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AUGUST 2016 ISSUE: 82
SA R36 EACH INCL. / R360 PER ANNUM INCL.
AUGUST 2016
ISSUE: 82
EDITOR’S COMMENTS................................................................................................. 2 CONTRIBUTORS & EVENTS....................................................................................... 4 INTERACT MEDIA DEFINED...................................................................................... 7 COVER STORY............................................................................................................ 8-9 TIMBER ROOF TRUSSES........................................................................................11-13 LIGHT STEEL FRAME BUILDING....................................................................... 15-16 INSULATION COMPRESSION............................................................................ 19-21 INSULATION WARRANTIES.............................................................................. 22-24 METAL ROOFING...................................................................................................26-27 INSULATION...........................................................................................................28-31 CASE STUDY............................................................................................................33-35 WOMEN IN CONSTRUCTION................................................................................37 BRICK ROOF FEATURE....................................................................................... 38-39 INDUSTRY NEWS........................................................................................................40
SA ROOFING Published By Interact Media Defined (Pty) Ltd Tel: 0861 SA ROOF (0861 727 663) Fax: 0866 991 346 Email: admin@interactmedia.co.za www.interactmedia.co.za Postnet Suite 241 Private Bag X103 N1 City 7463 PUBLISHER Darren Smith dsmith@interactmedia.co.za MANAGING EDITOR Ilana Koegelenberg +27 (0)71 216 814 ilana@interactmedia.co.za ADVERTISING Jacqui Marsh jacqui@interactmedia.co.za LAYOUT & DESIGN Craig Patterson craig@interactmedia.co.za DISTRIBUTION & SUBSCRIPTIONS Belinda Thwesha belinda@interactmedia.co.za COPYRIGHT & DISCLAIMER
While every reasonable precaution has been taken to ensure the accuracy of the advice and information given, neither the editor, publisher, proprietor, staff, nor any official body represented or published in this issue, will accept responsibility for any damages, loss, injuries or false claims that may arise or be made in the content. We subscribe to the Codes of Conduct of the Advertising Standards Authority and the Press Ombudsman (see below). Disclaimers by individual companies are hereby overridden by this disclaimer. Reproduction of any of the content is expressly forbidden in terms of the Copyright Act of 1987 with all amendments. All requests to reproduce must be made in writing to the publisher and such confirmation must be given in writing before proceeding. A copy of where the reproduction was published must be supplied to the publisher at the above address. No reasonable request will be refused provided all conditions are met. PRESS OMBUDSMAN: This publication has committed itself to maintain the highest standards of journalism as embodied in the Press Code of Professional Practice. If you believe we have failed to report news and comment accurately, honestly and fairly, you may lodge a complaint with the Press Ombudsman either by email, fax or letter, or by telephoning the office for the procedure to be followed.
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Tel: 011 484 3612/8 | Fax: 011 484 3612/8 Email: pressombudsman@ombudsman.org.za berylh@ombudsman.org.za Website: www.ombudsman.org.za for the press code This publication subscribes to the Advertising Standards Authority (ASA) Code of Conduct which represents truthful advertising. Should any reader feel or believe that advertising in this publication lacks substantiation, is dishonest or misleading in any way, they may refer to the ASA, www.asasa.org.za.
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EDITOR’S COMMENTS
The right thing at the right time August has arrived.This is an important month for several reasons.
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o start, it is formally (or perhaps not in some of the more brutal climates) the last month of winter. And after a season that bestowed on us some particularly vicious cold and flu strains, it’s about time these short, freezing and often damp days make way for greener days and ways.
Read on to learn more about this very positive change. The established SA Roofing team, alongside some new colleagues, are already hard at work to elevate SA Roofing to an even higher level for the benefit of our readers and advertisers alike – so stay tuned for more to come, on all the right fronts.
Further, August marks two ‘cannot-miss’ happenings on our calendar: The Cape Construction Expo as well as Interbuild Africa 2016. As a media partner to these important industry events, SA Roofing is looking forward to participating and to interacting with you, our valued clients.
One thing that must never change where roofing matters are concerned, is adherence to best practice and other regulations that dictate the standards we must work to. And rightly so – these standards are in place for a reason, safety for all of course being the primary objective. In this edition of SA Roofing, several of our features point to the importance of small print and finer detail that can make the difference between a professional outcome and downright sloppy work that carries potential risk. From proper architectural planning and engineering, to selecting and installing the right products and honouring the criteria of guarantees, it is critical to maintain the integrity of industry standards and best practice. It is the right thing to do.
This is also the month in which we get to exercise our right to vote in the national elections. And, of course August is a great month for all women. I will definitely be taking full advantage of what I consider an official licence to order my husband around for every single one of the 31 days of Women’s Month! Jokes aside, I believe in the potential of every individual, and that the contribution women can make to all facets of life remains vastly untapped. I couldn’t agree more with Elizabeth Gore, entrepreneur-in-residence for Dell, who recently remarked, “Women entrepreneurs are our country's best bet for economic growth.” This month also marks a time of change for SA Roofing: A new publisher is taking over the reins—the well respected Interact Media Defined.
And now, rightly, it is time for me to say goodbye, with an immeasurable amount of thanks to each and every reader for your ongoing support of SA Roofing. It gives me great pleasure to introduce incoming editor, Ilana Koegelenberg, who will from here on be keeping things on the right track. I already look forward to the next issue! Celéste Perrin (outgoing editor)
Reg No: CoR18.3 2013/068719/07
VAT No: 4930188372
MANUFACTURERS OF
QUALITY FASTENING SYSTEMS
Manufactured in Taiwan DBN Branch: Contact: Summers | Tel/Fax: 031 - 765 1604 | Cell: 082 564 1463
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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
CONTRIBUTORS & EVENTS
Contributors DION MARSH Dion Marsh holds a National Diploma in Quantity Surveying and Construction Management. Involved in the roofing industry for close to 25 years already, his extensive experience ranges from contracting to manufacture and supply. More specifically, he has served as a member of the SAMCRA Technical Committee (the Southern African Metal Cladding and Roofing Association) and also as a member of the SANS1273 Working Group. As the General Manager of Ash & Lacy South Africa (Pty) Ltd, a division of Ash & Lacy Building Systems UK, Marsh oversees the operation’s manufacture and supply of innovative and cost-effective building envelope solutions that yield ongoing savings throughout the entire operational life of the building. He works closely with design professionals, property developers, contractors and building owners, offering expert consultation on energy-efficient roofing and cladding solutions that focus on sustainability and the reduction of carbon emissions. Highly skilled in conducting comprehensive roof and cladding refurbishment assessments – including alternative asbestos abatement methods – Marsh is also a noted authority on the groundbreaking Ashgrid spacer system, having played an instrumental role in launching and establishing the system. With his in-depth knowledge of the South African roofing and cladding sectors, Marsh remains committed to providing the industry with premium products, forward-thinking solutions and unmatched customer service.
STIAN DE JAGER In 2004, as part of the practical training required to complete his National Diploma in Mechanical Engineering, Stian de Jager completed the Roof Inspector's Course through Roof Inspection Services (under the tutorship of the late Victor Booth, a Specialist Engineer in Timber Engineering). After his certification, he registered with the ITC-SA as a Qualified Roof Inspector. Whilst completing his Bachelor's Degree in Mechanical Engineering, de Jager actively worked as a roof inspector and formed De Jager Roofs Business Trust in 2007. A partnership with his grandfather Chris de Jager, who came from a municipal building inspector background to become one of the very first roof inspectors, allowed him to further expand on his roof consultancy experience. In 2011, Stian was appointed General Manager for Tlhomeso Timbers and Vertex Roofing Contractors, the largest roof truss manufacturers in Botswana. There, while working closely with professional engineers in the timber roof truss industry on, amongst other projects, roof failures and remedials, he furthered his qualifications to include a 20/20 Advanced Designer Certificate from MiTek. In addition, he was mentored by Cor van Os, a pioneer in the roofing industry, often leading system providers in new concepts and management software solutions. In 2012, he was sent to the USA to oversee the rigging and importing of various types of advanced roof truss manufacturing equipment, including the first TCT automated linear saw. His experience eventually led de Jager to consult for MiTek and other South African truss plants on calibration, fault finding and training related to these saws. De Jager returned to South Africa in 2015 to continue his inspection and consulting work in De Jager Roofs Business Trust. Currently registered with the ITC-SA as a Category A (High Risk: Very Complex) Roof Inspector, he remains committed to add value and make a significant contribution to the industry through his knowledge, experience and skills.
RICHARD POLLING Richard Polling serves MRC Group as the Group Director. He has been a key participant and involved in the construction industry for more than 20 years, working for and with some of the largest manufacturers and contractors in the UK. His practical experience includes designing, manufacturing, installing and maintaining structural steel frames, precast concrete structures, metal roofing and cladding systems, as well as a range of waterproofing systems. As one of the founding members of MRC Group, he is actively establishing new standards and innovations in the African construction industry, endeavouring to constantly lift the bar in design, workmanship and maintenance, thereby protecting clients’ investments for up to 20 years – most recently with the introduction of the innovative Guardian™ Maintenance Scheme.
Upcoming Events TIMBER ROOF STRUCTURE WORKSHOP PRESENTED BY: WOLF PROFESSIONAL SERVICES 18 - 19 AUGUST 2016: CENTURION, GAUTENG 27 - 28 OCTOBER 2016: SALT ROCK, KZN Visit www.wolfpro.co.za for more info
THE INSTITUTE FOR TIMBER CONSTRUCTION (ITC-SA) ANNUAL TIMBER ENGINEERED PRODUCT AWARDS 19 AUGUST 2016 (DURING INTERBUILD AFRICA 2016) EXPO CENTRE NASREC, JHB Email jenni@itc-sa.org for more info
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SAISC STEEL AWARDS 15 SEPTEMBER 2016: TO BE HOSTED IN GAUTENG, KZN & WESTERN CAPE Email marle@saisc.co.za for more info
SACPCMP 4TH ANNUAL PROJECT AND CONSTRUCTION MANAGEMENT PROFESSIONAL CONFERENCE
26 – 28 OCTOBER 2016 SANDTON CONVENTION CENTRE, JHB Visit www.sacpcmp.soaconferences.co.za for more info
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Placed by ENERGY|MC
T +2721 442 5420 F +2721 448 9132 E arno.hanekom@bluescope.com
www.bluescope.co.za
Interact Media Defined purchases Trademax titles Interact Media Defined (IMD) has purchased Trademax Publications’ three titles, effective as of 1 August 2016. This means that Timber iQ, SA Roofing and SA Affordable Housing will now form part of the IMD media offering.
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he Trademax management team has been strategising ways to adapt to the current challenging market conditions while accommodating evolving client needs in today’s fast-paced marketing arena. “The acquisition of the titles by IMD offers an ideal way forward for the publications to grow while capitalising on their established market position and reach,” explains Billy Perrin, founder and outgoing publisher of Trademax Publications. Trademax’s operations will be integrated within IMD and the existing office, along with the sales and operational staff complement in Cape Town, will be retained. This will ensure uninterrupted service and ‘business as usual’ for all existing Trademax clients. In fact, they will soon be able to avail themselves to a broader service offering that includes more advertising choices to fit every promotional budget and promotional strategy. “This is a unique opportunity for our clients to sit back and enjoy a broader service offering without any sacrifice or compromise on quality or delivery,” says Perrin. “The wide scope of additional options that IMD brings to the table will positively benefit every one of our clients, and thereby the industries served.” For IMD, this new venture provides the perfect opportunity to branch out its existing media offering by growing its reach within the building sector. “The three new titles suitably complement our present stable of products and are a testament to the synergies between the two companies,” says Sean Macnamara, managing director of IMD. “This acquisition will also expand IMD’s national footprint, giving us a significant presence in Cape Town for all our titles.” While Billy and Celéste Perrin will be pursuing other interests, the professional and knowledgeable publication managers behind the titles ( Jacqui Marsh for SA Roofing, Kylin Perrin for SA Affordable Housing, and Angeline Martin for Timber iQ), will remain unchanged. IMD’s Ilana Koegelenberg (RACA Journal editor) will step in as the new editor on the titles, ensuring that the publications go from strength to strength.
IMD has purchased the three Trademax titles. Here Billy Perrin, previous publisher of Trademax (left), is with Sean Macnamara, managing director of IMD. “Over the past few months, I’ve become more familiar, and impressed, with the capabilities of IMD. I am very pleased that such a top-class publisher will be taking these respected and established publications to a new level in the B2B marketplace,” says Perrin. The Trademax staff, too, will benefit from being part of a bigger team backed by management philosophies that are not dissimilar to those of Trademax. “I’m looking forward to, in due course, seeing the results of all the exciting initiatives being put into place at this time.” IMD proudly takes a face-to-face approach to business and would like to meet with all key players in the Trademax sphere to build this relationship. Anyone who would like to arrange a meeting is invited to get in touch as soon as possible. To view Frequently Asked Questions (FAQs) relating to this transaction, visit our website www.trademax.co.za.
For more information or to arrange a meeting, contact: Sean Macnamara (managing director) on 0027 (0)82 929 1948 or at sean@interactmedia.co.za.
When measurement matters
To contribute to the editorial calendars of any of the titles, contact Ilana Koegelenberg (editor) on 0027 (0)71 216 814 or at ilana@interactmedia.co.za.
LAMBDABOARD evolution continues to gather momentum
COVER STORY
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Since the introduction of LAMBDABOARD® to the South African market in 2009, the product has enabled the building industry to meet firstworld methods of energy saving. This is thanks to Polyisocyanurate, the world’s preference in rigid insulation, offering the most thermally efficient insulation available in the marketplace: It has the highest R-value per inch of thickness. Leading insulation provider Rigifoam tells us more.
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AMBDABOARD ® is a closed cell, rigid foam board insulation consisting of a foam core sandwiched between two facers. The facers, composed of various organic and inorganic materials, are widely used in residential and commercial markets for roofing, underfloor, as well as side wall applications. Attributes include: • A moisture-resistant foam core. (Optional facers as vapour barrier.) • Compatibility with most solvents used in construction adhesives. • Excellent dimensional stability, thermosetting core; does not soften or melt and drip. • A wide range of service temperatures. • Long-term R-value. • HCFC and HFC-free product with zero ozone depletion potential and global warming potential. • Can be plastered or painted for seamless ceiling applications.
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DON’T OVERLOOK INSULATION Insulation is the hidden energy saver that seems to be overlooked at the time of design. Then, when it is included, price dictates and it ends up being considered a ‘waste.’ Like all things in life, quality comes at a price, and return on investment is key. With electricity supply being an issue, not to mention ever-increasing costs, thermal insulation should never be compromised. Cheap insulation mediums don’t last – they become ineffective over a short period of time. LAMBDABOARD ® is fast becoming the number one choice for rigid insulation, as no other insulation medium can match all of its attributes in another single product. Rational designs are proving that, by using LAMBDABOARD ®, only 60% of deemed R-values are required as per SANS10400-XA requirements. And – what you see is what’s installed! Unlike radiant barriers or bulk insulation, it is not reliant on a fixing method to perform.
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COV E R S TO RY With branches in Johannesburg, Durban and Port Elizabeth, and distribution centres in Cape Town, Bloemfontein, Pretoria, Windhoek and Gabarone, supply and site services are made easy. And the ease of supply is further supported by various national roof sheeting suppliers that distribute LAMBDABOARD ® to site along with roof covering.
LONG-LASTING AND RELIABLE Recent case studies have shown that, after 34 years of Polyisocyanurate being installed in South Africa at an international brewery site, the board is still in its original form and performing as designed and installed to do. More than 400-million square metres of Polyisocyanurate get installed annually in the North America roofing industry. That is upwards of 80% market share – and growing. In South Africa it is a new product by name, but it is actually not new as a generic product. It has been supplied for more than 50 years already, although in the early days insulation at the time was not seen as an essential requirement.
MARKET LEADER Rigifoam (Pty) Ltd., a South African company, is the producer of LAMBDABOARD ® and other thermosetting products for the building and cold chain industries, and is widely recognized as the market leader in technology, new product development, and quality. “We are not order takers; we help tailor products to meet market demands,” says Duncan Goldsmith, Co-founder and Managing Director of Rigifoam. “With over 100 years of combined product knowledge and applications, we are a member of numerous international associations (with a presence on technical boards) and pride ourselves in the acceptance of our products and market share in such a short period of time.”
Over the decades, thermosetting products have proven themselves to be the pinnacle of insulation mediums, used in the following industries and applications: cold chain, chilled water piping, pipe saddles, petrochemical plants, food processing plants, hot water boilers (geysers), commercial and industrial refrigeration. Only one question remains. Do you have LAMBDABOARD ® in your building?
FOR MORE INFORMATION: Rigifoam (Pty) Ltd. Duncan Goldsmith (e) duncan@rigifoam.com (t) 011 421-0313 (w) www.rigifoam.com
Goldsmith says Rigifoam’s proven technology and service is unmatched compared to cheap alternatives exaggerated by false sales claims.
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TI M B E R ROO F TRU S S E S
Benefits of prefabricated timber roof trusses The Institute for Timber Construction (ITC-SA), South Africa’s professional body and regulator of the engineered timber structure industry, offers insight into the benefits of prefabricated roof trusses and how to prevent costly and potentially dangerous situations arising from having a non-compliant, site-manufactured roof installed by an erector that is not ITC-SA accredited.
A fully compliant roof structure as manufactured by a professional member of the ITC-SA. (Image credit: BUCO KZN.)
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he roof structure can be considered as one of the most important building elements of any residential building to be constructed. It protects the occupier’s property, finishes and inhabitants from the elements. It is also one of the largest, heaviest and most costly structural components in any home design.
ITC-SA ACCREDITED FABRICATORS
It is therefore logical to expect that thorough planning, design and know-how would be invested in the project in order to create an attractive, sound structure that can safely carry the induced loading as well as offer acceptable longevity and aesthetic appeal for the lifespan of the building. Yet, sadly, many building owners choose price over quality when it comes to both workmanship and materials. And this can lead to costly, disastrous and sometimes even life-threatening situations.
An annual Certificate of Competence is issued by the ITC-SA to confirm that the fabricator complies with the National Design and Material Standards as well as the ITC-SA requirements.
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Each and every ITC-SA accredited fabricator is audited yearly in terms of quality, competence and compliance to, inter alia, the South African National Standards – SANS10243: The Manufacture and Erection of Timber Roof Trusses.
Prefabricated roof trusses shall, at all times, be in accordance with the rational design requirements given by the engineer, as well as the following SANS requirements.
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TIMBER ROOF TRUSSES
A fully compliant roof structure as manufactured by a professional member of the ITC-SA. (Image credit: HF Roofs.) To confirm compliance, an engineering certificate will be required on completion of any roof structure: • SANS 10400 - Part L • SANS 10243 • SANS 10163 • SANS 1783 - Part 1 and 2 • SANS 51075 • SANS 3575 • SANS 10096 Prefabricated roof trusses can only be approved when a rational design is available, confirming that the material and truss design meet and/or exceed the SANS requirements.
ESSENTIALS OF A SOUND TIMBER ROOF
An example of a site-manufactured roof structure that will threaten life and limb. The ITC-SA makes sourcing of reputable roof fabricators, erectors, inspectors and engineers easy – its website provides a comprehensive list of all accredited members on a national basis.
1. The timber used must be structural timber and must comply with the material and, where applicable, treatment requirements, to meet the design intent: Structural timber needs to be marked with red ink on the face of the timber at 1m intervals. If it does not bear Note: The metal connector plates used must be supplied by these structural markings, it will need to be rejected. the specific software system that was applied in the design. In Consumers are cautioned to be wary of unmarked timber addition, the metal connector plates must be the right size, or timber with black crosses at the end: This marking, or positioned correctly, and located as per the standard methods lack thereof, confirms that the timber in question is not and tolerances prescribed by the system. Furthermore, it is structural timber. critical to note that teeth direction on the connector plate(s) is also important – only a cutting bill can confirm this. 2. The designer must create an accurate cutting bill: 4. All connections and bracing details must be in The cutting bill will dictate the exact lengths and angles at accordance with the rational design intent: which the timber must be cut for proper assembly. In other words, everything that holds the structure together, such as the number of nails, bolts, washers, 3. The right engineering systems must be used: brackets and cleats, must be in accordance with the The ITC-SA provides accreditation for three systems engineering design. All necessary bracing accessories that are recognized for meeting all South African must be stipulated on the design drawings. prescribed design and manufacturing requirements: • MiTek Industries SA (Pty) Ltd. • International Truss Systems (Pty) Ltd. • Multinail Africa (Pty) Ltd.
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PITFALLS OF NEW TIMBER ROOF STRUCTURES • Choosing price over quality The saying ‘you get what you pay for’ could not be more true than in the case of a timber roof construction. Many consumers try to save on the roof construction but often end up spending more time remedying the consequences that result from using substandard materials and workmanship. To achieve a professional and sound end result, you will need to employ qualified, knowledgeable and experienced professionals, which will no doubt cost more initially than non-qualified individuals off the street. But this decision will save a lot of money and stress down the line. • Choosing the right engineer Use an Engineering Council of South Africa (ECSA) registered professional, who is accredited with the ITC-SA to design and certify the timber roof structure. Ensure that your chosen professional has a good working knowledge of timber and roof construction. • Prefabricated roof trusses are preferred Prefabricated roof trusses are cut by advanced, specially designed machinery and are therefore far more accurate than their handmade counterparts. Assuming they are designed by an ITC-SA accredited professional, prefabricated trusses covered by a rational design will also use less timber and will comply with all regulatory requirements. In all industry-related tests, the ITC-SA has found sitemade timber trusses to be more expensive than premanufactured timber roof trusses. • Guarantee By using reputable fabricators, such as those registered with the ITC-SA, the consumer can immediately have peace of mind that these companies or individuals are regularly audited and monitored, and that should something go wrong with their workmanship, the consumer will have recourse in the form of a manufacturing warranty. Part of the membership requirements for engineers accredited by the ITC-SA is that they all carry their own professional indemnity insurance cover for any professional negligence on their part with regards to the specific structures they sign off and take responsibility for.
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IMPORTANT TO NOTE • Internal investigations and findings by the ITC-SA have confirmed that 90% of handmade/site-made trusses do not comply with the relevant building regulation and SANS material and design specifications. • Research suggests that handmade/site-made timber roof trusses are, on average, up to 20% more expensive than premanufactured timber roof trusses. • Prefabricated roof trusses come with guarantees in the form of a manufacturing warranty and an engineer’s design certificate, which the owner may call upon to have the roof structure repaired. It is important to note that the so-called ‘engineer’s certificate’ so often referred to on quotations, refers to the certificate which certifies that the timber structure has been erected according to the design intent. In addition to this, the owner should insist that the fabricator prove that the roof structure has been designed according to a rational design.
For more information, visit www.itc-sa.org.
TEL : 021 845 5551 • FAX : 021 845 5556
www.ROOFTEK.co.za KALAHARI BRUWER
kalahari@rooftek.co.za 083 458 7122
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Innovative. Sustainable. Complete.
Innovation is at the heart of our priorities. Our extensive product range blends sustainability and architectural creativity to inspire better ways of building and living.
Our Fibre Cement Facades, Fibre Cement & Gypsum building boards and Roofing solutions put us in a unique position to contribute to complete solutions for building projects
Tel: 011 316 2121 Fax: 011 316 4138 Web: www.marleybuildingsystems.co.za
LIGHT STEEL FRAME BUILDING
Lightweight steel frame construction gains impetus with Marley Building Systems The quality, cost and time efficiencies of light steel frame construction outweigh any and all of the traditional brick and mortar values, says Marley Building Systems, and yet this building method is taking time to become entrenched in the South African building industry. What is needed is a paradigm shift towards an environmentally conscious mindset, which Marley Building Systems is actively motivating.
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ight steel frame construction is an alternative, energyefficient method of building that has been used for decades in the USA, Europe and Australia. Admittedly, in relation to our international counterparts, the South African market is still in its infancy, but the burgeoning energy and water crises being faced by our country will undoubtedly expedite the demand for this seamless, dry construction building system. When Marley Building Systems acquired the Lafarge Gypsum business in South Africa in November last year, the company also took on the light steel frame manufacturing division of that organization. This component of the business was an ideal match for the innovative, sustainable and complete building solutions offering from Marley Building Systems, as a leading supplier of superior roofing, cladding and dry construction solutions.
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Clarence Kachipande, Marley Building Systems’ Specifying Manager: Commercial, said: “As innovation remains a key focus at Marley Building Systems, we have understood that IBT (Innovative Building Technologies) will increasingly continue to play a significant role in the delivery and provision of critical built environment infrastructure.” Recently the South African government passed a resolution that 60% of all new social infrastructure projects are to use such alternatives, meaning the usage of building materials other than brick and mortar. “As an architect, I believe that if we are to shape truly sustainable quality environments, they must be those that are comfortable and evoke feelings of delight and satisfaction, but most importantly, they must be humane.”
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LIGHT STEEL FRAME BUILDING
The Marley Building Systems’ light steel frame solution is made from galvanized steel of minimal 0.8mm gauge thickness, resulting in load bearing and strengths of up to 550mpa. It comprises of an 89mm X 41mm C-section profile with studs spaced at either 400mm or 600mm centres, depending on the structural requirements. The system is clad with a water-resistant material externally (for example, Kalsi fibre cement boards). The insulation (wall batts) is inserted between the studs, and, finally, internal cladding with 15mm Siniat Fire Check plasterboard meets fire safety performance requirements while achieving a perfect finish.
Light steel frame structure for a 42m2 house.
The initial design has to be fulfilled by a professional such as an architect or engineer. The plumbing and electrical designs are submitted by the respective professionals and then collated by the architect. On completion of the design, a structural engineer is required to certify the structure. Light steel frame structures offer a number of distinct advantages, including: • Greater flexibility in spatial design than conventional building materials. • Buildings can easily be extended without major costs, and most of the material can be reused. It is a messy and more difficult process to extend conventional buildings, often resulting in structural cracks that tend to appear at the junction between the existing building and the new extension. • Superior fire resistance, thermal comfort and acoustical performance can be achieved in the design without incurring major additional costs. • A fast and effective add-on storey extension solution to existing buildings (masonry or steel frame) with minimal or zero interference to the structure or its users. • Unlike conventional buildings, internal layouts can be easily reconfigured by shifting walls at a later stage, with minimal pollution to the environment – and therefore a reduced health risk to occupants (e.g. negligible dust).
Marley Super 6 of 3600x920x6mm barge boards; 80x200x3000 Marley Super 6 Ridge LD & RD were used for the roof.
Marley HD fibre cement boards of 3000x1200x9mm fixed to steel frames with jackpoint screws. All joints were fibatape expressed and filled with a suitable compound for external cladding.
To demonstrate the ease of installation, Marley Building Systems will be assembling an ecofriendly steel frame home at the upcoming Interbuild Africa exhibition in August. Professional representatives will be on hand to answer questions regarding the light steel frame method of building for both residential and nonresidential purposes. For more information, contact Ayanda Ndlovu, Communications and Product Manager, at ayanda.ndlovu@marley.co.za or (011) 316-2121.
Fire check plasterboards of 2700x1200x15mm were fixed to steel frames with jackpoint screws. All joints were fibataped and ultimately plastered with premium jointing compound for the internal cladding of the house.
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Metalforming Technology SA build, supply and manufacture machinery for the steel industry. We also custom design and build machines to suit the client’s needs. Our rollformers are pre-engineered to suit the client’s specifications. Quality parts can be produced using our equipment. This where tight tolerances are required on lengths, width and punching configurations with different patterns and sizes. We offer complimentary machines used in steel production for all applications from forming, shaping, slitting, bending, cutting, notching and steel coil processing.
Metalforming Technology is the supplier of first class machinery used in the Roofing, Automotive, Steel door, Window and Garage doors manufacturing industries. From fencing, purlines, guard rail to steel profile or processing, including automotive parts and many other types of applications. These machines are build to process different types of steel from black steel, stainless, aluminium, copper to hard marine steel materials. Provide us with your specifications and let is build you the right equipment to your requirements.
METALFORMING TECHNOLOGY SA (PTY) LTD Phone: +27 (0) 72 738 6360 +27 (0) 83 273 8322 +27 (0) 21 981 6780 Email: sales@mftsa.co.za Website: www.metalformingtechsa.com
I N S U L ATI O N CO M PR E S S I O N
Dissecting the effects of compression Recent 2D thermal simulations carried out on common South African roof assembly details have provided valuable new data on the detrimental effects that compression of bulk insulation has on the overall thermal performance and energy efficiency of roofs. Dion Marsh tells us more. Article and images provided by: Dion Marsh, General Manager of Ash & Lacy South Africa (Pty) Ltd.
Insulation over purlin with no spacer.
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he prescriptive route of compliance in SANS10400-XA stipulates that a prescribed total minimum R-value be achieved in roof assemblies based on the building classification and geographical location. It is widely accepted that the most efficient location for insulation is over purlin. A continuous layer of insulation is achieved and, if installed correctly, it eliminates thermal bridging almost entirely. Bulk insulation blankets or quilts provide a cost-effective and flexible solution in achieving these prescribed R-values. However, the insulation needs to maintain its thickness and position throughout the building envelope assembly in order to achieve its designed thermal resistance. Compression of insulation will proportionately lower the thermal resistance of the material, resulting in a reduced thermal performance. It is still common practice for glass fibre blankets or quilts to be installed over purlin below a single skin steel roof assembly without the use of a roof spacer system. The insulation is supported by basic straining wire and draped between purlins to allow for some recovery in the material’s loft. Variations of this detail utilizing continuous XPS or timber packers are sometimes employed to improve loft recovery, but these methods still result in varying degrees of compression.
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These roof assembly details have been the topic of discussion at both TIPSASA (Thermal Insulation Products & Systems Association SA) and SAMCRA (Southern African Metal Cladding and Roofing Association) technical committee meetings, and have come under increased scrutiny. The question being asked is whether the current construction details and methods being used are achieving the prescribed minimum requirements stipulated in the National Building Standards.
COMPRESSION TESTS A recent series of compression tests were commissioned by Ash & Lacy Building Systems Ltd UK and carried out by Oxford Brookes University to establish the effect of compression on the thermal conductivity and thermal resistance of a glass fibre quilt under these particular site assembly conditions. The tests revealed that, when fixed directly below a steel roof sheet and/or packer, a 155mm glass fibre quilt with a density of 12kg/m3 is compressed at the purlin to a thickness of less than 5.0mm, resulting in a density of 328.6kg/m3.
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INSULATION COMPRESSION
Insulation over purlin with XPS or timber packer. The thermal conductivity of the compressed insulation increased marginally from 0.038W/mK to 0.046W/mK, whilst the thermal resistance decreased dramatically from 4.079m2K/W to 0.109m2K/W. South African Building Standards stipulate that an overall minimum R-Value has to be achieved by building envelopes, but allows for insulation to cross purlin lines provided that a thermal break of 0.2m2K/W is introduced. The Oxford Brookes University test results confirmed that a compressed 155mm, 12kg/m3 glass fibre quilt between a single skin steel weather sheet and purlin does not achieve this required thermal break requirement. The results of the Oxford Brookes University tests, coupled with a distinct lack of credible thermal performance data on SA roof assemblies, prompted Ash & Lacy South Africa to undertake an accurate thermal simulation study using THERM 7.4.3.0 Thermal Simulation Software developed at Lawrence Berkeley National Laboratory. The aim of the study was to produce a comprehensive set of accurate and definitive thermal performance data for commonly used insulated roof assemblies in SA by means of thermal modelling, utilizing data obtained from practical field mock-ups, case studies, accredited thirdparty test results, and published material properties.
TEST RESULTS A total of twelve (12) roof assemblies were modelled and simulated. Nine (9) of these assemblies were based on actual assemblies commonly used in South Africa whilst three (3) models were based on theoretical assemblies with a continuous uncompressed layer of insulation with no thermal bridges. The simulation results of the actual assemblies were compared to the theoretical assemblies to show the percentage of total R-value loss. 1. The percentage in R-value loss varied dramatically, ranging between 2% - 72% depending on the assembly, the presence of a spacer system, the type of spacer system, and the extent of compression incurred by the insulation.
Example of flux vector paths at purlin lines. 3. A similar pattern in flux vector movement occurs in assemblies where the insulation is compressed below the XPS packer/spacer. Although the XPS packers have an excellent thermal resistance, the compressed insulation that exits from below the packer on either side of the purlin is only 4mm - 5mm thick, with a thermal resistance of between 0,086m2 .K/W - 0,108m2 .K/W. A significant amount of thermal bridging occurs at these lines. The flux vector movements in the simulation are concentrated in these areas. Another significant result of the simulation was the flux vector paths at mid purlin. These vectors, which would ordinarily have had a more vertical path, tend to travel more horizontally within the insulation directly below the steel roof sheet – in a path that gravitates towards the air gaps and compressed insulation at, and adjacent to, the purlin lines. This increased thermal movement gravitating towards the purlin lines also results in thermal movement diagonally through the sides of the XPS packers where their thickness is only a percentage of their overall depth. 4. Only three (3) out of the nine (9) typical assemblies achieved an R-value percentage loss of less than 5%. These were the assemblies that utilized a bar and bracket-type mechanical spacer system, which does not cause compression of the insulation at purlin lines. The fractional R-value losses incurred by these assemblies were attributed to small air gaps below the profiled bars and a thermal bridging percentage of approximately 0.1% at the bracket positions.
2. The simulated flux vectors and isotherms revealed that a significant amount of thermal movement (bridging) occurs at the purlin lines when the insulation is compressed directly below a roof sheet.
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I N S U L ATI O N CO M PR E S S I O N
SUMMARY OF SIMULATION TEST RESULTS DESCRIPTION OF ROOF ASSEMBLY
TOTAL R-VALUE (ACTUAL) m2 .K/W
R-VALUE PERCENTAGE LOSS %
75mm Glass Fibre 12kg/m3, Over Purlin 1800mm Centres, Uncompressed (Theoretical), Concealed Fix Weather Sheet
2.1451
0% LOSS
75mm Glass Fibre 12kg/m3 Over Purlin, 1800mm Centres , Concealed Fix Weather Sheet
1.0043
53% LOSS
75mm Glass Fibre 12kg/m3 Over Purlin 1800mm Centres, 40mm XPS Spacer, Concealed Fix Weather Sheet
1.8114
16% LOSS
75mm Glass Fibre 12kg/m3 Over Purlin 1800mm Centres, 85mm Ashgrid Spacer, 10mm Airgap, Concealed Fix Weather Sheet
2.1165
1% LOSS
135mm Glass Fibre 12kg/m3, Over Purlin 1500mm Centres, Uncompressed (Theoretical), Concealed Fix Weather Sheet
3.7435
0% LOSS
135mm Glass Fibre 12kg/m3, Over Purlin 1500mm Centres, No Spacer, Concealed Fix Weather Sheet
1.0341
72% LOSS
135mm Glass Fibre 12kg/m3 Over Purlin 1500mm Centres, 40mm XPS Spacer, Concealed Fix Weather Sheet
2.6077
30% LOSS
135mm Glass Fibre 12kg/m3 Over Purlin 1500mm Centres, 75mm XPS Spacer, Concealed Fix Weather Sheet
3.1181
17% LOSS
135mm Glass Fibre 12kg/m3 Over Purlin 1500mm Centres, 135mm Ashgrid Spacer, Concealed Fix Weather Sheet
3.6425
3% LOSS
150mm Glass Fibre 12kg/m3, Over Purlin 1500mm Centres, Uncompressed (Theoretical), Concealed Fix Weather Sheet
4.0972
0% LOSS
150mm Glass Fibre 12kg/m3 Over Purlin 1500mm Centres, 75mm XPS Spacer, Concealed Fix Weather Sheet
3.3288
19% LOSS
150mm Glass Fibre 12kg/m3 Over Purlin 1500mm Centres, 150mm Ashgrid Spacer, Concealed Fix Weather Sheet
4.0343
2% LOSS
IMAGE OF ROOF ASSEMBLY
CONCLUSION SANS10400-XA stipulates that a prescribed minimum total R-value be achieved based on the building classification and geographical location. These minimum requirements are not being achieved in a large majority of new buildings being constructed in South Africa, due to compression caused by incorrect installation methods. This negatively impacts on the overall energy efficiency and associated operational costs incurred over the life cycle of the building.
Insulation over purlin with bar & bracket spacer.
The additional costs associated with the incorporation of a suitable spacer system into the roof assembly design remain negligible when considering the cost savings achieved by insulation that ultimately achieves its full design capability over the life cycle of the building.
With proven installation methods and tighter on-site quality control, bulk insulation, whether used in single skin or dual skin applications, can still achieve its well earned reputation as an affordable solution in achieving excellent thermal, acoustic and fire performance.
Achieving energy-efficient, structurally sound and compliant roof assemblies no longer has to be an onerous task for professionals and contractors.
For more information, the author, Dion Marsh, can be reached via email to Dion.Marsh@ashandlacy.com.
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INSULATION WARRANTIES
The devil’s in the detail A review of key metal roof system elements and their associated guarantees leaves the question: Are clients getting the warranties and long-term performance that they are paying for? In this article, Richard Polling addresses the holistic design of metal roof systems and important implications for the long-term performance of insulated roof systems. Article by: Richard Polling, Group Director - MRC Group South Africa Photographs courtesy of MRC Group.
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ong-term metal roof system failure is all too common in Southern Africa, generally due to poor quality design and construction of perimeter and penetration details, which leads to water ingress resulting in damage within the building. But the implications reach much farther than that.
WATER INGRESS IMPACTS INSULATION GUARANTEE Water ingress in any form into the building has lasting implications for the guarantee of the performance of your installed bulk insulation blanket system.
Photograph: © MRC Group
Failed open end lap, allowing the ingress of wind-driven rain.
A closer look at the guarantee on bulk insulation blanket products clearly shows that the thermal, acoustic and fire performance of the insulation can only be guaranteed if certain conditions are met, such as: • The product must be stored, handled and installed in accordance with the manufacturer’s instructions. • No physical damage is caused to the product during either installation or during its operational life. • There is a recorded maintenance plan to show the product has been maintained according to the manufacturer’s recommendations. • There is no water ingress or other liquids present due to leaks or any other manner that will cause loss of insulation properties. Meeting all the above conditions is vital in order to keep the validity of the installed insulation guarantee, and yet many roofs leak – thereby invalidating this guarantee. The impact on the thermal and acoustic performance of the insulation from water ingress may not be felt for many years; however, the fire performance may be impaired when you most need it. To ensure the validity of the insulation’s guarantee as well as its long-term performance, a recorded maintenance scheme (such as the Guardian™ Maintenance Scheme offered by MRC Group) needs to be in place for the complete roof system.
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Photograph: © MRC Group
Essential recorded maintenance of the roof system.
Photograph: © MRC Group
Breakdown of the end lap from rust under the waterproofing.
Photograph: © MRC Group
Water vapour sealed within the end lap by the waterproofing has accelerated the corrosion process.
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I N S U L ATI O N WA R R A NTI E S
Note: The abovementioned areas of risk are not generally covered in the guarantees from the various manufacturers and contractors. And, if they are covered, it’s usually only for a few years, thereby passing on the risk of long-term poor performance to the client.
THE RISKS
Photograph: © MRC Group
The corrosion process between roof sheets without butyl seal type sealants.
HOW BIG A PROBLEM IS WATER INGRESS? There are many high-quality roof systems on the market, including pierced fix, concealed fix and secret fix systems – all in a myriad of arrangements to provide a large range of solutions. Provided such a quality roof system is specified correctly, constructed correctly with all the various elements and with the correct gauge and girth of the perimeter details, and that the roof system is regularly maintained, the roof should not leak – and therefore the insulation guarantee will remain valid. MRC Group’s knowledge of the manufacturing, installation and maintenance of all types of metal roof systems is extensive, borne from extensive experience in the refurbishment, upgrading and maintenance of industrial, commercial and retail buildings. MRC Group’s unique roof auditing and diagnostic services of existing roofs highlight all the water ingress issues and their potential solutions, before any specifications can be written or works undertaken. MRC Group has completed numerous audits of large-scale roofs, on both newly constructed buildings as well as roofs that had been installed many decades ago. In most of these cases, the roofs had not been maintained and have leaked, effectively invalidating any guarantees given at the time of installation.
WHERE DO ROOFS LEAK? Although incorrect specification does occur, the main reason for water ingress or leaks is a lack of care regarding the details. Roof sheeting from the major manufacturers is generally fit for purpose and, if installed correctly with all the various elements, will not leak; however, the poor quality of installations is the biggest factor that leads to water ingress. Risk areas, or where water ingress or leaks are most likely to occur, include: • Roof sheet end laps. • Perimeter details such as ridges, headwalls, barges and sidewalls. • Penetration details for pipes, flues and other such items. • Roof light sheeting solutions. • Exposed fixings loosened through thermal expansion. • Roofs that are not maintained.
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• Roof sheet end laps and side laps: It is considered best practice to install butyl seal type sealants to both the side laps and end laps of pierced fix roof systems, and essential for roof pitches below 7.5 degrees. Should water ingress occur through these joints, it is because it is not common practice to include these sealants. When a leak in the lap is discovered during the operational life of the roof, it is common practice to seal the joint from the exterior with a waterproofing membrane; however, the water vapour now encapsulated within the joint forms a more corrosive environment as it warms up and cools down, thereby speeding up the corrosion process on the end lap of the roof sheet, causing more leaks and now making the roof sheet dangerous to transverse during maintenance. • Perimeter detail flashings: The manufacturers provide an indicative principle of how the detail should be formed, but in no way must a ‘one size fits all’ solution be applied. In most cases, ridge, barge and changes in angle metal flashings are under-gauged and the girth is undersized, which leads to problems of water ingress by wind-driven rain. Example: A roof with a low roof pitch should have a larger girth ridge flashing, and therefore a thicker gauge of metal. This is to stop the impact of wind-driven rain, which can be a big contributor to water ingress into low-pitch roofs. Many of the metal flashings installed around roof details have a girth of 462mm, for no technical reason other than the fact that two flashings can be made from a single 925mm-wide flat sheet, keeping waste and costs to a minimum – with no consideration given to long-term performance. In most cases, the audits of existing roofs undertaken by MRC Group have exposed the fact that many of the elements that make up the perimeter details were not installed correctly or not installed at all. These include the important profiled foam fillers or polyclosures, tapes and sealants, all of which should be hidden, if they were installed, once the actual metal flashing is secured. It is interesting to note that, in general, the manufacturer will provide a long-term guarantee for the material itself, but it is the approved contractor’s responsibility to provide the roof systems performance warranty against water ingress. Such warranties are normally less than five years, thereby exposing the client to the risk of long-term poor performance and invalidation of the insulation guarantee. • Penetration details: There are many roof systems that can be installed down to extremely low roof pitches, such as the ‘secret’ or concealed fix systems that provide the benefit of no exposed fixings and long sheet lengths, removing the requirement for end laps. But, as soon as a penetration such as a vent, pipe or flue is installed, the risk of water ingress is dramatically increased.
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INSULATION WARRANTIES
Should a building require penetrations through the roof, either an alternative roof system such as a single-ply waterproofing membrane should be considered, or the roof pitch should be increased to mitigate the risk. The lower the roof pitch, the more reliance placed on the tapes and sealants to oppose water ingress from wind-driven rain. With the use of an aluminium roof system, there is the additional benefit of being able to weld up the flashing detail to ensure no water ingress.
MITIGATING THE RISKS FOR THE BUILDING OWNER To ensure a high level of construction compliance, it has to be the responsibility of the manufacturer and the contractor to ensure the correct application of the roof system and the installation of all the components that make up the roof system and its associated perimeter and penetration details.
Photograph: © MRC Group
Due to the low roof pitch 925mm girth metal ridge flashing complete with serrated closures, polyclosures, sealants and turnups in lieu of the standard 462mm girth metal ridge flashing.
Such compliance should be substantiated with regular photographic reports during installation that show how the roof system has been installed as well as all the components that make up the perimeter and penetration details. All guarantees provided by both the manufacturer and the approved contractor should be for the same length of term. In other words, if the roof sheet material guarantee is for 15 years, the approved contractor should provide a 15-year guarantee for the performance of the roof system, including his workmanship. All guarantees should specifically mention the following items: 1. The length of term of material guarantee and the expected operational life of each of the roof system components: a. Roof Sheeting b. Tapes and Sealants c. Fixings and Fasteners d. Insulation e. AshGrid Bar and Bracket Support System (if used) f. Straining Wire or Liner Sheet (if used) g. Perimeter Flashings h. Penetration Flashings
Photograph: © MRC Group
Standard waterproofing solution to water leaking through the end lap.
2. Correct application of the roof system. 3. Construction compliance of all the components that make up perimeter details. 4. The length of term of the warranty of the workmanship. (This should match the length of term of the material guarantee.) 5. The length of term of the guarantee of no water ingress from normal weather conditions. For more information, contact the author, Richard Polling, on cellular (0)79 340-2318 or via email to richardp@mrc-group.co.za, or visit www.mrc-group.co.za. MRC Group offers the Guardian™ Maintenance Scheme, an innovative single-source, transferable building envelope warranty that covers up to 20 years of the building envelope’s life, providing coverage not only for materials and workmanship, but also maintenance. Photograph: © MRC Group
Fire damaged building. Was the insulation guarantee valid?
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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
METAL ROOFING
Concealed fix and standing seam roofing – value engineering at work Today's drive to design buildings that reduce environmental impact is helping to elevate the metal roofing market to new heights. Most large roofs are concealed fix roof systems (also called secret fix systems). In principle, they provide some common benefits. Safintra, leading provider of world-class roofing systems, tells us more.
BENEFITS OF CONCEALED FIX The sheet is fixed to the purlin with a clip system. The sheet hides the clips completely, providing a neat, watertight and noholes roof, which eliminates the risk of leaks. Metal expands and contracts at about 1 millimetre per metre. The clips allow the sheet to thermally expand over the clip in a sliding movement, so very long lengths of continuous sheeting can be installed with no end laps, thus providing further weather-tightness.
Aside from the profile itself, it is the clip designs that distinguish concealed fix metal roofing systems from each other. One of the biggest benefits of concealed fix roofing is the wind-uplift performance that gets achieved. No two roofs are the same, and most roofs experience several different areas of wind pressure, whether negative or positive pressure. The material thickness of the clip (gauge) helps determine its inherent strength, which in turn helps to determine the minimum wind-uplift resistance requirements for a particular roof.
From a performance point of view, however, the secret is not that the sheet is secured by an unseen clip, but rather the engineering of the clip and its fit with the profile of the sheet.
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METAL ROOFING
VALUE ENGINEERING For all roofing systems, energy payback is derived almost exclusively from R-value, and R-value is derived almost exclusively from insulation. A high-performance metal roofing solution is among the best ways to protect that investment. Once a customer understands how much of his R-value investment is lost once water penetrates the insulation, the added protection provided by a high-performance roof becomes apparent. In the realm of roof performance, reducing upfront costs for short-term savings inevitably leads to escalating costs and liability down the road. Learning to analyse the bottom-line benefits of rooftop longevity is critical to specifying appropriate metal roofing solutions. The performance-to-cost ratio will vary with every roof specified, and can only be identified through a comprehensive review of several factors, including: • How long will the client own the property? Since metal roof systems can significantly outlast most non-metal alternatives, property owners who intend to hold on to their buildings longer will reap the largest rewards from metal's life cycle costing advantages. • How disruptive will eventual restoration and re-roofing be to the building's occupants? The installation of a metal roof is odour-free, cleaner, and more environmentally friendly than hot-applied systems. However, installing metal systems can present logistical concerns, especially for high-rise buildings with limited access. Although freight elevators can typically carry materials needed for non-metal systems, for metal systems, large cranes may be necessary to haul longer panels to the top of the building.
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• What is the intrinsic value of the property under the roof? The higher the value of the property occupying a building, the easier it is for building owners to rationalize the higher initial costs of metal systems. • What is the customer's existing budget? If price were no object, we'd all be living and working under roofs of copper, zinc, or even titanium. Regardless of the desirability of longterm solutions, short-term budget realities sometimes prohibit lasting solutions. When a customer's initial budget will not accommodate the costs of a premium metal, innovative financial products such as leasing may be considered. Equally relevant is how soon additional money will become available. It may make sense to install a lowcost alternative on new construction, when budgets are strained, if seven years down the road money will become available for installing a longer-lasting metal roof system. • How important are aesthetic considerations, given the roof 's location and the building's function? Aesthetic versatility is probably the single biggest reason that owners opt for metal roofing. When aesthetics are a major concern, metal roofing offers added value. • How likely is it that the owner will follow through on routine maintenance? Generally speaking, metal roofing requires less maintenance than non-metal systems, which may need more frequent recoating, fresh gravelling, or aggressive restoration to maintain resistance to ultraviolet (UV) radiation and weather. • How frequently will the roof need to be accessed due to HVAC, rooftop photovoltaic (PV) systems, or other utilities? Although metal systems withstand foot traffic as well or better than non-metal roofs, roofs that require a lot of penetrations for HVAC or other appliances are not ideal candidates for metal roofing. For more information, visit www.safintra.co.za.
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Know your insulation There are many types of insulation, derived from natural, mineral or petrochemical sources, as TIPSASA explains. It is important that the right insulation type be selected for the right application, and equally important that it gets installed correctly.
Photo credit: MealMakeoverMoms.
T
hermal insulation acts as an inhibitor to heat transfer – either by conduction, convection, radiation or a combination of these, reducing heat loss in winter to keep the building warm while reducing heat gain in summer to keep the building cool. Four categories of insulation products: 1. Bulk insulation – flexible (fibre) 2. Bulk insulation – rigid (cellular or fibre) 3. Reflective foil insulation (RFL, also known as ‘radiant barrier’) 4. Composite bulk insulation – flexible or rigid (cellular or fibre) Composite bulk insulation is a combination of numbers 1 or 2 and 3. While closed cell foam products have a greater R-value and provide stronger resistance against moisture and air leakage, the material is also much denser and more expensive to install than reflective foil and fibrous bulk insulation, which are less expensive.
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BULK INSULATION These are materials of low thermal conductivity that mainly resist (slow down) the transfer of conducted and convected heat, relying on pockets of trapped air or low conductive gases within their structure. The thermal resistance of bulk insulation is essentially the same regardless of the direction of heat flow through it, and is proportional to its thickness, density, and upper temperature.
WARNING: FIRE TESTING Insulation, composite insulation products and composite panels shall be tested with the maximum core or insulation thickness as stated in SANS204. DO NOT use insulation products in conjunction with other insulation types for ‘cheaper options’ in order to comply with SANS10400-XA Energy Usage In Buildings, unless it was tested to be used as such.
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I N S U L ATI O N
EXAMPLES OF FLEXIBLE BULK INSULATION Glass Wool (Fibreglass)
• Manufactured from molten glass that is spun and formed into mats, rolls and blankets, or fine fibres coated with a binding resin. Batts and blankets are lightweight, fit standard tie beams and stud spaces, and are easy to cut and install. • Should not be compressed or moistened. • Butt all ends and edges together firmly. If installed carefully, it will not slump or settle. • During installation the glass fibre can cause eye, skin and respiratory irritation – therefore the manufacturer’s safety recommendations must be followed. • Limited operating temperatures are at 350°C. • (Glass wool/Fibreglass can also be rigid bulk insulation.)
Mineral Wool (Slag/Rock Wool)
• Mineral wool is manufactured from molten industrial slag, which is fiberized and treated with oil and binders to suppress dust and maintain shape. It is similar to glass fibre in texture and appearance but denser than glass wool, therefore its R-value per unit thickness is higher. • Rock wool is manufactured in a similar manner, except that natural rock is used instead of slag. • It can cause eye, skin and respiratory irritation during installation – therefore the manufacturer’s safety recommendations must be followed. • These materials have a high fire resistance, limiting operating temperature at 850°C.
Polyester Fibre
• Made from polyester fibres (including recycled PET bottles) spun into a flexible mat. Available as batts or blankets. • Easy to cut and install. • Non-irritable, with no known physical or health hazards. • When exposed to a direct flame, the product will melt and shrink away from the flame. Limited operating temperature is 150°C.
Cellulose Fibre
• Made from finely shredded recycled paper that is milled into a light fibrous matrix and then chemically treated to resist fire and fungal growth. • Due to the small size of the particles, cellulose can ‘flow’ around obstructions (nails, electrical wires, trusses, etc.) to give a uniform fill. • If the insulation is not blown to the manufacturer’s recommended density and thickness it can settle over time, and the intended R-value will not be achieved and maintained.
EXAMPLES OF RIGID BULK INSULATION Expanded Polystyrene (EPS)
• A lightweight, plastic foam insulation that gets produced by trapping small amounts of pentane gas into solid beads of polystyrene. The pentane gas expands under the action of heat, applied as steam, to form perfectly closed cells of EPS. • These cells occupy approximately 40 times the volume of the original polystyrene bead. The EPS beads are then moulded into blocks or boards in three standard densities; low, medium and high. • EPS has excellent thermal properties, is moisture resistant, and provides environmentally safe, lifetime durability. • EPS is easy to install, non-toxic, contains no CFCs or HCFCs, and is recyclable.
Extruded Polystyrene (XPS)
• A closed cell polystyrene foam board that retains gas but excludes water. • It is produced on a continuous, fully automated extrusion process. It is manufactured in two densities; medium and high. • Most commonly used for slab-edge and cavity brick wall insulation. The high-density board should be used where the material will be exposed to relatively high pressures, such as below a concrete slab or in built-up roofing. • Polystyrene will ‘break down’ if left exposed to sunlight for prolonged periods, and must also be protected from solvents and non-compatible adhesives.
Polyurethane and Polyisocyanurate
• These insulations are manufactured by chemical reactions between poly-alcohols and isocyanurates creating or forming tiny air cells. The cells contain refrigerant gases (fluorocarbons) instead of air. • The boards are usually double-faced with foil, or sometimes come bonded with an interior or exterior finishing material. • The boards must be protected from prolonged exposure to water and sunlight. If used on the interior, it must be covered with a fire-resistant material such as drywall. • Due to the relatively high cost of these insulations, use is generally limited to areas that require a high R-value but where space is very limited.
Phenolic Foam
• Manufactured from phenol formaldehyde resin, and is available as either an open or closed cell product. • The boards usually come with a foil facing on one or both sides. • Much less combustible than other rigid insulations. • Should be protected from prolonged exposure to sunlight and water. • Suitable for wall sheathing, and for use on the interior – both above and below grade. • Use is generally limited to areas that require a high R-value but where space is very limited.
Polyurethane Foam
• Closed cell foam, usually pale-yellow in colour. • Can be used for a variety of spray applications. The material is mixed on site with special equipment for large applications. For small applications, single-component foam is available in spray cans for sealing around windows, doors, etc. • The foam will act as an air barrier but not a vapour barrier, and should be protected from prolonged exposure to sunlight. • When the foam is used in the interior of a house, it must be covered with a fire-resistant material such as drywall.
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Photo credit: Ryo Chijiiwa.
REFLECTIVE FOIL INSULATION
COMPOSITE BULK INSULATION
Reflective foil insulation (radiant barrier) mainly resists radiant heat flow due to its reflectivity, low absorption, conductivity and low emissivity (ability to re-radiate heat).
Composite bulk and reflective materials that combine some features of both types are available; for example, foil bonded to bulk insulation – whether blankets, batts or boards. (That is to say, foil faced blankets, foil faced batts, and foil faced boards.)
Reflective insulation works by letting through a small percentage of the radiant heat it receives and absorbs, and then reflecting a percentage of the rest using a shiny surface. An air gap next to the reflective surface creates a layer of air, which is important for reducing absorption and lowering the emittance to the opposite side from the direction of the heat source, thereby reducing heat flow through the system. Reflective insulation is more effective at reducing summer heat gain than slowing heat losses in winter, and this should be taken into account at thermal design stage. It relies on the presence of a defined air space next to the shiny surface. The thermal resistance of reflective insulation varies with the direction of heat flow through it, i.e. vertical, horizontal or at a degree angle. • Reflective foil is especially valuable in combination with bulk insulation for maximum performance. • It is a useful barrier against transfer of moisture. • Reflective surfaces need to remain clean and dust free. Dust build-up reduces the R-value of the product. NOTE: Reflective foil insulation should not be placed on top of ceilings or ceiling joists, nor under floors, as it is electrically conductive. Any such insulation must also be secured with non-conductive staples.
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Photo credit: Martin Pettitt.
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Photo credit: Mark Taylor.
INSULATION AND FIRE SAFETY SANS10400-T, Fire Safety, stipulates that when any insulation, roof lining or waterproof membrane not used as a ceiling and used under a roof covering as part of a roof assembly, is tested in accordance with SANS10177-5 and found to be combustible, such material shall be acceptable should it be classified, marked and installed in accordance with the requirements of SANS428.
SANS428 SANS428, the fire performance classification of thermal insulated building envelope systems, was developed to determine comparative burning behaviour and predict the potential for a self-propagating fire spread in a building fire environment, by measuring the maximum flame spread when exposed to a test fire. This Standard incorporates all factors required for fire-hazard or fire-risk assessment of the materials, products or assemblies under actual fire conditions. Standard testing procedures for thermal insulation to measure:
• Designated use and application: SANS10177-11, Fire testing of materials, components and elements used in buildings; Part 11: Large-scale fire performance evaluation of building envelope thermal insulation systems (with or without sprinklers). NOTE: The fire performance rating classification must be printed on all insulation products and/or packaging and data sheets. For example: A/A1 or B/B1/2/H or V. More information on insulation products classified in accordance with SANS428 is available on the TIPSASA website, in the TIPSASA Fire Database Register.
SOURCE CREDIT ‘TiPS Guidebook on Thermal Insulation & Energy Saving’ Copyright © TIPSASA 2016. TIPSASA is the Thermal Insulation Products & Systems Association SA. For more information, visit the TIPSASA website at www.tipsasa.co.za.
• Combustibility: SANS10177-5, Fire testing of materials, components and elements used in buildings; Part 5: Noncombustibility at 750°C of building materials. • Surface fire properties: SANS10177-10, Fire testing of materials, components and elements used in buildings; Part 10: Surface burning characteristics of building materials using the inverted channel tunnel test.
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C A S E S T U DY
Installation difficulties with complex residential roofs – gleanings from a case study Every so often, a timber roof truss manufacturer may be presented with a design and estimation request for an unusually complex residential roof—not necessarily one of such grand scale and proportion that it attracts the attention of a host of industry professionals, but rather one of average scale and with relatively small truss spans that is nevertheless very intricate. These fairly small but complicated projects can cause a lot of frustration for everyone involved. From client to architect, designer, manufacturer, installer and inspector – time and costs can quickly mount up. The following reflects on one such case. Article by Stian de Jager: Engineer, ITC-SA Roof Inspector (Category A - COC/0303/INS), and Founder of De Jager Roofs Business Trust “This article is a case study of a project in Kensington, Johannesburg, where I was involved as roof inspector, and the lessons learned from it.
Above and below: Truss hangers not installed as a result of confusion with a different section and detail.
The roof structure of this new residence was designed to carry concrete roof tiles. The roof area measures a little over 300m2 – nothing out of the ordinary. That is, until taking into account the walls that were designed and built just slightly out of square (less than 5 degrees), while the roof was specified to be square. In addition, the building has a cranked section at 40 degrees – which further complicated the design and measuring of the site. The result was a roof design with more than 100 different truss labels, enough to startle even some of the most competent roof installers.
MULTIPLE REASONS FOR PROBLEMS A prominent finding gleaned from this study was that the eventual installation difficulties and issues experienced on site could not be ascribed to a single source. Often, in my experience, problems arise as a result of a combination of factors, starting with uninformed clients and inexperienced or easily conceding architects (especially when dealing with wilful clients). And when you add designers working under pressure as well as installers who do not communicate effectively, it becomes clear how the on-site installation can spiral out of control.
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CASE STUDY
In such difficult situations, installers can easily get overwhelmed by the sheer complexity of the design. It is then that even experienced installers tend to start making novice mistakes. Planning and good communication go out the window and a ‘let’s just make the trusses fit’ attitude is usually adopted. The unfortunate but typical disconnect between designer, installer and inspector also contributes massively to the problem. In these complex cases, even though relatively small in scale, there should be much less separation of concern amongst the parties involved. This can quite easily be overcome, as indicated in the ‘solution’ section of this article. Insufficient details passed from the architect to the roof designer can also lead to assumptions being made, which could later become disputes after the trusses have already been manufactured. And yet another contributing factor can be a lack of special installation details from the manufacturer’s designer to accompany the drawings that are sent to site for the installer.
On-site modification without prior consent and detailed instructions from designer.
SOME SPECIFICS First is the very common misapplication of the universal nailing details as specified by the various systems for roof truss manufacturing in Southern Africa. This is often applied incorrectly at the perpendicular connections of jack trusses to girders at open hips or 90-degree infill hips. Next is the inadequate or incorrect nailing of truss hangers, bracing, truss and batten connections. Because of the overwhelming complexity, confusion with regard to bracing items, cleats, hangers and other details can occur – with many switched around and some even left out completely. In the same way, several of the small trusses can be neglected because the main trusses are repeatedly repositioned in an attempt to ‘make the roof fit.’ These are then left out of the structure, causing some unstructured open spaces in the roof. This then leaves the adjacent trusses to carry an additional load they were not designed to bear.
A 45-degree truss hanger not installed, and a 90-degree hanger not fully nailed.
Another major issue that can arise is the on-site modification and cutting of trusses by installers without the prior consent and instruction detail from the designers. Not only does this compromise the integrity of the roof structure, it is also not necessary in most cases (the trusses might merely need to be positioned correctly). Finally, many support blocks on internal walls that were meant to be temporary to aid in the positioning, can be forgotten and left in place. If this is not picked up by an inspector prior to roof loading, severe bending moments around these points can be created, for which the trusses were not designed, and they can fail at these or other points. Even though this list is quite extensive already, it only highlights the most prominent issues discovered during this case study.
Truss hangers not fully nailed.
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Damaged nail plate and twisted end-vertical.
Universal nailing inadequately applied.
IMPACTING EFFECTS AND RESULTS In this specific case, fortunately, the installation issues were on a new residence and I was called out to inspect the structure timeously. But regardless, when taking the cost of capital at interest and other consequential costs into account, it is clear that all the delays caused by installation difficulties can be very detrimental. Sometimes installers will start loading the roof tiles before the structure has been inspected, and this can have some damaging results. In complex roofs where bracing and metalwork can easily be installed in the wrong positions or neglected, long compression truss members can buckle and tension members can pull out of nail plates.
THE SOLUTION Ideally, clients, architects and roof designers should meet during the planning stage of the project for discussion on any complex and ‘out of the ordinary’ roofs caused by walls that are not perpendicular, and the like. This is not always possible, and quite often the walls are already started by the time the truss manufacturer receives the drawings to do an estimation for the roof. When such a meeting is not possible, it can be of great benefit to all parties to get a competent roof inspector involved right at the start of the roof installation. Depending on the complexity and scale of the project, the roof inspector would visit the site at least daily. This is to ensure that mistakes are not compounded and that the communication between installer and designer is clear. The inspector or engineer who will sign off the roof, can also see and request the necessary special details from designers to installers in a timely manner. These simple steps can greatly reduce the time spent on site and ensure an accurate and efficient installation process.” For more information, contact the author, Stian de Jager, via email to djroofs@gmail.com, or visit www.djroofs.co.za.
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2015/08/20 5:04 PM
August is Women’s Month, and a great opportunity to put the spotlight on women in construction. Meet Elrene Smuts, the professional behind communications at a.b.e. Construction Chemicals (Pty.) Ltd., part of the Chryso Southern Africa Group.
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lrene explains that, five years after starting with a.b.e. as a sales representative, her potential, backed by a degree in marketing, was fully recognized when the company created a marketing department and she was promoted to Brand Manager. “That was 10 years ago, and with the experience and knowledge of our company and its products I’ve gained since then, I now hold the position of Communications Manager – reporting to the Chief Operating Officer,” Elrene says.
Elrene Smuts, Communications Manager at a.b.e. Construction Chemicals.
“I am responsible for the department’s performance and success in reaching company objectives by staying focused on various yearly, monthly and day-to-day marketing and sales focus areas,” Elrene continues. Her responsibilities include: Developing strategies that optimize the brand, coordinating customer activities, managing new product launches, creating and maintaining literature, and implementing promotional campaigns.
One of a.b.e.’s main product segments is waterproofing, which the company started in 1932 by supplying bitumen to the municipalities in KwaZulu-Natal. Over the last 80 years the company has presented their construction, export and retail market channels with highquality and innovative waterproofing product systems. “It is a challenge to maintain our market leadership in this very competitive product market,” Elrene remarks. “Being a woman has its advantages and disadvantages, but I believe that knowledge is power. If you are confident, enthusiastic and dynamic, you can cope with any circumstances,” Elrene asserts. She has some inspiring words for other aspiring women who may find themselves in a male-dominated industry: “Look for those important opportunities in life, be patient, stay professional at all times, and grow with your strengths.”
WOMEN IN CONSTRUCTION
Knowledge is power
BRICK ROOF FEATURE
Brick-topia The Brick-topia project by Map13 Barcelona, a most innovative architectural expression that resulted in this unusual brick roof structure, has been awarded with the WAN Small Spaces Award 2015 in the subcategory Temporary. Photo credit: Manuel de Lózar y Paula López Barba, courtesy of v2com
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ith this project, Map13 Barcelona presents its fresh and striking architecture based on meticulous research that explored the limits of material and structure. Brick-topia has been declared the winning project of a competition to build a pavilion at the International Festival of Architecture Eme3, in Barcelona. It is an unreinforced masonry shell made of brick, using a traditional construction technique called ‘tile vault.’ The scheme was the result of a combination of the latest structural analysis and form-finding computational tools with a traditional, sustainable, inexpensive and effective construction technique.
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B R I C K ROO F F E AT U R E The shape of the pavilion is the outcome of a thorough design process optimizing the structure through geometry using the software RhinoVault. The unreinforced masonry shell showed a complex geometry with a thickness ranging from 65mm to 118mm, and it was designed to present challenging features in terms of structure and construction. The strict constraints on budget and time also required innovation during the construction process. The pavilion was built in only three weeks, and within that timeframe, a new falsework system was developed using scaffolding, cardboard, wire, and steel rods. The system allowed for a quick, economic and low-tech construction available in almost any kind of context. For more information, visit www.map13bcn.com.
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INDUSTRY NEWS
New welding technology for thick insulation boards An innovative technology, although not yet introduced in South Africa, is making combinations of different insulation materials possible – with clear benefits for the global construction industry.
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ASF (Germany) has worked with a well known machine manufacturer to develop a new technology for welding insulation boards. The contactless, thermal welding process makes it possible to combine a variety of insulation materials. For example, Styrodur ®, the extruded rigid polystyrene foam from BASF, can be combined with polyurethane, inorganic insulation materials, or the melamine resin foam Basotect ® to form completely new insulation material solutions. The Styrodur portfolio also includes new, especially thick boards that are made using this process, in the highly compressionproof varieties Styrodur 4000 CS and 5000 CS. The boards cover the thickness range from 60mm to 240mm with a consistently good insulation value (lambda: 0.035 W/(m•K)).
ADVANTAGES FOR THE CONSTRUCTION INDUSTRY Architects, planners and craftsmen can benefit from the new possibilities: The traditional advantages of the Styrodur board, such as low water absorption and high compressive strength, can be combined with the desirable properties of other building products.
BASF has already patented a range of applications and product combinations. On this basis, the company is seeking to develop and advance new applications in building insulation together with interested partners.
ABOUT STYRODUR® The compression-proof, water-repellent and rot-proof Styrodur ® has protected homes from heat, cold, and moisture for more than 50 years. The green XPS is characterized by its reliable product quality as well as the continuous efforts to gain approvals. Today, Styrodur is the insulation material with the greatest number of officially approved uses in the German XPS market. Insulation with Styrodur prolongs the lifespan of buildings, increases their value, and improves the living environment. The various Styrodur types, which contain air as the cell gas, differ mainly in their compressive strength.
For more information, visit www.styrodur.com.
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Importer & Distributor for Southern Africa Faitsch Products • 20 van der Berg Crescent • Gants Centre • Strand Tel: 086 000 4126 • Fax: 086 567 1100 E-mail: info@faitsch-products.com • www.faitsch-products.com
Built over years, perfected with time. JCP Roofing is a family business that came into existence through JCP STEEL, a company that has been serving the steel industry with flat steel products for over 22 years, with a reputation for excellent service, uncompromising quality and impressive lead times. Expanding our portfolio to supply IBR and corrugated roofing sheets to the same level of service our customers grew accustomed to over the years, has been our vision and dream. Take the time to call us on 011 814 1898 and we will help you perfect your project Products: IBR • Corrugated • Polycarbonate Sheeting • Bullnosing/Cranking • Flat Sheets • Screws & Fasteners Tel: +27 11 814 1898 | Fax: +27 11 814 2166 Email: info@jcproofing.co.za | Web: www.jcproofing.co.za