISC STEEL AWARDS 2014

MBSA ANNUAL CONGRESS

20-23 AUGUST 2014 | EXPO CENTRE, NASREC, JOHANNESBURG

18 SEPTEMBER 2014 | JOHANNESBURG, CAPE TOWN AND DURBAN

21-23 SEPTEMBER 2014 | PORT ELIZABETH

View www.interbuild.co.za for more info

View www.saisc.co.za for more info

View www.mbsacongress.co.za or more info

Energy Efficient. On Time & On Budget Ensure your housing project is energy efficient - with Eco-Insulation

Meet the requirements of SANS 10400 XA by specifying EcoInsulation as thermal and acoustic insulation of choice above the ceiling, or pumped in under a flat roof. SABS Approved.

ENERGYMC

• SABS Approved • Fire Rated - B/B1/2 - SANS 10177- P5 • Sustainable - recycled and green

• 100% coverage of area - no cold spots • Professionally installed - on time, on budget • Exceptional performance - R-values

Company of the Year Excellence Award - S.A. Energy Efficiency Association

PPC Certificate

www.eco-insulation.co.za

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tel - 021 555 3766

SEPTEMBER 2014

LIGHT GAUGE STEEL The low mass per m2 (between 2-10kg) of this roofing system ensures both savings on the supporting structure as well as on transportation and erection costs whilst also being vermin proof and non-combustible.

Large sections of the roof can simply be pre-assembled on the ground and hoisted into position on the walls – making this one of the most viable systems with a large range of applications up to a clear span of 40m.

Supported through a substantial network of licensed truss suppliers, Ultra-Span is equally ideal for all local and export applications where it can be pre-assembled or site assembled.

The non-combustible solution.

MiTek Park,754 16th Road, Randjespark, Ext. 34, Halfway House,1685. Midrand (Head Office) Tel: + 27(0) 11 237 8700 Cape Town Tel: 021 905 0244 • Durban Tel: 031 700 6332 • Port Elizabeth Tel: 041 581 7525 email: marketing@mitek.co.za • www.mii.com/southafrica *MiTek

Industries South Africa (Pty)Ltd, a division of the worldwide MiTek Group.

creating the advantage

CONTRIBUTORS

Contributors LYNDSAY COTTON Lyndsay entered the construction industry in 1989 and has many years’ experience in both the civil and commercial spheres of this industry. He is well versed in residential construction and especially roofing, as he erected many of the roof structures in over 300 luxury houses and upmarket units in residential clusters he constructed. Holding a BSc (QS) degree, and a Diploma in Project Management, Lyndsay is the General Manager of a leading Gauteng-based fabricator, and is the current Chairman on the board of the ITC-SA. Although work always takes a priority, his passion is exploring the back roads of Africa on a KTM990 Adventure motorcycle.

REITZE HYLKEMA Reitze has been the Managing Director of Kare Industrial Suppliers for the past 20 years and has been involved in the marketing of fastening systems for over 30 years. He is actively involved with the Corrosion Institute of Southern Africa and the Southern African Light Steel Frame Building Association and is also a participating member of various technical committees at the SABS relating to roofing, fasteners and corrosion. He feels strongly about “fit-for-use” quality in all construction materials, especially in roofing, and for him, educating the market is imperative. His hobbies include scuba diving and CrossFit training.

FINISHING TOUCH The highest quality roof tiles at a cost effective price that enhances any building construction, only from the Technicrete Double Roman and Tuscan Roof Tiles Accessories:

Available in:

• • • • •

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Tapered ridge tile Angle butt ridge tile Butt mono ridge tile Angle collar ridge tile Hip starter tile

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Colour variations Various styles and finishes Quality installation

paving | masonry | roof tiles | erosion protection retaining walls | drainage | kerbs | precast products

Technicrete is a trading division of ISG, a leading supplier of innovative infrastructure products to the construction and mining markets in Southern Africa.

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Tel: 086 126 6267 www.technicrete.co.za

ISO 9001: 2008 certified SABS mark on applicable products

SEPTEMBER 2014

AWA R DS

Cradlestone Mall wins international award South African drywall and plastering craftsmanship is on par with international standards 12

SEPTEMBER 2014

AWA R DS

T

he 9th Saint-Gobain Gypsum International Trophy awards took place in Berlin, Germany, on Friday, 6 June 2014. Cradlestone Mall was named the winner in the Commercial section of the global awards.

Cradlestone Mall, designed by architects, Bentel & Associates, is situated on the edge of The Cradle of Humankind in Muldersdrift, Gauteng. This project combines innovation and sustainability, showcasing how Saint-Gobain Gyproc’s high performance plasterboard systems and plasters, combined

SEPTEMBER 2014

with skilled workmanship provides solutions for high quality, safe, comfortable, modular and sustainable interiors across a wide variety of applications.

The main feature of the shopping mall is the ceiling above the food and entertainment area, where the installation of the ceiling was designed to contour the jagged shape of the ‘armadillo-style’ roof, which is framed by three dimensional bulkheads, giving the mall its angular expression.

13

AWA R DS

The architects’ challenging slanted design inspired by the layering of strata as a unique design theme, coupled with high acoustic and aesthetic specification, lead to the selection and installation by contractor, Abbeycon (Pty) Ltd., of Gyproc products and systems. The products used included Gyproc Moisture Resistant, Gyproc FireStop, DONN T38 & T37 grids, Gyproc Gypex White and Fissured Ceiling Boards, RhinoGlide Plaster and Gyproc Gyptone BigLine6.

Saint-Gobain Gyproc products used in the walls and ceilings were, in addition, instrumental in improving the energy saving qualities of the structure.

The international panel of judges commended the unique shape of the structure’s roofline, coupled with the flawless finishes, which are exposed to extreme light, and its high level of acoustic performance is what made this bold project a winner in their eyes.

The Cradlestone Mall project was one of 87 projects entered into the global awards, from a total number of 33 countries across the globe.

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SEPTEMBER 2014

ENERGY EFFICIENT ROOF PERFORMANCE Specifications that reveal project cost-saving benefits

CLIMATIC ZONE MAP Masina Makhado Phalaborwa Polokwane

Nelspruit

Pretoria Centurion Midrand Soweto Johannesburg Vereeniging

Mmabatho

2

Bloemfontein

St Lucia

Ulundi

Kimberly

Port Nolloth

Zone 1

Kroonstad Welkom Virginia

Upington Alexander Bay

Kruger National Park

Richards Bay

Pietermaritzburg Durban

Drakensburg

The type of roof insulation used plays a vital role in reducing the flow of heat transfer within a building. The correct specification significantly impacts on the compliance of the SANS 204 standard, Energy Efficiency in buildings. It also effects the project expenses such as handling, storage, labour and transport costs. Using high volume bulk insulation puts pressure on these expenses.

Middleburg

Calvinia

Port St Johns Cradock

Saldnha Bay

East london

Uitenhage Worcester

Cape Town

Stellenbosch

George

Port Elizabeth

Mossel Bay

When comparing traditional roof membrane application, RadenShield™Double-Sided radiant barrier achieves the required R-Value thermal resistance using less bulk insulation volume. Traditional membrane used with 135mm insulation yields a total R-Value of 3.87m²K/W. RadenShield™Double-sided radiant barrier with 75mm insulation yields a total R-Value of 3.96m²K/W. Since less insulation is required, the project costs are reduced while still achieving the provisions based on the six climatic zones, shown on the map and table.

REQUIREMENTS FOR EACH CLIMATE ZONE WITH SAVINGS Climate zones

1

2

3

4

5

6

Cold interior

Template interior

Hot interior

Temperate coastal

Sub-tropical coastal

Arid interior

Minimum required Total R-Value (m²K/W) * for roof solar absorption of more than 0.55

3.7

3.2

2.7

3.7

2.7

3.5

Direction of heat flow

Up

Up

Down & up

Up

Down

Up

Total R-Value (high volume 100-135mm) with traditional membrane

3.87

3.37

2.99

3.87

2.99

3.87

Total R-Value (low volumne bulk fibre 50-75mm) with Radenshield™ Double-sided or Single-sided

3.96

3.37

2.74

3.96

2.74

3.96

Estimated Cost Saving

25%

15%

33%

25%

33%

25%

Climatic conditions

Total R-Values are based on the sum of all components of the building system including indoor and outdoor air films, building materials used in the system and air spaces. Assuming a 200m² home with roof pitch of 26 degrees – Ceiling: 200m² / Roof: 231m². Roof space: 0.49. Savings may vary based per current market values and are not guaranteed.

Radenshield™ Double-sided benefits Reflects 97% radiant heat Use less bulk insulation volume (135mm compared to 75mm) Material cost-saving of 25% Performance of R-Value 3.96m²K/W (in conjunction with 75mm bulk fibre) Thermal Conductivity – K-Value = 0.0630 W/mK

www.coverland.co.za | info.sa@monier.com Enquiry reference: SAR SANS 204

1 2 3 4 5

TM

DOUBLE-SIDED

with greater thermal resistance R-VALUE

RESIDENTIAL APPLICATION

Pure Aluminium Bonding Layer Non-Woven Carrier Bonding Layer Pure Aluminium

Spunsulation 5 Light Roofing Radiant Barrier

1.59(m2K)/W

4 5 6

Umtata

Sutherland

3

Tested and approved fit for purpose for use as a roof radiant barrier when used as specified in

CERTIFICATE 2009/369

COMMERCIAL APPLICATION

ROOFS THAT LAST

AWA R DS

“It is with great pride that Saint-Gobain Gyproc South Africa returns from the global awards with a South African project as one of the winners. This is testimony to the fact that South Africa is able to compete on a world stage when it comes to the best quality products coupled with a high level of skilled workmanship to produce a world-class masterpiece in construction, such as Cradlestone Mall. Our congratulations to Abbeycon (Pty) Ltd. on their achievement and for being ranked amongst the best drywall and plastering contractors in the world,� says Evan Lockhart-Barker, General Manager Marketing: Saint-Gobain Gyproc SA.

THE SAINT-GOBAIN GYPSUM INTERNATIONAL TROPHY This is a unique gypsum industry event and one of the largest international competitions of its kind.

Established in 1998 to recognize and reward craftsmanship of drywall and plastering contractors, the trophy aims to promote excellence and innovation in the use of sustainable and lightweight plasterboard systems and plasters.

The International Trophy campaign is organized by Saint-Gobain subsidiaries over a two year period, starting with regional and national events, and culminating in an international competition. This year, the International event was held in Berlin. 87 projects were entered and judged in six categories: plasterboard, residential, commercial, segment solutions, and plaster.

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SEPTEMBER 2014

COV E R S TO RY

Insultrak™ The new roof insulation spacer for over-purlin roof applications

I

nsultrak™ was borne out of extensive research and development initially conducted due to the problem presented by thicker faced fibre roof insulation materials being specified in over-purlin roof applications.

Since the inception of the SANS 10400-XA standard for Energy Usage in Buildings, there has been a marked increase in the use of thicker fibre blanket materials to attain the required thermal values for the building’s design. This, in turn, impacted on the effective fixing of the roof sheet for both secret-fix and standard roof sheeting systems in conjunction with the thicker insulation material.

• Ultra lightweight – adds no mass to the structure

The second problem that needed to be overcome during the R&D process was to find a material that would provide the required fire performance when used in these applications.

Following testing done to SANS 428 (fire performance classification of thermal insulated building envelope systems), a material was found that met these requirements.

• High compressive strength – 160-310kPa depending on thickness

The third requirement of importance was that the material used also needed to consist of an effective insulation material.

This would negate thermal bridging that would occur with many other raw materials and would enhance the total thermal value of the installed system.

The installation of Insultrak™ in conjunction with the fixing of the roof sheet is extremely simple. The Insultrak™ spacers are simply laid over the insulation on top of the purlin before fixing of the roof sheet, or clip system for secret-fix roof sheeting.

The final requirement, and by no means less important, was that the Insultrak™ spacer would improve the overall thermal value of the insulation material once installed by providing the maximum return loft of the fibre blanket. It was also found that the aesthetics of the faced fibre were not affected by the addition of the Insultrak™ spacer.

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Insultrak™ is manufactured from a lightweight, high-density closed-cell rigid foam in standard dimensions as required for the relevant thickness of insulation, and has the following value-added benefits:

• Excellent thermal value – Thermal Conductivity (K-Value) 0.024 W/m°C • 100% closed-cell structure – impervious to moisture or water absorption • High density – 32-36kg/m³

• Fire tested and approved for use in the required application • Can be combined with other approved roof insulation materials to improve thermals

The roof is then fixed down in the standard method applied for the relevant roof sheet with the addition of longer fixing screws to accommodate the packer. Insultrak™ is supplied in standard 3m lengths, which are 75mm wide and available in the following thicknesses: 25mm, 40mm and 75mm. Alternative thicknesses may be produced upon request.

SEPTEMBER 2014

COV E R S TO RY

Insultrak TM Spacer

Insultrak TM Spacer

100mm Faced Fibre Insulation Full 100mm thickness achieved

Roof sheet Insultrak TM Purlin

Insultrak TM Spacer

Insultrak™ was designed, developed and patented by D&D Roof Insulations. The company has been one of the leading innovators and suppliers of most commercially available roof insulation products in South Africa for the past 15 years. Following previous product successes, such as the development of Starlite®, which was the first faced fibre roof insulation material in South Africa to achieve an A1 fire rating, the development of a solution such as Insultrak™ was a natural progression.

FOR MORE INFORMATION, CONTACT: (t) 012 800 3606 (e) info@insultrak.co.za (w) www.insultrak.co.za / www.roofinsulation.co.za

SEPTEMBER 2014

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I N D U S TRY I N S I G HT

Your erected roof structure: Will your bank or insurance company assume the risk?

Part 2: The erection must be according to SANS 10243 and the ITC-SA's Roof Erectors Handbook, Volumes 1 & 2

By Lyndsay Cotton, General Manager of LCP Roofing and Chairman of the ITC-SA.

I N D U S TRY I N S I G HT

I N D U S TRY I N S I G HT

T

he manufacture and erection of timber roof trusses in South Africa is governed by SANS 10243 and if the fabricator is one of the select few that are permitted to apply the SANS 1900 mark of quality, the consumer can rest assured that the quality assurance of the manufactured product is of the highest National Standard. But what are the consequences if the roof structure has not been erected in a professional manner?

There are only four ITC-SA and SAQA (South African Qualifications Authority) accredited system software suppliers in South Africa that are permitted to supply software and nail plates for the manufacture of monoplaner timber trusses in South Africa. Site-manufactured trusses, nail plates or bolted and nailed trusses with hips and valleys are not permitted unless the contractor can prove that each and every truss and connection detail has been designed and inspected by an engineer who is generally recognised as having the necessary experience and training to undertake rational designs in the field of roofs and roofing.

6 POINTS TO CONSIDER WHEN APPOINTING YOUR ERECTOR ACCREDITATION: All ITC-SA fabricator quotations in South Africa are required to have the ‘Please use a qualified ITCSA roof erector’ logo on their quotes. Similarly, all site documentation is also required to bear this imprinted logo.

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Check the ITC-SA website to confirm that the erector is not only a current member of the ITC-SA, but more importantly, that the erector is certified competent to erect a roof structure which falls within his category of competence. There are four categories of roof structures and these can be obtained from the ITC-SA website at www.itc-sa.org.

SITE DOCUMENTATION: The provision of site documentation is a function of the fabricator and an erector will not be able to erect a roof structure according to the design intent if the documentation is not according to the minimum requirements of the ITC-SA. The erector should therefore be in possession of a truss layout drawing inclusive of all connection and bracing details.

Additionally, all girders, design codes and loadings employed are to be noted. Client, fabricator and site details must also be clearly indicated on the site drawings.

ERECTION TECHNIQUES AND HANDLING: The Roof Erectors Handbook Volumes 1 & 2 as issued by the ITC-SA for the installation and bracing of pre-fabricated timber roof trusses is the sole authoritive publication for erectors in South Africa and covers all aspects of erection techniques. The details are all ‘deemed to satisfy’ and they may be superseded by an alternative detail issued by a competent, experienced and registered timber engineer.

The erector’s possession of these books on site should not be negotiable. Some software systems issue similar documents, but in essence their content is the same.

SEPTEMBER 2014

I N D U S TRY I N S I G HT Trusses should always be carried in an upright position or supported at all important nodes if carried horizontally or when hoisting into position. On large roof spans and bigger construction sites where buildings exceed two storeys or more, the uses of adequate cranage and spreader bars should be specified. Alternately, the main contractor should provide for hoisting facilities.

It is all too often left to the erector to allow for hoisting and this is not normally provided for in the erection quotation. The erector will then attempt to pull or push the trusses up the side of the building which will not only weaken the trusses, but also create a health and safety risk.

The roof structure should be completely braced and torsional straps fitted before the loading of the roof structure with the roof covering. Torsional straps should be fully nailed with at least 15 nails on each side of the connection.

Loading should equally not be placed on the structure before fitting, as uneven loading will create unevenly distributed loads and could cause the structure to buckle or collapse. Although of a lesser importance than bracing, wallplates should be installed according to the minimum specifications as noted on the following table:

WALL PLATE SIZES

KNOWLEDGE OF BRACING AND HOLDING-DOWN REQUIREMENTS: Bracing of any framed structure is vital to ensure stability of all the components and the same unequivocally applies to timber roof structures.

The following bracing types are normally utilised and the Roof Erectors Handbook should be consulted to determine if it applies to the structure in question: • Stability bracing (also known as wind- or diagonal bracing) • Web stiffeners (also known as ‘T’ bracing) • Web runners • Bottom chord runners • Top chord stiffeners • Bracing frames • Shelves (used in conjunction with stability bracing)

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1

2

Truss Span S m

Cross-section of plate mm

S ≤ 10

38 x 76

10 < S ≤ 15

38 x 114

15 < S ≤ 20

38 x 152

Trusses should under no circumstances be modified on site unless the modification has been confirmed by the designer/ engineer and a written instruction issued. Part 4 of the Roof Erectors Handbook details the most common site remedials.

SEPTEMBER 2014

I N D U S TRY I N S I G HT

Part 8 of the regulation makes it quite clear that a competent person in respect of inspections (for roof structures) certifies that the structure has been erected according to the design intent. This does not necessarily mean that the roof structure has been designed correctly.

The competent person will, however, be unable to issue the Regulation A19 completion certificate if he does not have access to complete site documentation as mentioned earlier.

Bracing is all too often misunderstood and inadequately specified by the designer. It is thus up to the roof inspector as a last point of inspection to confirm compliance.

THE CONSEQUENCES OF NONCOMPLIANCE:

Nailing is just as important as bolting, and all bracing must be nailed according to the specifications. Most connection details allow for two or more nails per connection and this requirement is to be specifically checked for each and every bracing detail. Unless otherwise specified, nailing of web stiffeners and girders is stagger-nailed at 150mm centres.

Spacings of greater than 150mm in these instances are inadequate and are not permitted.

The erector should ensure that the trusses are fixed to the supporting structures in the correct and prescribed manner and, although the provision of the holding down detail is the responsibility of the main contractor, the erector will not be excused from a certain level of liability if he does not bring incorrect practices to the attention of the contractor.

The specifier or architectural designer is to take specific note of the holding-down requirements, as these differ between lightweight and heavy roof coverings.

Simply said, the consequences of non-compliance with the national standards may eventually result in a roof failure with potentially disastrous results and repair costs far exceeding the original roof costs by a significant margin.

BENEFITS: The benefits of insisting on the aforementioned standards will ensure that the building owner has an expertly erected roof structure and the owner will furthermore rest assured that the risk of failure due to poor erection and inspection practices is mostly eliminated.

Naturally, the design or fabrication should be strictly according to the output of the system software and the guidelines of SANS 10243 and SANS 1900.

In part one of this article, published in the July 2014 issue of the SA Roofing magazine, we investigated the dangers of poor design and fabrication techniques. Even a perfectly manufactured truss system will fail within the first 7 to 10 years if incorrectly erected and poorly braced.

TOOLS: An ITC-SA accredited and professional erector will use good quality tools and the measurement of his work can be assessed by inspecting his tools before the job commences.

Hand saws should be sharp at all times and power saw blades will not be blunt or burnt along the cutting edges. A competent erector will always use a spirit level to plumb and level trusses, and have a sliding bevel to ensure that all angled cuts are consistent. Hangers will always be marked on the ground and squared off by using a decent carpenter square. Chalk lines are used to mark spacings for brandering and purlins. The erector will always have different length tape measures to cater for varying spans and runs.

FOR MORE INFORMATION PLEASE DO NOT HESITATE TO CONTACT THE WRITER FOR CLARIFICATION AND EXPERT ADVICE: (c) 082 441 5026 | 0861 LCPROOF (e) lyndsay@lcproofing.co.za (w) www.lcproofing.co.za

INSPECTIONS: A suggested worksheet for roof inspections can be found in either the ITC-SA's Roof Erectors Handbook Vol. 2 â&#x20AC;&#x201C; Part 3, or SANS 10243 â&#x20AC;&#x201C; Annex F. This would be a good starting point to ensure that all pertinent items are covered.

Regulation A19 of SANS 10400-A (Application of the National Building Regulations) deals with the appointment of a person responsible for the design, inspection or assessment of a structural component.

26

SEPTEMBER 2014

ZAP FASTENING SYSTEMS OFFERS YOU: The widest range Guaranteed quality and performance Best value for money Nationwide distribution

ZAP FASTENING SYSTEMS ARE SUITABLE FOR ALL ENVIRONMENTS Z2 ELECTROPLATED SCREWS

Z3 DUPLEX COATED SCREWS

Made to SANS1273 Class 2 specifications for use in mild rural and urban areas. Compatible with Z275 sheeting

Made to SANS1273 Class 3 specifications. For use in moderate marine and industrial environments.

Compatible with Zinc Aluminium coated sheeting

Z4 DUPLEX COATED SCREWS

Z5 BI-METAL STAINLESS STEEL SCREWS

Made to SANS1273 Class 4 specifications. For use in severe marine and industrial environments.

Compatible with painted Zinc and painted Zinc Aluminium coated sheeting

Made for ISO9223 Class 5 environments. For use in very severe marine and industrial environments.

Compatible with stainless steel and aluminium sheeting

ZAP FASTENING SYSTEMS HAVE A VARIETY OF HEAD STYLES AND DRILL POINTS FOR ALL APPLICATIONS

ZAP FASTENING SYSTEMS RANGE FROM 13MM TO 180MM IN LENGTH

Zap fastening systems are distributed nationwide by KARE INDUSTRIAL SUPPLIERS Johannesburg (011) 334 0922

Durban (031) 705 5610

Cape Town (021) 592 4577

Pretoria (012) 332 4073

Port Elizabeth (041) 451 1447

FA S TE N I N G S YS TE M S

Safety overhead Roofing fasteners play a crucial role in the overall performance of a roofing system.

Unfortunately, the importance of fasteners is often overlooked and it is only after they fail and problems occur that proper attention is given to fastener selection.

By Reitze Hylkema, Managing Director, Kare Industrial Suppliers

S

ince the publication of the revised standard relating to roofing fasteners, SANS 1273, in November 2009, a much wider range of corrosion-resistant coatings on roofing fasteners has been on offer to the roofing and cladding market. Regrettably, a lot of these fasteners do not conform to the SANS 1273 coating requirements, despite some rather exaggerated performance claims by the importers.

By following a few simple guidelines it is easy to select the correct fasteners and corrosion-resistant coatings which will ensure that the fasteners will not become the weak link in the roofing system. While more outdated types of fasteners are still used in the roofing market, and are still listed in SANS 1273, this article will concentrate only on the more popular self-drilling-type fasteners.

Factors that need to be taken into consideration when selecting suitable roofing fasteners:

FASTENER SELECTION

The drill point diameter is in correlation with the thread diameter and influences the pull-out values obtained in different steel thicknesses.

When fixing fibreglass, polycarbonate and fibre cement sheeting, an oversized hole in the sheeting is required in order to allow for expansion and contraction of the sheeting. By using a winged self-drilling screw, the reaming process can be done while fixing the fastener.

FASTENER HEAD SELECTION When IBR and corrugated profiles are fixed, the fasteners are fixed through the sheeting into the purlins. This is referred to as a pierced-fix roofing system. Either hexagon head, hex washer head or hex flange head screws are used for pierced-fix applications. Hexagon head and hex washer head screws are used in combination with bonded washers, while hex flange head screws are normally assembled with a rubber seal not requiring an additional bonded washer.

FASTENER POINT SELECTION The following information is required to select the correct drill point: 1. Will the screw be drilling into timber or into steel? a. If fixed into timber, then a screw with a Type 17 point should be used:

Hex washer head

Hex flange head

No. 1 point: Stitching of thin gauge material (i.e. flashing and sheeting; end laps and side laps) and fixing into thin gauge metal battens.

With concealed-fix roofing systems a clip, bracket or halter is fastened onto the purlin and the sheeting is clipped, hooked or seamed onto the clip. These systems allow the sheeting to expand and contract without movement restriction from pierced fasteners. As a result, much longer continuous spans can be rolled.

Most of the concealed-fix roofing system requires a wafer head fastener that fits flush in Wafer head the recess of the clip.

No. 2 point: 2.5mm drilling capacity in cold rolled steel.

FASTENER LENGTH CALCULATION

2. If fixed into steel, then a screw with a drill point with the correct drilling capacity should be used:

No. 3 point: 4.5mm drilling capacity.

This is by far the most popular drill point and commonly used for fixing sheeting to 2.5mm cold rolled lip channel.

No. 4 point: 12.5mm drilling capacity.

This drill point is used on hot rolled steel sections.

30

Hexagon head

To calculate the correct fastener length for pierced fixing through the crest of the sheeting, the following numbers must be added: 1. The profile height of the sheeting.

2. The thickness of washers and seals.

3. The compressed thickness of insulation material between the sheeting and the purlin.

4. The thickness of the purlin in case of steel purlins.

5. The length of the drill point and the first three threads above the drill point (in case of steel purlins).

6. 35mm penetration into the timber in case of timber purlins.

SEPTEMBER 2014

Note: SANS 1273–2009 lists sherardizing and hot dip galvanizing as suitable corrosion-resistant coatings for fasteners other than self-drilling screws.

When fixing through the valley (pan) of the sheeting, the same calculation applies, but the profile height is omitted.

In order to prove compliance with the corrosion-resistant coating requirements of the standard, at least one of three testing methods has to be conducted. The three options are: 1. Accelerated laboratory testing 2. ‘Deemed to comply’ based on the porosity rating, the coating thickness, and the coating composition.

3. Real world testing

When fixing concealed fix roofing systems, the correct fastener length is calculated as follows: 1. The compressed thickness of insulation material between the sheeting and the purlin plus the height of any packers between the insulation and the purlin.

2. In the case of fixing into steel purlins, add the thickness of the purlin, the length of the drill point and the first three threads above the drill point.

3. In the case of fixing into timber purlins add 35mm for penetration into the timber.

CORROSION CONSIDERATIONS The corrosion resistance requirements of roofing fasteners is described in SANS 1273–2009, which draws on the information published in the Australian Standard AS3566.2-2002. In the standard, corrosion-resistant coating types, thicknesses and compositions are specified and linked to environmental categories. The environmental categories are based on ISO9223, which lists the following corrosion resistance classes: CORROSION RESISTANCE CLASS

ATMOSPHERE OF INTENDED USE

1

General use in internal application

2

Internal applications with significant condensation levels External applications: Inland rural & mild urban

3

External use in moderate industrial or marine environments

4

External use in severe industrial or marine environments

5

External use in very severe industrial or marine environments

Only Class 2 and higher classes apply to external roofing and the specification of the coating for self-drilling screws in these categories is as follows: CORROSION RESISTANCE CLASS

ACCELERATED LABORATORY TESTING Accelerated laboratory testing is conducted according to AS3566.2-2002 and requires salt fog tests and sulphur dioxide tests to be performed on metallic-coated self-drilling screws.

The fasteners that are to be tested are first driven into a 1.5mm-thick galvanized steel plate and removed, or, in the case of screws for timber, the screws are driven a minimum of 30mm into untreated pine and then removed. Only after this procedure can the screws be tested.

The fasteners shall pass the following tests without showing signs of red rust on more than 5% of the head and shank of the self-drilling screw.

MINIMUM HOURS IN NEUTRAL SALT FOG TEST

MINIMUM HOURS IN SFW 2.05 SULPHUR DIOXIDE TEST

Class 2 fasteners 240 Hours

5 Cycles

Class 3 fasteners 1000 Hours

15 Cycles

It is important to note that accelerated laboratory testing is not listed in the standard as a method to test Class 4 coatings.

By following a few simple guidelines it is easy to select the correct fasteners and corrosion-resistant coatings which will ensure that the fasteners will not become the weak link in the roofing system.

MINIMUM COATING TYPE POROSITY RATING

COATING COMPOSITION MINIMUM LOCAL METALLIC (BY MASS) COATING THICKNESS (μm)

2

-

Electroplated Zinc

98% Zinc

12

3

-

Electroplated Zinc

98% Zinc

30

3

8

Mechanically plated Zinc

98% Zinc

40

3

8

Mechanically plated Zinc/Tin 20-23% Tin. Balance Zinc

25

4

8

Mechanically plated Zinc/Tin 20-23% Tin. Balance Zinc

45

SEPTEMBER 2014

FA S TE N I N G S YS TE M S

The length obtained is the recommended length of the fastener. If this is not a standard length, then the next longer standard length is recommended.

31

FA S TE N I N G S YS TE M S

DEEMED TO COMPLY If the coating thickness, the coating composition, and the coating porosity conform to the specifications of the table in the standard, the fasteners are deemed to comply with the standard.

This method of testing can be used for Class 2, Class 3 and Class 4 fasteners. In order to achieve compliance this way, the following tests are required: The coating thickness must be measured on the flange of the head of the fastener or on the side of the hexagon head. On wafer head screws the thickness must be measured on top of the head. Three separate readings must be obtained and all three must meet the standard requirement.

Above: Covered (unwashed) real-world test panel in marine environment On a real-world test site, Zinc coupons are fixed on the same exposure rack as the fasteners and sheeting. The Zinc loss of the coupons is monitored at regular intervals.

Once the coupons have lost 21 microns of Zinc in the case of testing Class 3 screws and 42 microns of Zinc in the case of Class 4 screws, 95 out of 100 screws that are tested must show no signs of red rust on the head and/or shank of the fastener.

The coating composition of Zinc/Tin coatings must be analyzed and the tin content must make up between 20 and 23% of the coating with the balance being Zinc.

The porosity of mechanically plated screws must be inspected by placing a cross section of the coating under a microscope with a magnification of 500x and comparing the image with the images listed in the standard as shown above. A rating of 8 is required to comply with the standard.

REAL-WORLD TESTING Real-world testing is the most reliable and realistic method of testing, as it combines the fasteners, the washers, the roof sheeting and the trusses in contact in an aggressive environment which can combine varying temperatures and conditions.

Above:The top row shows the zinc coupons used as the corrosion rate indicator.

MATERIAL COMPATIBILITY When selecting fasteners, it is important to ensure that both the fastener and the corrosion-resistant coating are compatible with the roof sheeting. If not, the result will be galvanic corrosion. In light of this, it is advisable to carefully read the specifications of the sheeting manufacturers. Often the warranty on sheeting material is subject to the correct fasteners being used.

As a general guideline, the following combinations of fasteners and roof sheeting are recommended: If using dissimilar metals together is unavoidable, it is advisable to use a non-conductive sleeve around the fastener to prevent contact between the fastener and the sheeting.

32

SEPTEMBER 2014

ZINC COATED STEEL

ZINC ALUMINIUM COATED STEEL

PAINTED ZINC COATED STEEL

PAINTED ZINC ALUMINIUM COATED STEEL

Class 2 Zinc electroplated

X

Class 3 Mechanically plated

X

X

X

X

Class 4 Mechanically plated

X

X

X

X

ALUMINIUM & PAINTED ALUMINIUM

Class 5 Stainless steel

STAINLESS STEEL & PAINTED STAINLESS STEEL

X X

X

This is essential, especially in highly corrosive environments. Usually, this will necessitate the pre-drilling of an oversized hole in the sheeting to accommodate the sleeve.

GENERAL CONSIDERATIONS

Above: A 316 Stainless steel fastener in contact with a painted Zinc/Aluminiumcoated steel roof sheet resulting in corrosion.

In addition to the abovementioned factors that influence fastener selection, the following issues should also be considered: In pierced-fix roofing applications, it is advisable to fix the screws through the crest of the profile and not through the valley (pan) of the sheeting.

THIS IS FOR THE FOLLOWING REASONS: â&#x20AC;˘ Valley fixing does not allow for expansion and contraction of the roof sheeting and will result in the hole around the fastener becoming elongated leading to possible leaks. â&#x20AC;˘ Rain runs off the crest of the sheeting and into the valley. Fastener heads will form an obstruction in the valley behind which debris will accumulate. This will lead to premature corrosion of the sheeting behind the fasteners.

It is not advisable to use pierced-fix roofing systems on spans longer than 18m, as expansion and contraction will cause fasteners to work loose over time and strip the holes in the purlins. This span length is reduced when fixing into thin gauge metal battens. For longer spans, concealed-fix roofing systems are recommended.

All swarf and metal filings should be removed from the roof sheeting after the roofing fasteners have been installed, as these filings will cause corrosion and damage the roof sheeting very quickly.

If bonded washers are used, it is important that the corrosion resistance of the washers matches that of the fasteners and the roof sheeting. Non-conductive rubber should be used on washers in order to eliminate the problem of pit corrosion, especially on Zinc/Aluminium-coated sheeting and Aluminium sheeting.

Selecting the correct fastener type and appropriate coating before the start of the project will prevent costly repairs and eliminate problems caused by premature corrosion in the long run. If there is any doubt about which fasteners and/or coatings to use, it is safer to consult with the roll former or specialist fastener supplier.

SEPTEMBER 2014

ISOVER’s Factorylite Insulation Factorylite is a leading Glasswool roof Insulation faced on one side with either a reinforced foil or white metalized foil. It is specially developed for metal buildings and has two main attributes that are critical when choosing insulation. Firstly stabilizing the indoor comfort levels providing efficient thermal and acoustic properties and secondly the assisting with the prevention of moisture collecting due to condensation which can lead to physical degradation.

Factorylite Features and Benefits Energy Efficiency - Meets the requirements of SANS 10400 XA by reducing heat loss/gain due to the inherent thermal insulation properties and is suitable for high humidity applications.

Acoustic Properties - Offers exceptional acoustic properties & enhances indoor environmental quality by absorption of noise.

Fire Properties - Factorylite is a non combustible material tested to SANS 10177 Part 5 and SANS 428:2012, achieves a Class 1 fire index rating when tested to SANS 10177 Part 3.

It also meets the international norms and standards tested to EN 13823, EN 13501-1 and ASTM E-84 Environmental Sustainability - Glasswool is made from a combination of naturally occurring silica, fluxing agents and up to 80% recycled glass. Glasswool has a Zero Ozone Depleting Potential (ODP) and no CFC’s or HCFC’s are produced in the production process.

Lamination The lamination process of applying adhesives and a facing to the Glasswool insulation blanket is a critical part of the product’s designed performance. It can greatly affect the thickness recovery of the insulation and the fire properties of the material due to the performance of the facing and amount/ type of adhesive applied. ISOVER’s lamination process is monitored under stringent conditions in accordance to ISO 9001.

Condensation Condensation should be controlled in metal buildings, as condensed water droplets on the metal can corrode the integrity of the structure. Using aluminum foil on its own as a vapor-retarder does not control condensation. Factorylite insulation is of utmost importance as its thermal performance assists in the dewpoint not being reached.

Accreditation

Membership

Tel: 0860 ISOVER (476837) Fax: 086 673 1088 www.isover.co.za Download the isover SA app

• Metal Buildings • Shopping Centres • Commercial Buildings • Warehouses • Schools • Hospitals

AL

R E S I S TA N C E

TH

ER

M

Factorylite insulation meets the requirements VA L

UE

Tel: 0860 ISOVER (476837) Fax: 086 673 1088 www.isover.co.za Download the isover SA app

NEWS

There’s a new kid on the AAAMSA block SANEDI and AAAMSA, together with the South African Department of Energy and the United States Department of Energy’s Global Superior Energy Performance Partnership (GSEP) initiative, formed the South African Cool Surfaces Association (SACSA) on 6 February 2014 at the CMA Conference Centre in Midrand.

D

r. Wolsey Barnard, the Deputy Director General from the Department of Energy, representing Government and other industry leaders from the private and public sectors, participated in the formation of this new, exciting, ground-breaking association that aims to put cool surface technology on the South African map.

The purpose of the formation of the South African Cool Surfaces Association is to establish a non-profit organization to: • Develop accurate and credible methods for evaluating and labelling the solar reflectance and thermal emittance (radiative properties) of roofing (surfaces) products; • To disseminate the information to all interested parties; and • To create employment opportunities through training.

At the inaugural meeting, stakeholders discussed how available innovative technologies, materials and interventions, as well as projects that have been successfully implemented elsewhere, can be implemented in South Africa in order to improve thermal comfort, energy efficiency and sustainability of buildings in South Africa.

Dr. Wolsey Barnard

AAAMSA was officially appointed as the administrator of the new association. As with any new association, the ground work is being done to establish the correct standards and performance requirements in collaboration with the SABS to regulate the industry, as it is a new phenomenon in South Africa with which architects are not familiar.

The two basic characteristics that determine the ‘coolness’ of a roof are solar reflectance (SR) and thermal emittance (TE).

Both properties are rated on a scale from 0 to 1, where 1 is the most reflective or emissive. Specialised paints are applied to external surfaces to lower rooftop and building temperatures, which results in less heat transfer, resulting in the reduction of energy consumption. Naturally, rating and labelling are of utmost important to protect the professionals and consumers of erroneous claims.

Mr. Kadri Nassiep, CEO of SANEDI and Mr. Hans Schefferlie, Executive Director of the AAAMSA Group.

For more information contact Des Schnetler at AAAMSA on 011 805 5002.

36

SEPTEMBER 2014

Cnr Berkley and Bax Roads, Maitland 7405

New extension to 28 Hudson Street, de Waterkant, in Zincalume Snaplok, Image and architecture courtesy of Leon Saven Design

PROJ EC T F E AT U R E

On the face of it In recent years, architects and designers have embraced using metal roof sheeting when designing modern, striking buildings, not only for aesthetic value, but to add to the buildingsâ&#x20AC;&#x2122; green credentials and to save on the bottom line.

Images: David Rogers

PROJ EC T F E AT U R E

PROJ EC T F E AT U R E

F

40

or many years, profiled metal sheeting has been specified extensively for all manner of building types, not only as a roof covering, but also for external wall cladding.

Traditionally used for agricultural and industrial buildings, steel roof sheeting is now a very popular choice among building professionals and is an integral component of residential and commercial building design.

MOTORPORT BAYSIDE

Steel roofs provide a flexible, cost-effective and durable solution to any building. When combined with insulating materials, like Lambdaboard, Thermocoustex and Romatherm, a durable, weatherproof and comfortable working or living environment can easily be achieved.

This project was not only about creating an attractive modern faรงade from a durable, modern material, but also about complying with national building regulations for energy efficiency. The project took approximately three months to complete.

Youngman Roofing, a leading supplier of steel roofing and insulation, has recently supplied the most appropriate and cost-effective solution to two exciting projects, including the roof and faรงade of the Bayside Motorport car dealership in Table View, and the new 360 Business Park in Paarden Eiland, Cape Town.

PROJECT DATA:

A client whose showroom is almost as important as the stock they sell, Motorport Bayside car dealership required the replacement of the existing roof and faรงade. They also required the complete gutting of the interior and remedial steel work; all in all, a complete overhaul of their existing showroom.

MOTORPORT BAYSIDE, TABLE VIEW: ROOF SHEETING PROFILE: Diamondek Concealed Fix CLADDING: IBR MATERIAL: Clean Colorbond Ultra Steel from BlueScope Steel INSULATION: Sisalation 405 and Lambdaboard FASTENERS: Corroshield Class 4 fasteners

SEPTEMBER 2014

PROJ EC T F E AT U R E

41

SEPTEMBER 2014

PROJ EC T F E AT U R E 360 BUSINESS PARK, PAARDEN EILAND

PROJECT DATA:

An innovative concept embracing the modern-day work environment, 360 Business Park in Paarden Eiland offers different types of temporary of office spaces, catering to a great variety of workplace needs.

ROOF SHEETING PROFILE: Diamondek Concealed Fix CLADDING: IBR MATERIAL: Clean Colorbond Steel by BlueScope Steel INSULATION: Sisalation 405 and Romatherm FASTENERS: Corroshield Class 3 fasteners

360 BUSINESS PARK, PAARDEN EILAND:

The project called for a complete redo of both the roofing and cladding, and to add a striking faรงade to a building that houses a business of the future. The prominently positioned curved faรงade offered up a challenge, which was met by using cranked sheeting.

42

SEPTEMBER 2014

PROJ EC T F E AT U R E Both clients are exceedingly happy with the outcome of their projects, which stand as showcases for the remarkable possibilities that come with using steel in commercial projects. On the outside, these buildings represent what they house, and do so not only in style, but with great purpose.

For more information, visit www.youngman.co.za.

SEPTEMBER 2014

43

E V E NT S

Interbuild Africa 2014 prepares to launch Interbuild Africa 2014 is less than two months away from opening its doors. Showcasing more than 400 exhibitor stands and a wide variety of new show features, the show organisers are confident that they will exceed their 2012 visitor attendance record.

“We welcomed more than 9 000 visitors at our last event in 2012,” says Gary Corin, Managing Director of Specialised Exhibitions Montgomery. “With the support of some of the leading industry associations and the introduction of some innovative new features for 2014, we aim to improve on these figures and introduce Interbuild Africa to a much wider audience,” he says.

Interbuild Africa, together with its co-located events – Glass Expo Africa, Plumbdrain Africa, EcoAfribuild, Woodpro Africa and Hardex Africa – constitutes the biggest building and construction expo in Africa. This year’s event is taking place from 20-23 August at the Johannesburg Expo Centre in Nasrec.

Interbuild Africa 2014 has been endorsed by some the leading industry bodies and associations in the building and construction sector today, all of which will play a key role in facilitating some of this year’s top features. The event organisers are pleased to welcome the support of the National Home Builders Registration Council, the South African Bureau of Standards, The Concrete Institute, the Institute of Plumbing South Africa, the South African Institute of Architects, and the Association of South African Quantity Surveyors. The Master Builders Association of South Africa will host its annual board meeting at Interbuild Africa 2014, while the show’s supporting industry associations host their annual conferences at this year’s event.

The conferences will offer delegates the opportunity to gain insight from top industry professionals while earning Continuous Professional Development (CPD) Points. These associations include: The South African Light Steel Frame Building Association, the Association of Quantity Surveyors South Africa, South African Glass Institute, South African Glass and Glazing Association, as well as the Association of Architectural Aluminium Manufacturers of South Africa.

44

Interbuild Africa 2014, is also pleased to announce that it will award three bursaries to the value of R10 000 each, to three winning students, through the South African Institute of Architect’s OpenArchitecture Initiative.

Interbuild Africa 2014 will also include a free-to-attend seminar programme, aimed at bringing attendees up to speed with the latest trends impacting on the building and construction sector, including: changes to the new BEE Codes, changing occupational health and safety regulations, and green building developments.

“Interbuild Africa provides exhibitors with an unrivalled platform to meet new and existing customers, launch new products and build up an enviable list of new sales leads,” says Corin. “For visitors, the show provides an extensive showcase of the latest innovations, products and services, while hosting a number of highly informative seminars, conferences and unparalleled networking opportunities. We look forward to welcoming you to Interbuild Africa 2014,” he concluded.

Builder’s Warehouse, one of the show’s exhibitors has also come on board as a key sponsor to support visitor attendance through the sponsorship of well over R30 000 in prizes.

Interbuild Africa 2014 will take place from 20-23 August 2014 at the Johannesburg Expo Centre in Nasrec. For further information or to book your stand, visit www.interbuild.co.za.

SEPTEMBER 2014

BRONX INTERNATIONAL The Leading Supplier of Quality Process Lines in Africa Australian designed, European build Colour Coating Line

Kenya

2012

Colour Coating Line

Nigeria

2012

Galvanising & Zinc / Aluminium Coating Line

Kenya

2008

Colour Coating Line Upgrade

Nigeria

2005

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Nigeria

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Nigeria

2004

Galvanising Line Upgrade

Kenya

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Colour Coating Line

Nigeria

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High Speed Galvanising Line

Nigeria

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Colour Coating Line

Nigeria

1999

Galvanising Line

Kenya

BU I L

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Colour coating lines Galvanising lines Upgrades to existing lines Galvanising coating control equipment Pattern coating Paint & chemical coaters Tension levellers Process technology

O G PR CE S S

in

L IN

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2012

Quality Suppliers of:

SIN

C E 19 9

BRONX INTERNATIONAL

ES

Africa 9

email: sales@bronx.com.au

www.bronxintl.com

PRO D U C T PRO F I LE

Clever colour coating from Bronx International The colour coating of steel and aluminium has traditionally relied upon conventional large colour coating lines which need to produce high volumes to be economical. These bigger lines require large infrastructure and highly skilled operator and maintenance teams to run them.

O

ver the past few years, Bronx has developed a range of easy to operate â&#x20AC;&#x2DC;Warehouseâ&#x20AC;&#x2122; lines to enable smaller companies to break into the coil-coating industry and provide greater opportunities for their businesses.

These are cleverly designed, compact coil-coating lines that minimise the factory floor area and height required, which, in many cases, allows a line to fit within an existing warehousing area.

With lines starting at less than 60m long and fitting in less than 5m height, and requiring minimal foundations due to their flat floor design (a significant cost incurred with larger lines), more businesses are considering this solution.

Bronx has 13 references in Africa, including two Warehouse lines installed in 2012. Three further Warehouse lines are under construction and interest is growing as more companies look at the considerable benefits these lines provide.

These lines are designed in modular units, which reduce the installation and commissioning time. They can be reconfigured with options to meet the customerâ&#x20AC;&#x2122;s market needs: quickchange coaters, protective film applicators, embossers and pattern coating. For aluminium architectural products, lines are up to 1600mm wide.

Coating and curing systems can handle a range of products from polyester and polyvinylidene fluoride (PVDF) to plastisols. Thermal equipment includes heat recovery to ensure maximum operating efficiency, and cascade flows on cleaning equipment minimise water consumption.

46

Bronx pattern coating

SEPTEMBER 2014

Belpanel U Wrap Coater

Coating your own coil can also result in higher profit margins, because the difference between buying pre-painted coil and painting it yourself is kept by you. You also can provide shorter lead times and quick delivery; it can be ordered today and painted tomorrow. The ability to offer unique colours, patterns and embossed coil are some of the products you can bring to the market. In addition, you benefit from a reduction in coil inventory because you can stock a minimum quantity of coil.

This innovative system also enables you to charge a premium for customers ordering a minimum quantity, new colours or early delivery.

The Warehouse line package comes complete with technology transfer, operator training, laboratory equipment and special operating tools, ensuring that all customer requirements are covered.

FOR MORE INFORMATION, CONTACT: Jaco De Waal (c) 082 821 3713 (e) salesteam@bronx.com.au (w) www.bronxintl.com

Leather embossing

Reg No: CoR18.3 2013/068719/07

VAT No: 4930188372

Suitable for coastal areas 2000 Hour Salt-Spray Test Anti-Corrosion Screws

Manufactured in Taiwan DBN Branch: Contact: Summers | Tel/Fax: 031 - 765 1604 | Cell: 082 564 1463 | hengfusa@gmail.com JHB Branch: Contact: Tanny | Tel: 011 - 979 5026/7 | Cell: 082 782 6854 | P.O. Box 14353, Bredell, Kempton Park

www.hengfuscrews.co.za

PRO D U C T PRO F I LE

The AC drive system allows for maximum load-sharing between drives and minimises energy required from the supply. The inclusion of water processing and treatment means the line is not only cost-effective to operate, but meets the most stringent environmental conditions.

H OT D I P G A LVA N IZI N G

Hot Dip Galvanizing of Sheet Metal

Hot dip galvanized sheet is produced on continuous zinc coating lines from either cold rolled (thickness range 0.27 to 2.0mm) or hot rolled (thickness range 2.1 to 3.0mm) steel coil to the requirements of SANS 4998 and SANS 3575 or ASTM A653. Specification SABS 934 should no longer be referred to as it has been replaced by SANS 4998/ISO 4998 and SANS 3575/ISO 3575.

S

teel coils are welded end-on-end to form a continuous strip. After degreasing, the strip is pickled or oxidized. Oxides are then removed from the surfaces by reduction at 950°C. At the same time the strip is soft-annealed. The surfaces of the strip, now chemically clean, are moved through a protective gas atmosphere and directly down into the zinc bath. The strip is withdrawn from the bath vertically and passed through ‘air knives’. Controlled jets of air or steam are blown through the knives, wiping the zinc coating to the desired thickness.

The galvanizing process yields an even zinccoated sheet with a bright smooth metallic finish. The zinc coating can be supplied with a regular or flattened minimised spangle finish.

After cooling, straightening and treatment against wet storage stain, the strip is cut into suitably sized sheets or rolled into coils for delivery or subsequent painting and/or profiling (figure 1).

ZINC COATING SURFACE FINISH The following surface finishes may be ordered to suit specific end-use requirements:

REGULAR SPANGLE (ALSO KNOWN AS NORMAL SPANGLE) This is the unaltered, large, multifaceted crystal structure that occurs during normal solidification of a hot dip zinc coating on a steel sheet. Variations in the size and brightness of the spangles are possible, depending on the galvanizing process and conditions, but this has no effect on the quality and corrosion resistance of the coating. Regular spangle is supplied for a wide range of applications where overpainting for maintenance purposes can be undertaken at a later stage.

FLATTENED MINIMISED SPANGLE This is a zinc coating that is obtained by restricting the normal zinc crystal growth followed by the application of a skin pass process.

The zinc coating thus obtained has improved formability and the zinc surface serves as an excellent base for pre-painting, post-painting and powder coating applications.

48

Figure 1. Schematic diagram showing the continuous hot dip galvanizing process for the coating of sheet.

This finish is recommended for applications where a high gloss paint finish is required. It is available for zinc coatings of mass up to Z275, and a maximum steel thickness of 1.20mm if passivation is required, or a maximum steel thickness of 1.60mm if passivation is not required. Zinc coatings of different thicknesses in accordance with SANS 4998/ISO 4998 or SANS 3575/ISO 3575 may be ordered to suit specific end-use requirements. Certain coating grades are more readily available.

The thickness and type of steel substrate are selected on the grounds of mechanical and structural consideration, whereas the thickness of the zinc coating is selected according to the corrosion-resistant life expectancy required.

CORROSION RESISTANCE The protection afforded by a hot dip galvanized coating under normal conditions of exposure is directly related to its thickness. The coating on sheet normally stocked by retailers is Z275, which is suitable for a mild environment. It is recommended that galvanized sheeting be overpainted timeously, preferably before the first appearance of red corrosion products. Where conditions require greater corrosion protection, a thicker class of coating, i.e. Z600, or the addition of a paint coating, should be considered. In the case of the heavier coating, the sheet is not suitable for severe forming other than normal corrugating or curving.

SEPTEMBER 2014

WET STORAGE STAIN (WHITE RUST) When galvanized sheet in coil or sheet packs is stored under wet conditions, the galvanising may be damaged by wet storage staining. Rainwater or water vapour can easily be drawn in between tightly profiled or flat sheets, or between laps of coils by capillary action. Due to the absence of freely circulating air, this moisture cannot evaporate, causing unfavourable conditions that may result in white rust on galvanized sheeting.

Normally, light white staining on galvanized sheet is not serious. The wet storage corrosion process will stop when the affected areas are dried and exposed to the atmosphere. The discolouration will disappear within a few months during the normal weathering of the material. Where affected surfaces will form part of unexposed overlaps or other concealed areas that may be subject to extended periods of dampness, such areas should be cleaned and additionally protected. Galvanized material must, under no circumstances, be stacked directly on a floor.

SURFACE TREATMENT

1. Surface markings from stretcher strain (Lüder’s lines) or fluting when the sheet is formed.

2. Deterioration in ductility.

It is recommended that the period between final processing at the mill and fabrication be kept as short as possible, preferably not exceeding six weeks.

PAINTING Chemical conversion coatings and primers have been developed to provide good adhesion of subsequent paint films on zinc coated surfaces. To obtain optimum results, it is essential to adhere to the instructions of the paint manufacturers.

ZINC COATING MASS IN ACCORDANCE WITH SANS 4998/ ISO 4998 AND SANS 3575/ISO 3575

Passivation by potassium dichromate is normally applied to all galvanized material. In cases where this treatment may interfere with subsequent processing, the galvanized steel may be ordered without passivation, in which case oiling of the zinc surface is recommended.

OILING A special corrosion-preventive oil is used to coat galvanized sheet as an additional protection against wet storage staining during handling and storage.

Oil is only used if requested. If unoiled unpassivated galvanized steel sheet is ordered, proper protective packing should be requested to protect the material against the ingress of moisture during transport and storage.

CUT EDGE CORROSION RESISTANCE The introduction of continuously galvanized coil that is subsequently cut into sheet lengths has tended to focus attention on the behaviour of cut edges which are exposed to atmospheric corrosion. Sheet thinner than 1.6mm is usually adequately protected at cut edges by the cathodic action of the zinc coating. Similarly, side trimmed edges seldom present a corrosion problem. Thicker coatings provide superior cathodic protection.

STRAIN AGEING Galvanized steel sheet tends to strain age and this may lead to the following:

SEPTEMBER 2014

MASS OF COATINGS* EQUIVALENT THICKNESS (BOTH SIDES INCLUSIVE) g/m2, min. PER SIDE ** μm, min

COATING DESIGNATION

Z 100† Z 180† Z 200† Z 275 Z 350 Z 450 Z 600 Z 700

The following surface treatments are normally used to reduce the possibility of wet storage stain during transport and storage:

PASSIVATION

H OT D I P G A LVA N IZI N G

Bend tests to evaluate the adhesion of the zinc coating are carried out and evaluated in accordance with relevant specifications (table 1). In addition to this, impact adherence cupping tests are performed on all products, irrespective of specification, to ensure good adhesion of the zinc coating.

AVERAGE

INDIVIDUAL

AVERAGE

INDIVIDUAL

100 180 200 275 350 450 600 700

85 150 170 235 300 385 510 595

7 13 14 20 25 32 43 50

6 (4,8) 11 (8.5) 12 (9,7) 17 (13,4) 21 (17,1) 28 (22) 36 (29) 43 (34)

Table 1. Mass per unit area of zinc coating.

COATING DESIGNATION

Z1601,2 † Z275 Z6003,4

MASS OF COATINGS* (BOTH SIDES INCLUSIVE) g/m2, min.

EQUIVALENT THICKNESS PER SIDE ** μm, min

AVERAGE

INDIVIDUAL

AVERAGE

INDIVIDUAL

160 275 600

135 235 510

11 20 43

9 (7,7) 17 (13,4) 36 (29)

Table 2. Readily available zinc coating grades in Southern Africa.

NOTES * Not less than 40% of the individual value should normally be found on each surface, indicated in brackets. † Although coating Classes Z100, Z160, Z180 and Z200 are included in this table, these classes are not recommended for bare external applications but have been included for products which would subsequently be further protected by suitable paint systems. ** For information only.

The equivalent thickness is calculated from the following formula: Thickness; μm = Mass per unit area, g/m2 2 x 7 (7 is the approximate specific gravity of zinc) The letter Z in the coating designation indicates a pure zinc coating and the number denotes the total mass of the coating on both faces of the sheet (g/m2) 1. Only available in 0.27 to 0.30mm full-hard material, except Z160 2. Iscor specification only 3. Not recommended for forming grades 4. Not available on full hard material

COATING DESIGNATION

COMMERCIAL STEEL (CS), FORMING STEEL (FS) AND DEEP DRAWING STEEL (DDS) ASTM A653M-97 GALVANIZED SHEET THICKNESS T(MM)

Z275 Z275

0.4 ≤ t ≤ 1.0

1.0 < t ≤ 2.0

0 2

0 2

t>2

1 2

STRUCTURAL STEEL (SS) ASTM A653M-97• GRADE 230

GRADE 255

GRADE 275

1,5 2

2 2

2,5 2,5

•Note: Grades 340 and 550 do not have specified requirements for this property

Table 3. Ratio of the inside bend diameter to the thickness of the specimen.

49

H OT D I P G A LVA N IZI N G

PRIMER-COATED GALVANIZED STEEL SHEET PRODUCED IN A CONTINUOUS COATING LINE (CHROMAPREP®) COATING PROCESS CHROMAPREP® is a registered trade name for cold rolled or hot dip galvanized steel sheet, coated with a high quality, flexible and corrosion-inhibiting chrome-free primer. The substrate is chemically cleaned and treated to ensure good adhesion of the chromate-free primer.

The coating has a nominal thickness of 4-6 micrometres applied by a sophisticated continuous roller coating process, permitting control of coating uniformity and film thickness within narrow limits. The primer coat is finally oven cured and is suitable for overcoating with most locally available finishing paint systems. (Refer to table 4).

CHROMAPREP® is supplied with a chrome free primer on both sides of the steel sheet. CHROMAPREP® with a cold rolled steel substrate may be used for indoor applications while CHROMAPREP® with a hot dip galvanized substrate can be used for both internal and external applications. However, for external uses it is intended that it is used after application of a final paint coating.

TYPICAL PRIMER COAT PROPERTIES Dry film thickness

4-6 micrometres

Heat resistance

180

Resistance to common water based detergents

200

Resistance to mild solvents(1)

275

Flexibility(2)

350

UV-resistance(3)

450

(1) Sensitive to common lacquer thinners, i.e. chlorinated or aromatic hydrocarbons and ketones, but resistant to mineral turpentine, solvent naphtha, methylated spirits and paraffins.

(2) No coating failure or loss of adhesion when bent around a mandrel with a diameter as indicated (T is the thickness of the sheet in mm).

(3) As is the case with most chrome-free primer coatings, CHROMAPREP® is sensitive to ultra-violet radiation and should not be exposed to direct sunlight for prolonged periods before application of the final coating system. When directly exposed to sunlight (ultra-violet radiation) the final coat must be applied within seven days of being exposed.

Table 4.

The liberal use of strong solvents can and will detach the primer coat, which may lead to premature peeling of the paint.

Common lacquer thinners, such as chlorinated hydrocarbons or ketones (MEK) should not be used for cleaning purposes as these may affect the adhesion of the epoxy primer coat.

APPLICATION OF PAINT COATINGS The required paint finish can be applied by normal spray, airless spray or brushing techniques. Usually an additional primer coat will not be necessary, but for most paints a better bond between the CHROMAPREP® surface and the top coat, as well as a higher quality paint surface, may be obtained by application of a primer or intermediate coat for the selected paint systems. Amongst current industrial products, the following paint systems can be applied to CHROMAPREP®: alkyds, vinyls, acrylics, polyesters, powder coatings, stoving enamels, epoxies and polyurethanes.

PAINTED COLD ROLLED GALVANIZED STEEL SHEET PRODUCED IN A CONTINUOUS COATING LINE (CHROMADEK® OR CHROMADEK® PLUS) CHROMADEK® is the trade name for this pre-painted galvanized steel sheet. CHROMADEK® is a colour coat comprising a Z200 hot dip galvanized substrate with a 4 to 6 micron DFT primer underneath the top coat and an 8 micron DFT single coat paint on the reverse side. CHROMADEK® paint is then applied at 20 microns DFT to the top surface (figure 2).

The colour coated products are coated on a sophisticated continuous roller coating line. The modern coating process permits good control of the important painting parameters, and rigid quality control on each finished coil ensures that every batch conforms to specification. Excellent paint adhesion is achieved and corrosion resistance enhanced by careful preparation of the steel sheet under factory conditions prior to paint application. The paint systems are oven cured. The aesthetic appearance and durability of CHROMADEK® cannot easily be achieved by conventional hand painted systems. The coating is highly formable and provides additional protection under conditions where the corrosion resistance of unpainted galvanized sheeting may prove inadequate.

CORROSION RESISTANCE CORROSION RESISTANCE CHROMAPREP® serves as a good corrosion-inhibiting primer coat for subsequent painting. Resistance to corrosion creep is improved by using a galvanized steel substrate, which is strongly recommended for exterior applications.

CLEANING OF PRIMER COAT BEFORE FINAL PAINTING Surfaces should be cleaned by removing surface contaminants by wiping with natural mineral turpentine, solvent naphtha or methylated spirits, followed by a warm water detergent wash and a clean water rinse.

Users are advised to ensure that thinners or adhesives used are compatible with CHROMAPREP®. The CHROMAPREP® primer coat is slightly under-cured to ensure good bonding of subsequent top coats.

50

CHROMADEK® is intended for exposure to rural, mildly chemically polluted or moderate marine conditions. Best results can be obtained through the correct application, good workmanship and maintenance procedures.

NOTE: CHROMADEK® is not recommended for application in marine environments (area approximately 5km from the sea) or exposure to industrial environments where there is an accumulation of strong acid vapours. CHROMADEK® PLUS is recommended for these areas between 1 and 5km from the sea.

CHROMADEK® PLUS is a colour coat comprising a Z275 hot dip galvanized steel substrate, pre-primed on one or both surfaces with 20-25 micron DFT chrome-free universal primer.

Alternatively, only one surface is coated in accordance with the above and the other surface as per the standard CHROMADEK® (4-6 micron DFT). CHROMADEK® paint is then applied to both surfaces, both to 20 micron DFT (figure 2).

SEPTEMBER 2014

The Plus system has excellent physical properties, excellent flexibility, excellent corrosion resistance with excellent resistance to ultra-violet radiation (UV performance). CHROMADEK® PLUS is recommended for exterior building profiles in applications requiring high formability, good gloss retention, high colour stability and excellent corrosion resistance. It is suitable for corrosive environments such as industrial and marine environments. Marine environments can generally be defined as areas within 1km of the sea (table 5).

Resistance to colour Resistance to chalking

TEST METHOD SPECIFICATION TYPICAL CONDITIONS QUV ΔE<5, e.g.

ASTM G154 (1000 hours) change Gemsbok Sand QUV ASTM G154 Rating Range: 1-2 (1000 hours) ASTM D4214

Resistance to corrosion: - Edge creep - Blister size

Salt spray ASTM B117 (1000 hours) After 1000 hours ASTM D714 After 1000 hours

PROPERTY

Flexibility: bend test Flexibility: reverse impact Film hardness Dry film thickness Gloss at 60° At time of coating

≤ 3mm ≤ 8F

3T. No adhesion loss No cracks ASTM D2794 No adhesion loss ASTM D3363 F - H 22μm minimum NCCA 4.2.2 inclusive of primer ASTM D523 25 - 35% ASTM D4145

2mm < 8F 2T. No adhesion loss No cracks No adhesion loss F-H 22μm minimum inclusive of primer 25 - 35%

Table 5: CHROMADEK® paint system properties.

FASTENING METHODS Mechanical fastening systems such as rivets, self-tapping screws, bolts and nuts, spring clips and wire staples can be used, as well as various seaming methods including lockand box seaming. Where protection is needed, fasteners should, where possible, be: • Hot dip galvanized; or • Manufactured from a corrosion-resistant material; or • Electroplated and overcoated with a suitable top coat.

EJOT® The Quality Connection

Further information can be found in the latest copy of SANS 1273.

CUTTING, TOUCH-UP AND MAINTENANCE Abrasive cutting or trimming of CHROMADEK® sheeting on roof tops should be avoided. Should cutting be necessary, remove all iron particles by vigorous brushing with a broom or bristle brush after cutting, to avoid tarnishing the CHROMADEK® paint surface.

In order to site cut a sheet with clean edges and no paint damage, a sheet nibbler is recommended. Specially formulated air-drying touch-up paints are available. Care should be exercised to minimise overpainting, as this might accentuate the defect.

The ultra-violet resistance of air-drying touch-up paints is generally less than the oven-cured CHROMADEK® finishes. Accordingly, touching up of scratches should be done with a thin paint brush to minimise unnecessary overpainting.

If aesthetically acceptable, it is recommended that minor scratches resulting from erection and rough handling be left uncoated as the galvanized substrate will offer adequate sacrificial protection against corrosion.

The life of a CHROMADEK® painted surface can be extended and the appearance maintained by washing down periodically with water and a mild detergent to prevent any build-up of corrosive deposits, especially in marine or industrially polluted environments.

The extent of the damage to CHROMADEK® paint coatings is rather difficult to assess. In cases where the original gloss and colour have been retained, there should be no cause for concern. On proper drying of the moisture contained between closely nestled sheets, no further deterioration will occur.

SEPTEMBER 2014

PAH SALES AGENT (PTY) Ltd Official Sales Agent for EJOT® Tel: +27 (0) 11 394 5721 Patrice.ahmann@gmail.com www.ejot.de

Where discolouration and/or signs of white corrosion products (except cut edges) are evident, such sheets should be substituted with new material.

Certain situations can create unusually aggressive conditions for the exposed, reverse sides of roof sheets.

These include coastal locations (and therefore the risk of saline spray and deposits collecting on the exposed reverse sides of overhangs), extremely polluted industrial environments, and very low pitched roofs. In these or similar conditions, extra protection may be necessary. This can be achieved by specifying CHROMADEK® PLUS to both surfaces.

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H OT D I P G A LVA N IZI N G

COMPATIBILITY Most materials used in contact with traditional galvanized steel can be safely used with CHROMADEK®. Run-off water from Cor-Ten, lead or copper products, however, may cause staining and should not be allowed to come into contact with the painted surface.

EDGE PROTECTION Generally cut edges on CHROMADEK® sheets do not present a corrosion problem even in coastal areas as the galvanized coating will sacrificially protect the exposed steel. Small traces of white deposits on cut edges should therefore, not be a reason for concern.

THE HANDLING AND PROTECTION OF GALVANIZED AND PRE-PAINTED STEEL SHEET DURING STORAGE Galvanized and pre-painted galvanized sheet is known to perform exceptionally well when exposed to the elements.

Under normal wet and dry conditions, e.g. when galvanized sheet is used as roofing and for cladding of buildings, a protective zinc oxide/zinc carbonate layer naturally forms on the exposed surfaces of the material, which improves the resistance against corrosion. In the case of pre-painted sheeting, the protective paint coating offers an additional physical barrier against the elements.

However, the protective nature of these coatings may be seriously impaired when exposed to wet conditions for extended periods in the absence of air. The material is at its most vulnerable during prolonged storage without the necessary precautions.

S-Rib galvanized steel sheeting – Z600 coating classification used for architectural applications.

Rain water or water vapour can easily be drawn in between tightly nested profiled or flat sheets, or between laps of coils, by capillary action (figure 3).

Figure 3.

Due to the absence of freely circulating air, this moisture cannot evaporate, causing unfavourable conditions which may result in wet storage stain, often referred to as ‘white rust’ on galvanized sheeting. In the case of pre-painted sheeting these conditions may cause discolouration of the paint film and in extreme cases wet storage staining, similar to galvanized sheeting.

Wet storage stain may start soon after nested packs or coils of sheet are exposed to wet conditions and may affect the expected maintenance-free life of the sheeting unless arrested at an early stage. The material has to be thoroughly dried and exposed to freely circulating air to stop this corrosion process (figure 4).

STEPS TAKEN TO PROTECT GALVANIZED SHEET AGAINST DAMAGE

BY WET STORAGE STAIN It is standard practice to passivate the surfaces of galvanized sheet by chemical treatment during processing, in order to inhibit the occurrence of wet storage stain. Furthermore, galvanized sheet can be ordered with a special protective oil, which is supplementary to the normal passivation and is intended to provide additional protection during handling and storage.

In spite of these precautions, galvanized sheet cannot be entirely safeguarded against wet storage stain, especially when stored incorrectly under adverse conditions. A special type of packaging is provided for flat sheets and coils. Users who do not have the necessary facilities to temporarily prevent the ingress of moisture are advised to specify such protective packaging.

Every endeavour is taken by manufacturers to ensure that coated sheet products leave the works dry and in prime condition. Such products, whether dispatched in coils or cut lengths, are packed, handled and loaded, under cover, onto vehicles where they are covered with tarpaulins or canopies.

Figure 2.

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SEPTEMBER 2014

Itʼs White Itʼs Green Itʼs Insulation

SAFE STORAGE To prevent unnecessary damage to galvanized or colour-coated sheets, proper measures should be taken to prevent contamination by moisture while the material is still bundled or nested in stacks (figure 4).

works

>

That

If not required for immediate use, coils or packs of sheets must be stacked on site under properly designed cover, clear off the ground and protected from wind-driven rain (figure 5).

Plastic tarpaulins which completely envelop packs of sheets or coils should not be used, as a sudden drop in ambient temperature may cause condensation of water vapour, which can easily be drawn in between nested sheeting by capillary action.

Figure 4.

Figure 5.

Ideally, deliveries of galvanized and colour-coated steel sheet to the building site should be scheduled for a storage period of not longer than two weeks prior to installation. Inspect the storage site regularly to ensure that moisture does not penetrate the stock.

REMOVAL OF WET STORAGE STAIN Wet storage stain should rather be prevented than cured. Although in extreme cases the protective value of the coating may be impaired, wet storage stain attack is often superficial despite the relative bulkiness of the corrosion product. Where surface staining is light and smooth without growth of the zinc oxide layer as judged by lightly rubbing fingertips across the surface, the staining will gradually disappear and blend in with the surrounding zinc surface as a result of normal weathering in service.

When the affected area will not be fully exposed in service or when it will be subjected to a humid environment, wet storage staining must be removed, even if it is superficial. This is essential for the basic zinc carbonate film to form. The formation of this zinc carbonate film is necessary to ensure long-term service life.

Light deposits can be removed by cleaning with a stiff bristle (not wire) brush.

Heavier deposits can be removed by brushing with a 5% solution of sodium or potassium dichromate with the addition of 0.1% by volume of concentrated sulphuric acid. Alternatively, a 10% solution of acetic acid can be used. These solutions are applied with a stiff brush and left for about 30 seconds before thoroughly rinsing and drying.

Unless present prior to shipment from the galvanizer, the development of wet storage stain is not the responsibility of the galvanizer. The customer must exercise proper caution during transportation and storage to protect against wet storage staining.

ArcelorMittal are sheet galvanizing members of the Hot Dip Galvanizers Association Southern Africa (HDGASA).

Article generously supplied by HDGASA.

Insist on EPS Effective Insulation for Walls, Floors and Roofs Expanded Polystyrene, used for thermal and sound insulation in walls, roofs, and floors. Loose beads are used as aggregate in lightweight concrete, plasters and renderings. Also used for underfloor heating systems, drainage boards, permanent formwork, foundations, floatation and prefabricated wall systems. www.epsasa.co.za www.expandedpolystyrene.co.za P. O. Box 7861 | Halfway House | 1685 t: 011 805 5002 | f: 011 805 5033 epsasa@aaamsa.com

SEPTEMBER 2014

growth | development | transformation Towards growth, development and transformation of the Project & Construction Management Professions

Gallagher Estate Midrand, Johannesburg 20-22 October 2014

Book your seat at this pre-eminent learning event aimed at creating collaborative and working relationships for infrastructure development in South Africa and the continent. It is an ideal platform to network and to get in-depth knowledge of stakeholders' view on growth, development and transformation of the construction sector.

Through strategic interventions and partnerships that intend to advance growth, development and transformation of the Project and Construction Management Professions the envisaged outcomes of the Conference are to: • Expose industry players and potential new entrants to the huge government opportunities for infrastructure development; • Facilitate knowledge management and skills transfer in the sector; • Contribute to improvement of standards and benefits to registered persons; • Create a platform for government to engage industry on key infrastructure projects and PPPs for in the SADC region and the continent as a whole and • Create a platform for all stakeholders to discuss ways and means to roll-out a seamless mentorship programme in support of new entrants in the industry.

NEW! NEW! NEW! The 2014 conference will be preceded by Master Classes on 20 October 2014 in the following areas: • Designing Construction Procurement and Contract Management Strategies; • Mentorship and Upgrading from Candidate to Professional Status; and • Construction Health and Safety: ISO 31000, Risk and Hazard Management Standards For early bird registration discounts and more information about the Conference, visit www.sacpcmp.org.za Media Partners:

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Go for gold!

Makita launches their new accessory line-up â&#x20AC;&#x201C; Impact Gold â&#x20AC;&#x201C; into the South African market.

I

mpact Gold is recommended, especially when using high torque impact drivers. This new technology delivers a solution of reducing bit breakage and preventing stripped screws, therefore lowering wastage and generally increasing productivity.

Impact Gold Bits start as high-quality steel and follow a five stage manufacturing process. A corrective stage, engineered to deliver consistent and superior fitment and centering of the bit is included, which produces screw bits for high torque impact drivers that really perform.

Xtreme Torsion Technology allows the bit to flex under load and reduces the pressure off the tip of the bit, thus extending the life of the screw bit by 10 times that of a standard bit.

Impact Gold bits are ideal for demanding applications such as roofing, decking, dry walling framing and more. The bits are available in the standard drive types, with bit sizes of 25mm or 50mm in length, with or without a magnet. Torx bits, used mainly in engineering applications, are also available in sizes ranging from 10 to 30 mm diameter and 25mm in length.

Included in the line-up is the Ultra Mag Torsion Bit Holder, with an extra strong magnet that holds even long screws securely for accurate driving. There is also a Ring Nut Setter that uses a spring-loaded clip instead of a magnet to retain the fastener, eliminating the possibility of debris getting trapped inside the nut setter. A Tilt Socket Adapter is also available that tilts up to a 15 degree angle, making it easier to fasten in confined applications.

If you are looking for fast, clean and effective fastening with extended bit life then the Makita Impact Gold line-up is for you.

SEPTEMBER 2014

SO L A R P V

Johannesburg sees recently completed commercial rooftop

installation with Trina Solar modules The 130kW PV system adds up to the company’s extended list of successful local projects

T

rina Solar Limited, a global leader in photovoltaic modules, solutions, and services, was selected as sole supplier of the 130kW of PV modules for the commercial rooftop project in Johannesburg commissioned at Bazar & Bazar Wholesalers by Eldo Energy.

“Bazar & Bazar Wholesalers, a large fresh and frozen seafood wholesaler in operation since 1985 based near Gold Reef City, commissioned Eldo Energy to design a solar PV power plant which will offset a large portion of its electricity load,” says Tim Ohlsen, Executive Director at Eldo Group. “Based on studies done by Eldo Energy, a 130kW rooftop solar PV system was designed on a combination of IBR and concrete roofing. The solar PV plant will be generating an impressive annual yield of 250 440kWh.” According to Bazar & Bazar Wholesalers, the project was commissioned in order to reduce their overall costs, as well as reduce their environmental footprint. They go on to explain that the installation will decrease operating costs from year 3 onwards, leading to a lower cost base and increased profitability. The installation is expected to save on a total 225 000 kg of CO² per year.

Eldo Energy was particularly considered in their approach to select the right PV supplier. “We chose Trina Solar for their top quality product and professional customer service,” continues Ohlsen. “We found the local Trina Solar team to be extremely helpful in managing the process and ensuring our project timelines were met.”

Comprising of 490 units of Trina Solar DC05A.08-265W monocrystalline solar modules, which are internationally acclaimed for superior efficiency and performance, the project is expected to produce a daily energy yield of 686kWh. Trina Solar is a key innovator in the global solar industry due to the expertise and activities in their State Key Lab of PV Science and Technology. The company – whose advanced technologies in areas such as improving PV conversion efficiency, the lowering of module manufacturing costs and commercialisation of their innovative technologies – is recognised internationally for developments within the field of renewable energy, and continues to develop its business in the uniquely positioned Southern African market.

“The completed installation of another substantial roof-mounted PV system has been an important success for Trina Solar in South Africa, and has assisted in further solidifying our local footprint,” says Ben Hill, Head of Europe and Africa for Trina Solar. “We are confident that the completion of this project, and the imminent conclusion of other key installations currently in development, will positively impact our overall presence in the Southern African PV market,” Hill concludes.

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SEPTEMBER 2014

No matter what, we have you covered Uni-tile, universal grit coated metal roof tiles When you’re looking for roof cover that won’t let you down, Uni-tile from GRS is the really smart way to go. Universally compatible with other popular metal roof tiles, the cost effective Uni-tile is ideal for extension and re-roofing projects, as well as for new roofs. As if that wasn’t smart enough, Uni-tile offers a wider top range for easier fixing to the batten, a wider bottom lip for better water resistance, and a bigger side lap to prevent water leakage.

Available in three standard colours (non-standard colours available on request*), Uni-tile’s 100% acrylic coating can withstand high ultra-violet levels and the most adverse of weather conditions, while the elasticity of the coating prevents the chipping and cracking caused by bad weather. So if you’re looking to go under-cover, get the cover that won’t let you down. Speak to GRS. The smart roof people.

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