1 08 sect1 9

AS 1684 2006 Editions Part 1 Design criteria

Part 2 Part 3 Residential timber-framed construction

Part 4

1

SECTION 1 SCOPE AND GENERAL

1.4 Â LIMITATIONS Generally the limitations given in AS 1684 apply because of the limits of the design information given in AS 1684. e.g. - the bracing tables given in the standard are limited to a 16 m wide building and 35O roof pitch.

2

Building Classes Class 1(a)

- Detached house Attached dwellings (Terrace houses, Villas etc.)

Class 1(b)

- Boarding house • not more than 300 sq. mtrs • not more than 12 residents

Class 10

- Outbuildings (garages, carports etc.)

Class 2

- Building containing 2 or more sole occupancy units.

3

Multi Residential Timber Framed Construction

4

Conventional Frame T im b e r o r m e ta l b r a c in g

T o p p la te L in t e l S h e e t b ra c in g

C o m m o n s tu d N o g g in g L in t e l tr im m e r B o t to m p la t e

W a ll in te r s e c t io n

J a m b s tu d J a c k s tu d s S i ll tr im m e r

5

1.4.2 Wind Classification TABLE 1.1

Non-cyclonic

MAXIMUM DESIGN GUST WIND SPEED Maximum design gust wind speed (m/s)

Wind classification regions A and B

Permissible stress method (V p )

Serviceability limit state (V s )

Ultimate limit state (V u)

N1

28 (W28N)

26

34

N2

33 (W33N)

26

40

N3

41 (W41N)

32

50

N4

50 (W50N)

39

61

6

W 1 6 .0 m m a x .

W 1 6 .0 m m a x .

1.4.3 The building shown opposite is Plan

considered to be ‘two storeys of timber framing’.

See comments Section 2 - Clause 2.7.8 for more information.

7

1.6.6 Wall height The maximum wall

height shall be 3000Â mm (floor to ceiling) as measured at common external walls, i.e. not gable or skillion ends. (see Figure 1.1)

1.6.7 Roof The maximum roof pitch shall be 35° Pitch (70:100).

8

F o r th e d e s ig n o f th e RAFTER r o o f m a s s w ill b e : -

1.4.9 Roof types Appendix B 1.4.10 Building Page 219 R id g e b o a r d Masses

w e ig h t o f r o o fin g m a te r ia l + w e ig h t o f r o o f b a t te n s + s a r k in g & in s u la tio n

C o lla r t ie R o o f B a tte n

STRUTS S h e e t o r T ile ro o f

F o r th e d e s ig n o f th e U N D E R P U R L IN , r o o f m a s s w ill b e : _ w e ig h t o f r o o fin g m a te r ia l + w e ig h t o f r o o f b a t te n s + s a r k in g & in s u la tio n (T h e w e ig h t o f r a f te r s is a c c o u n t e d f o r in t h e d e s ig n )

S T R U T T IN G B E A M S , S T R U T T IN G / H A N G IN G B E A M S r o o f m a s s w ill b e a c h o ic e o f S h e e t o r T ile R o o f A 1 2 k g /m 2 c e ilin g m a s s h a s b e e n a llo w e d f o r in t h e d e s ig n o f C E IL IN G J O IS T & H A N G IN G B E A M S

9

1.6 FORCES ON BUILDINGS S u c tio n ( u p lif t ) C o n s t r u c tio n lo a d s ( p e o p le , m a te r ia ls )

D E A D L O A D (s tr u c tu re )

L IV E L O A D S (p e o p le , fu rn itu re e tc .)

W in d

In te rn a l p re s s u re

S u c tio n D E A D L O A D (s tru c tu re )

(a) Gravity loads

(b) Uplift wind loads

NOTE: For clarity, earthquake and snow loads are not shown (see Clause 1.7 ).

FIGURE 1.2 LOADS ON BUILDINGS Back to slide 155

10

Racking (wall deformation)

O v e r t u r n in g ( r o ta t io n )

S lid in g ( t e n d e n c y t o s lid e )

Back 155

Back 161

U p lift ( c o n n e c t io n f a ilu r e )

11

TABLE 1.2 STRESS GRADES Most common stress grades available

Other stress grades available

F5

F7

F8, F11, F14

F17

Hardwood (seasoned)

F17

F22*, F27

Hardwood (seasoned Western Australia)

F14

ď‚ž

Seasoned softwood (radiata, slash, hoop, Carribean, pinaster pines etc.)

F5, F7, F8, MGP10, MGP12

F4*, F11*, MGP15

F5, F7

F8*, F11*

Spruce pine fir (SPF) (seasoned)

F5

F8

Hemfir (seasoned)

F5

F8

Species or species group Cypress (unseasoned) Hardwood (unseasoned)

Douglas fir (Oregon) (unseasoned)

*

Span Tables in the Supplements for these grades and species are not available.

NOTES: 1

Timber that has been visually, mechanically or proof stress graded may be used in accordance with this Standard at the stress grade branded thereon.

2

Check local timber suppliers regarding availability of timber stress grades.

12

Page 17

TABLE 1.3 ALTERNATIVE TIMBER DIMENSIONS Minimum seasoned timber dimension (mm)

Nominal unseasoned timber dimensions

Minimum seasoned W.A. hardwood dimensions

19

25

19

32

38

30

35

38

30

42

50

40

45

50

40

70

75

60

90

100

80

120

125

125

140

150

125

170

175

175

190

200

175

240

250

220

290

300

260

13

SECTION 2 TERMINOLOGY AND DEFINITIONS 2.1 GENERAL

The terminology and definitions given in this Section shall be used in conjunction with the requirements of this Standard.

The terminology used by the building industry varies greatly between states, regions within states and even between those working in the same region. Where possible, the more commonly used terms have been adopted by this standard.

14

Hanging beam Cleat (hanger) Rafter Fascia Soffit bearer Lintel Ledger Jack stud Sill trimmer

Jamb stud

Ceiling joist Jack ceiling joist (trimmer) Top wall plate Brace Nogging Common stud Bottom wall plate

Jack stud Floor joist Bearer

Termite shield (ant cap)

Stump (post, pier)

FIGURE 2.1 FRAMING MEMBERS — FLOOR, WALL AND CEILING 15

2.3 VERTICAL NAIL

LAMINATION 2.4 STUD LAMINATION

2.5 HORIZONTAL NAIL

LAMINATION WALL PLATES ONLY 2.6 LOAD WIDTH AND AREA SUPPORTED

16

FIGURE 2.11 FLOOR LOAD WIDTH (FLW) TWO STOREY CONSTRUCTION

Bearers supporting lower storey loadbearing w RLW

Total Load A add RLW

FLW bearer A = Upper FLW Lower FLW

x a 2 x 2

FLW F LW

F LW D

FLW

B

A a

C

F LW

F LW

x

D

y

F LW

z 17

FIGURE 2.11 FLOOR LOAD WIDTH (FLW)  TWO STOREY CONSTRUCTION con’t Bearers supporting lower storey loadbearing w

FLW bearer B = Upper FLW

+ Lower FLW

x y 2 x y 2

FLW F LW

F LW D

FLW

A

a

C

B

F LW

x

D

F LW

y

F LW

z 18

FIGURE 2.12 CEILING LOAD WIDTH (CLW)

x 2

CLW Hanging beam D =

D

E

C LW

C LW

x A

y

B

C 19

2.6.4 Roof load width (RLW) The(cont’d) same applies to pitched roofs, however the loads are spread between more support points - walls A, B, the underpurlins and ridge struts (if used).

1

A

2 3

B

Although RLW's are not shown in AS1684 for the underpurlins, an equivalent measurement to these RLW's will be required to calculate the area supported for the studs that will support the concentrated loads at the end of struts and/or strutting beams that support the underpurlins.

20

FIGURE 2.13 ROOF LOAD WIDTH (RLW)

(b) Cathedral roof.

R LW + R LW

x

y

a

b

A

x y RLW wall C = 2

C

x a RLW wall A = 2

B

y b RLW wall B = 2 21

2.7.4 Roofs 2.7.4.1 Coupled roof R id g e b o a rd

R a fte r C e ilin g jo is t

R a ft e r s & C e i lin g J o is t m u s t b e f ix e d t o g e t h e r a t t h e p it c h in g p o in t s

o th e r w is e th e r e is n o th in g to s t o p th e w a lls fr o m s p r e a d in g a n d th e r o o f fr o m c o lla p s in g

R id g e b o a r d

R a fte r

C e ilin g j o is t ( C o lla r T ie ) T h is m e th o d o f r o o f c o n s tr u c tio n is n o t c o v e r e d b y A S 1 6 8 4

22

2.7.4.2 Non-coupled roof A pitched roof that is not a coupled roof and includes cathedral roofs and roofs constructed using ridge and intermediate beams.

A non-coupled roof relies on ridge and intermediate beams to support the centre of the roof. These ridge and intermediate beams are supported by walls and/or posts at either end.

R id g e B e a m

R a fte r

In t e r m e d ia t e B e a m

23

2.7.5 Span and spacing 2.7.5.1 General

Figure 2.18 illustrates the terms for spacing, span, and single and continuous span.

2.7.5.2 Spacing

The centre-to-centre distance between structural members, unless otherwise indicated.

2.7.5.3 Span The face-to-face distance between points capable of giving full support to structural members or assemblies. In particular, rafter spans are measured as the distance between points of support along the length of the rafter and not as the horizontal projection of this distance.

24

2.7.5.4 Single Span The span of a member supported at or near both ends with no immediate supports. This includes the case where members are partially cut through over intermediate supports to remove spring (see Figures 2.18(c) and 2.18(d)).

S in g le s p a n

(c) Two supports

Saw cut

J o in t o r la p

S in g le s p a n

S in g le s p a n

(d) Joint or sawcut over supports

FIGURE 2.18 SPACING AND SPAN back to previous

25

2.7.5.5 Continuous Span The term applied to members supported at or near both ends and at one or more intermediate points such that no span is greater than twice another (see Figure 2.18(e)).

C o n t in u o u s sp a n

C o n tin u o u s sp a n

NOTE: The design span is the average span unless one span is more than 10% longer than another, in which case the design span is the longest span.

(e) Continuous span FIGURE 2.18 SPACING AND SPAN 26

SPACING AND SPAN (a) Bearers and joists

late u c cal

af t R d

an p s er

FIGURE 2.18 SPACING AND SPAN (b) Rafter

27

2.7.6 Stress grade 2.7.7 Stud height

AS1684



AS1684



2.7.8

Two Storey

Requires engineering advice

End of Section 2

28

SECTION 3 SUBSTRUCTURE

29

3.1 SCOPE 3.2 SITE PREPARATION AND DRAINAGE 3.2.2 Site clearing 3.2.3 Site drainage

3.3 GROUND CLEARANCE & SUBFLOOR VENTILATION 3.4 DURABILITY 3.4.1 Termite management

3.4.2 Species selection 3.5 SUBSTRUCTURE BRACING 3.6 SUB-FLOOR SUPPORTS 3.6.1 General 3.6.2 Soil classification 3.6.3 Procedure 3.6.4 Determination of vertical gravity loads 3.6.4.1 General 3.6.4.2 Permanent (dead) loads (G) 3.6.4.3 Live loads (Q) 3.6.5 DETERMINATION OF VERTICAL GRAVITY LOADS 30

EXAMPLE – LOAD CALCULATION : Calculate floor areas supported by each post as per 2.6.5 Area supported.

B e a re r span 3000

½ + ½

½

+ ½

A

D

B

E

½ ½

F lo o r jo is t span 3600

F lo o r jo is t span 3600

½

B e a re r span 3000

C

F

½

B e a re r span 3000

+ ½

½

Area supported by post at A = 1.5m x 1.8m = 2.7m² B = 1.5m x 3.6m = 5.4m² D = 3.0m x 1.8m = 5.4m² E = 3.0m x 3.6m = 10.8m² A= C D=F 31

EXAMPLE FLOOR LOADS : Assuming a timber floor with light weight covering - 0.3 kN/m² WALL LOADS : Using the areas supported the wall loads on the posts is – 0.4 kN/m2 NOTE: The value of 0.4 kN/m² applied to the floor area has been determined as a typical distributed wall load averaged over the floor area for most housing.

Dead Load (combined load for floor + wall) A = 2.7 x (0.3 + 0.4) = 1.89 kN B = 5.4 x (0.3 + 0.4) = 3.78 kN D = 5.4 x (0.3 + 0.4) = 3.78 kN E = 10.8 x (0.3 + 0.4) = 7.56 kN Live Load (load for floor) A = 2.7 x (1.5) = 4.05 kN B = 5.4 x (1.5) = 8.10 kN D = 5.4 x (1.5) = 8.10 kN E = 10.8 x (1.5) = 16.2 kN

Dead + Live Load A= B= D= E=

1.86 + 4.05 kN = 5.91 kN 3.78 + 8.10 kN = 11.88 kN 3.78 + 8.10 kN = 11.88 kN 10.80 + 16.2 kN = 27.00 kN

Example P = G + 0.5 Q Total Load on Stump E = 7.56 + 0.5 x 27 =21.06 kN

32

Pitched Roof - assuming no point loads from strutting beams etc. and that roof loads on wall X will be taken by post at B and roof loads on wall Y will be evenly distributed between posts at B and C ..............

B e a re r span 3000

600 m m o v e rh a n g

X

A

Y

B

C

+ ½

R LW

O

A

D

B

E

C

F

R LW

20

½

R LW

½

B e a re r span 3000

33

3.6.6 Footing size or bearing area The size of footing may be determined directly from Table 3.2 for the total vertical bearing load, P (kN), determined from Clause 3.6.5. Alternatively, the bearing area required for the footing, A (m2), may be determined as follows:

A =

P/100

NOTES: 1

The 100 kPa is the allowable bearing capacity of

2

For worked examples, see Appendix E.

the foundation.

TABLE 3.2 BEARING LOAD AND FOOTING SIZE Total vertical bearing load (kN)

Minimum concrete pier or stump or sole plate diameter (mm)

Minimum concrete pier/stump or sole plate size (mm  mm)

4.9

250

225  225

7.1

300

275  275

9.0

350

300  300

12

400

350  350

16

450

400  400

34

3.7.3 Stumps and posts 3.7.4 Footing type support limitations (load widths × bearer spans) TABLE 3.5 LOAD WIDTHS AND BEARER SPANS FOR FOOTING TYPES 1 TO 5 FOR BEARERS SUPPORTING FLOOR LOADS ONLY Floor load width (mm) Footing type

1200

1500

1800

2100

2400

3000

3600

Maximum permissible bearer span (mm) 1

2 400

1 900

1 600

1 400

1 200

1 000

800

2

4 800

3 900

3 200

2 800

2 400

1 900

1 600

3

6 400

5 200

4 300

3 700

3 200

2 600

2 100

4

9 700

7 700

6 400

5 500

4 800

3 900

3 200

5

12 100

9 700

8 100

6 900

6 000

4 800

4 000

NOTES: 1

Maximum permissible bearer span is for each footing type. Bearer size is determined from the relevant Span Tables in the Supplements (see Section 4).

2

The Table values are based on a distributed load of 1.55 kPa being 0.4 kPa wall load spread over the floor area, 0.4 kPa floor load and 0.75 kPa permanent live load.

End of Section 3

35

SECTION 4 FLOOR FRAMING

36

4.1 GENERAL 4.1.1 Scope 4.1.2 Materials 4.1.3 Framing configurations 4.1.4 Weatherproofing 4.1.5 Shrinkage 4.2 BUILDING PRACTICE 4.2.1 Bearers 4.2.2 Floor joists

37

Appendix F F3 ALLOWANCE FOR SHRINKAGE

T im b e r fra m e

C le a ra n c e b e tw e e n lin te l a n d r e v e a l lin in g

C le a ra n c e B r ic k w o r k

( a ) B r ic k v e n e e r t o b e k e p t c le a r o f u n s e a s o n e d f r a m in g

( b ) C le a r a n c e a t d o o r a n d w in d o w h e a d s

C le a t

M in . D /1 0 D

S easoned beam

U nseasoned p u r lin s

( e ) A ll o w a n c e f o r d if f e r e n t s h r in k a g e o f u n s e a s o n e d a n d s e a s o n e d m e m b e rs

G a p = D /1 0 m in .

D

U nseasoned f lo o r jo is ts

S te e l b e a re rs

( f ) A ll o w a n c e f o r s h r i n k a g e o f u n s e a s o n e d t im b e r in c o m b in e d s t e e l a n d t im b e r c o n s t r u c t io n

38

4.2.2 Joists 4.2.2.1 General Joists shall be laid with their top surfaces level to receive flooring.

Spacing of joists shall be determined by the span capacity of the flooring (see Section 5).

(b) Platform flooring

(a) Fitted flooring 1 2 m m m in . b e a r in g

1 2 m m m in . b e a r in g

39

back 47

4.2.2.3 Deep joists L a te ra l L o a d d u e to W in d o r

U n d e r la te ra l w in d o r e a rth q u a k e lo a d , d e e p J o is t m a y t e n d t o r o ll o v e r if n o t b lo c k e d @ 1 8 0 0 c rs . m a x . o v e r s u p p o rts .

R im b o a r d

18 00 m

ax 40

4.3 MEMBER SIZES 4.3.1 Bearers 4.3.1.1 Bearers supporting loadbearing walls 4.3.1.2 Bearers supporting floor loads only

4.3.2 Floor joists 4.3.2.3 Floor joists supporting loadbearing walls at right angles to joists 4.3.2.4 Single or upper storey floor joists supporting roof point loads and loadbearing walls parallel to joists

41

NOTE: Bearer tables are the same for all wind classifications

42

4.3.2 Floor Joist 4.3.2.1 General The size of floor joists shall be determined from Span Table 6 of the Supplements.

Floor bearer

Jo ist

Floor Joist

Sp an Jo ist

Sp an

FIGURE 4.9 FLOOR JOISTS (a) Design parameters

ist ing o J ac Sp

‘AS 1170.1 Dead and live loads and load combinations’, requires that the floor live loads for houses to be 1.5 kPa However ‘balconies’ (patios, verandahs etc.)

1000 mm or more above ground, are required to be 3.0 kPa.

43

NOTE: Floor Joist tables are the same for all wind classifications

44

m m 00 0 3

x. a m

Trimming Joist Metal connectors when span of trimmers exceeds 1000mm.

Trimmers Metal connectors when span of trimmed joist exceeds 1000mm.

FIGURE 4.10 OPENINGS IN FLOORS

Curtailed joists (trimmed joist)

End of Section 4

45

SECTION 5 FLOORING

46

5.1 SCOPE This Section specifies the requirements for the installation of tongued and grooved strip flooring as well as plywood and particleboard sheet flooring.

5.2 PLATFORM FLOORS 5.3 FITTED FLOORS (CUT-IN FLOORS) 5.4 EXPASIOM JOINTS 47

5.5 LAYING AND FIXING 5.5.1 Strip flooring 5.5.1.1 Laying

5.2 Cramping 5.5.2.2 Fixing General 5.5.2.3 Fixing to structural plywood underlay

5.5.3 Structural plywood flooring 5.5.3.1 Laying 5.5.3.2 Fixing

5.5.4 Particleboard 5.5.4.1 5.5.4.2 5.5.4.3

General Laying Fixing 48

3 0 0 m m c e n tre s a t in te r m e d ia t e jo is t s a n d n o g g in g s

B e a re r

S tu m p 1 0 m m fro m e d g e a t 1 5 0 m m c e n tre s a t e n d s a n d jo in ts

D ire c tio n o f fa c e g r a in o f p ly w o o d

FIGURE 5.5 FIXING OF PLYWOOD SHEET FLOORING

49

Page 56

End of Section 5 50

SECTION 6 WALL FRAMING 6.1 GENERAL 6.1.1 Scope This Section sets out the requirements for the construction of conventional stud-framed walls and shall be used in conjunction with Span Tables 7 to 20 (single or upper-storey construction), 36 to 48 (lowerstorey construction), or 51 to 53 (verandahs and posts) of the Supplements.

51

T im b e r o r m e ta l b r a c in g

T o p p la t e S he et b r a c in g

C om m on s tu d L in te l

N o g g in g

W a ll in te r s e c tio n

B o t to m p la te

J a c k s tu d J a m b s tu d

Figure 1.6 Wall Frame MEMBERS 52

6.2 BUILDING PRACTICE 6.2.1.2 Common studs 6.2.1.3 Wall junctions S tu d s to b e s e c u r e ly fix e d w ith b lo c k in g a n d n a ils

N o g g in g s a t m a x .

9 0 0 m m s p a c in g

P r o v id e m in im u m 2 0 0 m m lo n g s tu d s iz e b lo c k s s p a c e d m a x . 9 0 0 m m a p a rt

S t u d s t o b e s e c u r e ly fix e d w ith b lo c k in g a n d n a ils

S p e c ia l fix in g m a y b e r e q u ir e d fo r in te r n a l lin in g s

S u ita b le fo r e x te r n a l b r ic k v e n e e r w a lls

(a) Intersections

(b) Corners

FIGURE 6.3 TYPICAL WALL JUNCTIONS 53

Wall Studs

S tu d b r e a d th B

S tu d d e p th (D )

S tu d C E

A H A H P

E F

B o t t o m p la t e

6.2.1.5 Nogging

6.2.1.4 Notching

54

6.2.2 PLATES 6.2.2.1 General Top plates shall be provided along the full length of all walls including over openings.

6.2.2.2 Bottom plates Bottom plates shall be provided along the full length of all walls except at door openings.

6.2.2.3 Stiffening of top plates Where a concentration of load (from roof beams, struts, strutting beams, girder truss, hanging beams or counter beams 3000 mm or more in length, occurs between studs top plates shall be stiffened

C o n c e n tr a t io n o f lo a d In te r m e d ia te v e rtic a l b lo c k in g m in . s iz e a s fo r c o m m o n s tu d s .

T o p p la te

T w o n a ils a t e a c h j o in t

55

6 0650 0m m

6.2.3 Openings

L in te l J a m b s tu d L in t e l t r im m e r S e c o n d a r y ja m b s t u d

L i n t e l t r im m e r J a c k s tu d

If exceed 650 mm, the lintel trimmer must be designed as per sill trimmers

56

6.2.5 Lateral support for non- loadbearing walls 6.2.5.1 External walls External walls shall be laterally supported against wind forces.

External walls supporting ceiling joists, rafters or trusses are deemed to have adequate lateral support.

57

6.2.5.2 Internal walls (trussed roofs) Non-loadbearing walls shall be kept a minimum of 10 mm below the underside of the bottom chord, or ceiling battens when used.

Trusses shall be fixed to internal non-loadbearing walls as shown in Figure 6.11, or as required for bracing (see Clause 8.3.6.9).

T ru s s p a r a lle l to w a ll

F o b s

o r fix in g f in t e r n a l r a c in g w a lls , e e S e c t io n 8

W a ll t o p p la te

(a ) T ru s s p a ra lle l to w a ll

T ru s s a t rig h t a n g le to w a ll

S lo tte d b ra c k e t a t 1 8 0 0 m m c e n tr e s to a llo w v e rt ic a l m o v e m e n t o f tr u s s o n lo a d in g (b ) T ru ss p e rp e n d ic u la r to w all

FIGURE 6.11 FIXING OF TRUSSES TO A NON-LOADBEARING INTERNAL WALL 58

WALL FRAMING 6.3 MEMBER SIZES 6.3.1 General Clauses 6.3.2 to 6.3.7 provide details with respect to the determination of wall framing member sizes, which shall be determined from the appropriate Span Table given in the Supplements.

6.3.2 Wall studs 6.3.2.1 Common studs 6.3.2.2 Studs supporting concentrated loads 6.3.2.3 Jamb studs (studs at sides of openings) 6.3.2.4 Concentrated loads on non-loadbearing internal walls 6.3.3 Bottom plates 6.3.4 Top plates 6.3.5 Studs, plates and noggings in non-loadbearing internal walls 6.3.6 Lintels

59

(a) Single or upper storey loadbearing walls

(b) Lower storey loadbearing walls

FIGURE 6.12 COMMON WALL STUDS 60

2900 61

of n pa rlin S u A = derp )A 2 / Un (1

RIDGE STRUTTED B

/2 (1

)B

B = combined span of rafters either side of underpurlin Roof strut

Strutting Beam

Stud supporting concentrated load from strutting beam Roof area supported = (1/2)A × (1/2)B

FIGURE 6.13 STUDS SUPPORTING CONCENTRATIONS OF LOADING 62

RIDGE NOT STRUTTED )B /4 (3

of n pa rlin S u A = d e rp A ) n 2 U (1/

B = combined span of rafters either side of underpurlin Roof strut

Strutting Beam

Stud supporting concentrated load from strutting beam

Roof area supported = (1/2)A × (3/4)B FIGURE 6.13 STUDS SUPPORTING CONCENTRATIONS OF LOADING

63

A = Span of roof beam

A B

Stud supporting concentrated load from Roof Beam

B = combined span of rafters either side of roof beam

Roof area supported = (A × B)/4

FIGURE 6.13 STUDS SUPPORTING CONCENTRATIONS OF LOADING 64

90x35

7

65

Upper floor bearer A = Span of Upper floor bearer

B

A

Upper floor joist

Stud supporting concentrated load from upper floor bearer

B = combined span of floor joist either side bearer

Floor area supported = (A × B)/4

FIGURE 6.13 STUDS SUPPORTING CONCENTRATIONS OF LOADING

66

67

6.3.2.3 Jamb studsb (studs at sides of openings)

The size of jamb studs for single or upper storey construction shall be determined from Span Table 11 of the Supplements.

(a) Single or upper storey

FIGURE 6.14 JAMB STUDS

68

69

6.3.2.3 Jamb studs (studs at sides of openings) Example: It has been determined from Table 11 that 2/70x35 jamb studs are required.

Extra stud under lintel to carry concentrated load

To carry the concentrated load, it is determined from Table 9 that 2/70 x 35 studs are required.

Because the concentrated load is within the middle 1/3, 1/70x35 is placed either side and under the lintel.

70

The size of bottom plates in single or upper-storey construction shall be determined from Span Table 14 of the Supplements The size of bottom plates in the lowerstorey of two-storey construction shall be determined from Span Table 45 of the Supplements.

(b) Lower storey

(a) Single or upper storey

6.3.3 Bottom plates FIGURE 6.18 BOTTOM PLATES 71

72

6.3.4 Top plates The size of top plates for the single storey or the upper storey of a two-storey construction shall be determined from Span Tables 15 and 16 of the Supplements respectively for sheet and tile roofs.

The size of top plates for the lower storey of a two-storey construction shall be determined from Span Table 46 of the Supplements for both sheet and tile roofs.

(b) Lower storey (a)Â Â Single or upper storey FIGURE 6.19 TOP PLATES

73

Amended 2001

74

Amended 2001

75

TABLE 6.2 FRAMING SIZES FOR NON-LOADBEARING INTERNAL WALLS Member

Minimum Size (mm)

Maximum spacing (mm)

35  70

—

2700 mm

70  35

600

3300 mm

90  35 or 2/70  35

600

3600 mm

90  35 or 2/70  35

600

4200 mm

90  45 or 2/9035

600

As for common studs

—

Top and bottom plates Common studs of maximum height

Studs supporting lintels NOTES: 1

Plates may be trenched up to 5 mm.

2

Studs may be notched up to 20 mm.

Table 6.2 is based on a F4 Stress grade or better.

76

6.3.6.2 Lintels in loadbearing walls

The size of lintels in loadbearing walls shall be determined from Span Tables 17 and 18 of the Supplements for single or upper storey or from Span Tables 47 and 48 of the Supplements for the lower storey of a two-storey construction for sheet and tile roofs respectively.

77

6.3.6 Lintels

(a) Single or upper storey (b) Lower storey

FIGURE 6.20 LINTELS

78

79

80

6.3.6.4 Lintels supporting concentrated roof loads The size of lintels supporting concentrated roof loads shall be determined from Span Tables 19 and 20 of the Supplements for sheet and tile roofs respectively. For area of roof supported, see Clause 2.6.5.

Calculate appropriate area of roof supported as per Clause 2.9.5.

81

6.3.7 Verandah beams (plates)

The size of verandah beams shall be determined from Span Tables 51A and 52 of the Supplements for single span and continuous spans respectively FIGURE 6.22 VERANDAH BEAMS 82

A=9375

A=9375

A=9375

A=9375 A=9375

A=7500

83

Amended 2001

84

Roof area supported = A/2 x B/2

Floor area supported = C/2 x D/2

FIGURE 6.23 POSTS SUPPORTING ROOF AND/OR FLOOR LOAD

END of SECTION 6

85

Optical Illusions and Visual Phenomena Want to confuse your eyes and brain a bit?

Yes? Then you may look at the pics ..

86

What happen here?

87

SECTION 7 ROOF FRAMING 7.1 GENERAL 7.1.1 Scope The Section sets out specific requirements for building practice, design and specification of roof framing members. Reference shall also be made to the footnotes for each member given in the Span Tables of the Supplements.

88

7.1.2 Types of roofs and limitations 7.1.2.1 General 7.1.2.2 Coupled roof R a fte r

R id g e b o a rd C o lla r tie

T o p p la te

T o p p la te U n d e r p u r lin

S tru t

C e ilin g jo is t

S tru ttin g beam

S tru t

7.1.2.3 Non - coupled roof 89

7.1.2.4 Trussed roof The design of a timber roof truss shall be in accordance with engineering principles and AS 1720.1. The wind design criteria shall be consistent with that used in this Standard (see Clause 1.4.2).

To p c h o rd

R o o fin g

R o o f b a tte n

W e b t ie (w e b b ra c e ) P it c h in g p o in t

C e ilin g O v e rh a n g

P it c h W ebs

C a n t ile v e r w e b

B o tto m c h o rd tie

C e ilin g b a t t e n

P it c h in g p o in t N a ilp la t e s

F a s c ia

B o tto m c h o rd

C a n t ile v e r N o m in a l s p a n O v e ra ll le n g th

O v e rh a n g

AS 4440-1997 Installation of nail-plated timber trusses should be referenced for correct practices when installing roof trusses.

90

7.2.1 Ceilings 7.2.2 Construction loads on ceiling framing 7.2.4 Ceiling joist 7.2.4.3 Connection to hanging beams H a n g in g b e a m

3 5 x 32 3 5 m m c le a t

P r o p r ie ta r y tie C e ilin g jo is t

7.2.4.4 Trimming around openings 7.2.4.5 Platforms in roof spaces 91

7.2.5 Hanging beams 7.2.5.1 General 7.2.5.2 End support of hanging beams H a n g in g b e a m C e ilin g jo is t

R a fte r

J o is ts fix e d w ith tie s o n a lte rn a te s id e s o f h a n g in g b e a m

T o p p la te

J a c k jo is t ( tr im m e r) B e a m b o lte d to ra fte r

Figure 7.3 Support of Hanging Beam with Jack Ceiling Joist (Trimmer) 92

7.2.6 Counter beams 7.2.6.1 General Counter beams may be provided to support hanging beams (see Figure 7.2 and 7.4).

End support of counter beams shall be similar to that for hanging beams (see Clause 7.2.5.2).

Where roof loads are required to be supported on counter beams they shall be designed as combined strutting/counter beams (see Clause 7.2.8).

R id g e b o a r d H a n g in g beam R a fte r

C e ilin g jo is t C o u n te r b e a m

Figure 7.2

S u p p o r ti n g w a ll 93

3 5 x 3 2 m m c le a t o r p r o p r ie t a r y t ie

P r o p r ie t a r y c o n n e c to r s s u c h a s jo is t h a n g e r s , o r 4 5 x 4 2 m m le d g e r s w it h 5 /3 .0 5 m m d ia .n a ils o r 2 /N o . 1 4 ty p e 1 7 s c r e w s

C o u n te r b e a m

H a n g in g b e a m

C e ilin g jo is t 2 5 m m c le a r a n c e Do you need this clearance?

FIGURE 7.4 FIXING HANGING BEAM TO COUNTER BEAM

94

7.2.8 Combined strutting/counter beams Combined strutting/counter beams shall be used to support roof loads and ceiling loads via hanging beams. They shall be located at right angles to hanging beams and parallel to ceiling joists.

Where counter beams are located between the ceiling joists, the 25 mm clearance specified for strutting beams is required.

Why - it doesn’t make sense

Additional strutting load C o m b in e d s t r u t tin g /c o u n te r b e a m s 3 5 x 3 2 m m c le a t o r p r o p r ie t a r y t ie

P r o p r ie t a r y c o n n e c to r s s u c h a s jo is t h a n g e r s , o r 4 5 x 4 2 m m le d g e r s w it h 5 /3 .0 5 m m d ia .n a ils o r 2 /N o . 1 4 ty p e 1 7 s c r e w s

H a n g in g b e a m

C e ilin g jo is t 2 5 m m c le a r a n c e

FIGURE 7.4 FIXING HANGING BEAM TO COMBINED STRUTTING/COUNTER BEAM 95

7.2.9 Strutting beams M in im u m e n d d im e n s io n 1 0 0 m m o r D /3 w h ic h e v e r is th e g r e a te r .

R a fte r U n d e r p u r lin

S tr u t t in g b e a m S tru t D

B lo c k t o p r o v id e S t r u t t in g b e a m s u p p o r t .

S tu d 2 5 m m c le a ra n c e a t m id s p a n o f S tr u tt in g b e a m

FIGURE 7.5 INSTALLATION OF STRUTTING BEAMS The ends of strutting beams may be chamfered to avoid interference with the roof claddings.

96

7.2.10 Underpurlins 7.2.10.1 7.2.10.2 7.2.10.3 7.2.10.4

R id g e b o a r d

General Joins in underpurlins Cantilevered underpurlins Support of underpurlins R a fte r s p a c in g

Rafter

U n d e r p u r lin Underpurlin

R a fte r

span R o o f s tru t

s p a n (b a c k s p a n ) M a x . c a n t ile v e r = 1 / 4 a llo w a b le b a c k s p a n M in . b a c k s p a n = 3 x a c tu a l c a n t ile v e r

97

7.2.11 Rafters 7.2.11.1 General Rafters shall be single length members or joined over supports.

Rafters in cathedral roofs carry both roof and ceiling loads.

7.2.11.2 Birdsmouthing D

1 /3 D m a x .

( a ) B ird s m o u th e d

M a x im u m o v e r h a n g 3 0 % s in g le s p a n v a lu e o f r a ft e r e x c e p t w h e re o v e rh a n g fo r a b ir d s m o u t h e d r a f te r p e r m it s a g re a te r o v e rh a n g

D

• • • •

W edge or fra m in g anchor

( b ) N o n - b ir d s m o u t h e d

FIGURE 7.28 RAFTER OVERHANG AND BIRDSMOUTHING 98

7.2.12 Ridgeboards 7.2.12.1 General Ridgeboards shall be provided to locate and stabilize rafter ends. Opposing pairs of rafters shall not be staggered by more than their own thickness at either side of their ridge junction.

7.2.12.2 Joins in ridgeboards J o in t s h a ll b e m id w a y b e tw e e n ra fte rs

R a fte r

R id g e b o a rd

F u ll d e p th o r c lo s e to fu ll d e p t h fis h p la t e s ( m in .1 9 m m th ic k ) , f it te d b e tw e e n ra fte rs o n b o th s id e s o f th e rid g e a n d f ix e d w ith m in .

6 /6 5 x 3 .0 5 m m d ia . n a ils o n e a c h s id e o f t h e jo in t

99

7.2.15 Roof strutting 7.2.15.1 Roof struts

Struts shall be provided to support roof members, such as underpurlins ridgeboards and hip and valley rafters. Struts shall be supported off walls, strutting beams or combined hanging/strutting beams.

R a fte r

U n d e r p u r lin

Rafter

M ax. 12 m m

N o t le s s th a n 3 8 m m

N o t le s s th a n 3 8 m m

max 35°

Nail

Vertical Struts

Strut perpendicular to rafter 100

7.2.15.3 Fan struts U n d e r p u r lin 9 0 x 3 5 m m s p re a d e r c le a ts e ith e r s id e o f s tru ts fix e d w ith M 1 2 th ro u g h b e lt

S tru t n a ile d to u n d e r p u r lin w ith 4 /7 5 m m n a ils S tru ts ( s e e T a b le 7 .5 ) E q u a l a n g le s n o t le s s th a n 4 5 o

M in . a n g le 6 0 t o h o r iz o n t a l

C h o c k n a ile d to p la te

o

E a c h s tru t 3 0 m m m in . b e a r in g to to p p la te

Figure 7.12 Fan or Flying Struts

S t iffe n e r

101

7.2.16 Collar ties Collar ties shall be provided in all coupled roof construction.

See Table 7.6 for size of collar ties.

R id g e b o a r d

U n d e r p u r l in

C o ll a r t ie R a fte r T o p p la te

T o p p la te S tr u t o

3 0 m in S t r u t t in g b e a m S tr u t

C e il in g jo i s t

F u ll- le n g th b lo c k in g p ie c e b e tw e e n b a s e s o f s tru ts

Figure 7.13 Opposing Struts

102

7.2.17 Hip ends Hip ends shall be constructed in accordance with the alternative methods shown in Figure 7.14.

W h e n a tie b o lt s y s te m is u s e d t o s u p p o r t t h e h ip / u n d e r p u r lin c o n n e c tio n , t h e u n d e r p u r lin m u s t b e s u p p o r te d a t th e fir s t c o m m o n r a fte r.

S tr u t a t ju n c t io n o f h ip a n d r id g e w h e n h ip o r v a lle y ra fte r s s u p p o rt u n d e r p u r lin s Span of u n d e r p u r lin

T ie - b o lt tru s s s y s te m

S in g le o r fa n s tr u t s u p p o r tin g u n d e r p u r lin

C ro w n e n d C r e e p e r r a fte r T h e u n d e r p u r lin t h a t s u p p o r ts th e c re e p e r r a f te r s in t h e h ip e n d m a y b e s u p p o r te d b y a tie b o lt tr u s s a s illu s t r a t e d o r a c o m b in e d h a n g in g / s tr u t t in g beam

H ip R a fte r

FIGURE 7.14 HIP END

A c a n tile v e r o f 2 5 % o f t h e m a x im u m a ll o w a b l e s p a n o f t h e u n d e p u r lin is p e r m it t e d t o s u p p o r t th e h ip r a fte r, p r o v id e d th e a c tu a l b a c k s p a n is a t le a s t t h r e e t im e s th e a c t u a l c a n tile v e r le n g t h , a n d p r o v id e d t h a t t h e s p a n is o n t h e lo n g s id e o f t h e r o o f .

103

7.2.19 Non-coupled roofs 7.2.19.1 General Non-coupled roofs shall have rafters, or raking roof beams, supported off walls, ridge beams and/or intermediate beams.

This roof system includes cathedral roofs (ceiling in line with roof) as well as other raftered roofs outside the limits for ‘coupled roof construction’ (e.g. roof pitch below 10).

7.2.19.2 Ridge and intermediateeams Ridge beams or walls shall be provided at the apex in the roof and shall be designed to support roof loads and ceiling loads (where required).

104

7.2.24.2 Boxed eaves

H a n g e r m in .

45 x 19 m m

1 2 m m m in . a llo w a n c e fo r s h rin k a g e

S o ffit b e a re r

(a ) H a n g e r s u p p o rt

( b ) W a l l f r a m e f i x in g

FIGURE 7.15 BOXED EAVES CONSTRUCTION 105

7.2.26 Lateral restraint of hanging, strutting, strutting/hanging beams, and the like

(a) Block skew nailed to beam and to support with 3/75 mm skewnails to each member

(b) Min 35 ď‚´ 32 mm tie nailed to top of beam and to support with 2/75 mm nails each end (see Note below)

(c) Galvanized strap nailed to support and top of beam with 2/30 ď‚´ 2.8 mm nails each end and to beam (see Note below)

NOTES: 1 Method given in (a) depend upon whether the ceiling joist is at 90O or parallel to the beam.

2 Methods given in (b) and (c) are particularly suitable for restraining strutting beams and strutting/hanging beams.

FIGURE 7.18 LATERAL RESTRAINT 106

7.3 MEMBER SIZES 7.3.1 General Member sizes shall be determined from the Span Tables of the Supplements for coupled or non-coupled roof construction, as appropriate (see Clause 2.7.4).

7.3.2 Ceiling battens 7.3.3 Ceiling lining and non- trafficable roof decking TABLE 7.1 7.3.2 Ceiling battens CEILING BATTEN SIZE

Rafter or truss spacing (mm) Ceiling batten grade

600

900

1200

Batten Spacing (mm) 300

450

600

300

450

600

300

450

600

F5 Unseasoned

38  38

38  38

38  38

38  38

38  38

38  38

38  50

38  75

38  75

F8 Unseasoned

25  38

25  38

25  38

25  50

38  38

38  38

38  38

38  38

38 50

F5 Seasoned

35  42

35  42

35  42

35  42

35  42

35  42

35  42

35  42

38  42

107

7.3.6 Ceiling joists

The size of ceiling joists shall be determined from Span Table 21 (without overbatten) or Span Table 22 (with overbatten) of the Supplements. Overbattens shall be a minimum of 35 x 70 mm F5.

For design parameters for ceiling joists, see Figure below C o n tin u o u s s p a n jo is t

R a fte r H a n g in g beam

O v e rb a tte n , if r e q u ir e d

S in g le - s p a n jo is t

C e ilin g jo is t s p a c in g C e ilin g jo is t span

Figure 7.19 Ceiling Joists

108

1700

F5

Single span 1500

2200

Continuous span

1900 109

7.3.7 Hanging beams

The size of hanging beams shall be determined from Span Table 23 of the Supplements.

Hanging beams shall support ceiling loads only via ceiling joists.

H a n g in g beam C e il in g jo is t

Ceiling load width

(CLW = ‘x’

'x '

/ 2)

H a n g in g beam span

FIGURE 7.20 HANGING BEAMS 110

111

7.3.8 Counter beams The size of counter beams shall be determined from Span Table 24 of the Supplements.

R id g e b o a r d C e ilin g jo is t

H a n g in g beam C o u n te r beam

Ceiling load width

‘X’

(CLW) = 2

x = total of hanging beam spans either side of the counter beam

'x '

FIGURE 7.21 COUNTER BEAMS

112

Ceiling load width (CLW) =

‘X’ 2

x = total of hanging beam spans either side of the counter beam

For Table input: Ceiling load width (CLW) = ‘X’ = Counter

2

beam spacing

113

7.3.9 Combined strutting/hanging beams The size of combined strutting/hanging beams shall be determined from Span Table 25 of the Supplements.

Combined strutting/hanging beams may support both roof loads from struts and ceiling loads from ceiling joists.

7.3.10 Combined counter-strutting beams

The size of combined counter-strutting beams shall be determined for Span Tables 26 of the Supplements.

Combined counter-strutting beams may support roof loads from struts and hanging beams from ceiling loads.

114

U n d e r p u r lin 'A '

Roof area supported RIDGE NOT STRUTTED 'B ' = (1/2)A x (3/4)B

R o o f s tru t

'x ' C o m b in e d H a n g in g /S t r u tt in g beam

Ceiling load width (CLW) =

X 2

FIGURE 7.22 COMBINED STRUTTING/HANGING BEAMS 115

116

Roof area supported RIDGE STRUTTED = (1/2)A x (1/2)B

R id g e b o a r d 'A '

U n d e r p u r lin H a n g in g beam

Ceiling load width R o o f s tru t

X (CLW) = 2

'x ' 'B ' C o u n te r/ S tr u tt in g beam

FIGURE 7.23 COMBINED COUNTER-STRUTTING BEAMS 117

118

7.3.11 Strutting beams The size of strutting beams shall be determined from Span Table 27 of the Supplements. Strutting beams shall support roof loads only.

The top edge of strutting beams shall be laterally restrained at their supports and intermediately at the strutting points (see Figure below).

FIGURE 7.18 LATERAL RESTRAINT 119

Area supported - FIGURE 7.24 STRUTTING BEAMS EXAMPLE: The STRUTTING BEAM span table (Table 25 to 27) requires a ‘Roof Area Supported (m2)’ input.

The strutting beam shown supports a single strut that supports an underpurlin.

U n d e r p u r lin

A

A/2 B/2

B The sum of, half the underpurlin spans either side of the strut (A/2), multiplied by the sum of half the rafter spans either side of the underpurlin (B/2).

S tru t

S t r u t t in g B e a m Span

The area required is the roof area supported by the strut. This is calculated as follows:-

S tr u ttin g B e a m

A B  Roof Area Supported = 2 2

(Watch carefully you need to understand this principle)

120

121

7.3.12 Underpurlins The size of underpurlins shall be determined from Span Table 28 of the Supplements.

R id g e b o a r d

R a fte r s p a c in g

U n d e r p u r lin

x

R a fte r

x

RWL – RIDGE STRUTTED

span R o o f s tru t

s p a n (b a c k s p a n ) M a x . c a n t ile v e r = 1 / 4 a llo w a b le b a c k s p a n M in . b a c k s p a n = 3 x a c t u a l c a n t ile v e r 122

123

7.3.13 Rafters and purlins 7.3.13.1 General The size of rafters or purlins shall be determined from Span Table 29 of the Supplements.

For rafters supporting roof loads only, see Figure 7.26 for design parameters.

Where rafters support both roof and ceiling loads, see Figure 7.27.

R id g e b o a r d

R a fte r s p a n (s in g le s p a n e x a m p le )

R id g e b o a r d

U n d e r p u r lin

R a fte r

C e il in g jo i s t

span x

R a fte r S p a c in g s

(a) Single span

R a fte r s p a n (c o n tin u o u s s p a n e x a m p le )

span x R a fte r S p a c in g s

(b) Continuous span 124

125

7.3.14 Ridge or intermediate beams — Cathedral or skillion roofs The size of ridge or intermediate beams in non-coupled cathedral or skillion roofs shall be determined from Span Tables 30 and 31 of the Supplements for single and continuous spans respectively.

S u p p o r ts ( p o s t, w a ll e tc .)

R id g e b e a m

R id g e b e a m

In t e r m e d ia t e b e a m

S u p p o r t in g w a ll o r in t e r m e d ia te beam

R a fte r

'x '

'x '

S u p p o r ts ( p o s t , w a ll e tc .)

'y ' = s u p p o rts

(a) Ridge beams (b) Intermediate beams

What is the RLW ?

126

back 132

127

back 131

128

7.3.15 Roof battens The size of roof battens shall be determined from Span Table 32 of the Supplements.

R o o fin g b a tte n

B a tte n s p a c in g

R a fte r o r tr u s s

B a tte n span

O v e rh a n g

129

7.3.17 Other members or components Table 7.6

gives details of requirements for miscellaneous roof framing members not given in the Span Tables of the Supplements.

130

Table 7.6 other members and components Member

Ridgeboards

Hip rafters

Application

Page 110 Minimum size (mm)

Unstrutted ridge in coupled roof

Depth not less than length of the rafter plumb-cut  19 thick

Strutted ridge in coupled roof with strut spacing not greater than 1800 mm

Depth not less than length of the rafter plumb-cut  19 thick

Strutted ridge in coupled roof with strut spacing greater than 1800 to 2300 mm

Depth not less than length of the rafter plumb-cut  35 thick

Stress grade F11/MGP15 minimum and no less than rafter stress grade

50 greater in depth than rafters  19 thick (seasoned) or 25 thick (unseasoned)

Stress grades less than F11/MGP15

50 greater in depth than rafters  min. thickness as for rafters

Valley rafters

Minimum stress grade, as for rafters

50 greater in depth than rafters with thickness as for rafter (min. 35)

Valley boards

See Note

19 min. thick  width to support valley gutter

NOTE: 175  25  6 mm hardwood weatherboards may also be used for valley boards.

End of Section 7

131

SECTION 8

RACKING (BRACING) AND SHEAR FORCES 8.1 GENERAL Permanent bracing.

Appropriate connection.

132

G a b le e n d b r a c in g

C ro ss o r sh e e t b r a c in g

C ro ss o r sh e e t b r a c in g S u b flo o r c r o s s - b ra c in g , c a n tile v e r e d s tu m p s o r b r a c in g w a ll W in d

Without ceiling diaphragm

With ceiling diaphragm

133

8.3 WALL AND SUBFLOOR BRACING 8.3.1 General Bracing shall be designed and provided for each storey of the

house and for the subfloor, where required, in accordance with the following procedure: (a)

Determine the wind classification

(b)

Determine the wind pressure

(c)

Determine area of elevation

(d)

Calculate racking force

(e)

Design bracing systems for— (i) subfloors (see Clause 8.3.5); and (ii) walls (see Clause 8.3.6).

(f)

Check even distribution and spacing

(g)

Check connection of bracing to roof/ceilings and floors 134

W in d f o rc e s o n th e r o o f a r e c a r r ie d to t h e c e ilin g s h e e tin g ( c e i li n g d i a p h r a g m ) v ia t h e r o o f & c e i lin g f r a m i n g W i n d f o r c e s o n t h e t o p h a lf o f t h is w a ll a r e c a r r i e d t o t h e c e il in g s h e e t in g ( c e ili n g d ia p h r a g m ) v ia t h e w a l l & c e il in g f r a m i n g W i n d f o r c e s o n t h e b o t t o m h a lf o f t h is w a ll a r e c a r r ie d d ir e c t t o t h e g r o u n d v ia t h e w a ll fr a m in g , s la b & fo o tin g s .

W in d f o r c e s o n th e r o o f a r e c a r r ie d to t h e c e ilin g s h e e t in g ( c e ilin g d ia p h r a g m ) v ia t h e r o o f & c e il in g fr a m in g W in d f o r c e s o n th e t o p h a lf o f t h is w a ll a r e c a r r i e d t o t h e c e il in g s h e e t in g ( c e ili n g d ia p h r a g m ) v ia th e w a ll & c e ilin g f r a m in g W i n d f o r c e s o n t h e b o t t o m h a lf o f t h is w a ll a r e c a r r ie d t o t h e f lo o r in g ( flo o r d ia p h r a g m ) v ia th e w a ll & flo o r fr a m in g W in d f o r c e s o n t h e t o p h a lf o f t h is w a ll a r e c a r r ie d t o t h e f lo o r in g ( flo o r d ia p h r a g m ) v ia th e w a ll & flo o r f r a m in g W in d f o r c e s o n t h e b o t t o m h a lf o f t h is w a ll a r e c a r r ie d d ir e c t t o t h e g r o u n d v ia t h e w a ll f r a m in g , s la b & f o o t in g s .

C e ilin g d ia p h r a g m W in d fo r c e s tra n s fe re d to th e 'c e ilin g d ia p h r a g m ' a r e c a r r ie d d o w n to th e s la b a n d th e g r o u n d v ia b r a c in g w a lls .

C e ili n g d ia p h r a g m

W in d fo rc e s tr a n s fe re d to t h e 'c e i lin g d i a p h r a g m ' a r e c a r r i e d d o w n t o t h e '; f l o o r d ia p h r a g m ' v i a b r a c i n g F lo o r d ia p h r a g m W in d fo rc e s tra n s fe re d to th e 'f l o o r d i a p h r a g m ' a r e c a r r ie d d o w n to th e s la b / f o o t in g s & g r o u n d v ia b r a c in g w a lls .

135

1. Bracing may affect top and/or bottom plate sizes and/or stud spacing.

2. Bolts or straps 3. Tie-down associated with braces methods may or bracing sheets affect member themselves may be sizes able to be utilised for tie-down.

3 5 m m ( m in .)

6 b o lt O

2 b o lt O 5 b o lt O 4 b o lt O

Verandah beam to post.

Table 9.20(i)

136

8.2 TEMPORARY BRACING Temporary bracing is necessary to support wind and construction loads on the building during construction.

8.3.2 Wind pressure on the building Wind pressures on the surfaces of the building depend on the wind classification, width of building and roof pitch. Tables 8.1 to 8.5 give pressures depending on these variables.

137

When wind flows over a building it applies different pressures (forces) on a flat vertical wall to that on the sloping roof surface.

Pressure on roof - 0.77 kPa* Pressure on wall - 1.10 kPa* * These values are indicative only and will vary with roof pitch, building height to depth ratio etc.

The tables need to know the ratio between how much roof area the wind ‘sees’ as opposed to how much wall area the wind ‘sees’. The building width and roof pitch will establish this ratio.

138

Wind direction 1

To determine the pressure on this ‘part’ of the building in Direction 1. Table 2 (and 3 if also two-storey) will be used even though this is the ‘shortest side’.

Wind direction 2 ... and in Direction 2. Table 4 (and 5 if also two-storey) will be used even though this is the ‘longest side’.

139

8.3.3 Area of elevation The wind direction used shall be that resulting in the greatest load for the length and width of the building, respectively.

As wind can blow from any direction, the elevation used shall be that for the worst direction.

For example ...........

Sloping roof surface vertical wall

All vertical surface ď œď€ this is the worst wind direction

140

As indicated by Figures 8.2 (A) and Note 1, the area of an elevation includes only the top half of the wall.

Note: 1 - h = half the height of the wall (half of the floor to ceiling height).

This is the area used to calculate single or upper storey bracing

Ceiling diaphragm

Floor Slab

141

8.3.4 Racking force The racking force on the building shall be determined by using the method given in this Clause or by using the alternative method given in Appendix G. NOTE: The alternate method given in Appendix G will give a more conservative result.

We will use Appendix G for RACKING FORCES – ALTERNATIVE PROCEDURE 142

8.3.5 Sub-floor bracing 8.3.5.2 General All lateral loads (wind, earthquake, and the like) shall be resisted by the foundations (ground) of the building. Roof and wall bracing is designed to transfer these loads to the floor plane. Below the floor, the subfloor support structure shall be designed to transfer these loads to the footings.

8.3.5.3 Soil classification reduction factor The bracing capacities given in Tables 8.7 to 8.13 are based on soil classifications A, S and M. When other soil classification are found, the capacity shall be reduced by multiplying the values in these tables by the load capacity reduction factor given in Table 8.6.

143

TABLE 8.15 COLUMN BRACING CAPACITY Height of column above ground (mm)

Column details

Plan size (mm)

600 or less

Concrete and masonry

Footing plan size or diameter (mm)

Footing depth D (mm)

Bracing capacity (kN)

Reinforcement

Timber diameter (mm)

Steel (mm)

M200200

1-Y12

125

76763.2

350350

900

6

601 to 900

M200200

1-Y12

150

76764.0

350350

900

4.5

901 to 1800

C200200 M200400 M300300

4-R10

200

—

350350

900

3

1801 to 2400

C200200 M200400 M300300

4-Y12

225

—

400  400

900

3

2401 to 3000

C250250 M200400 M300300

4-Y12

250

—

600600

900

2.3

NOTES: 1

C = reinforced concrete column; M = reinforced concrete masonry.

2

Footing depth may be reduced to 600 mm when enclosed by a minimum of 100 mm thick concrete slab cast on the ground and of a minimum size of 6 m2.

3

For concrete and masonry columns and walls, see AS 3600 and AS 3700, respectively.

4

For bearer tie-down, see Section 9.

144

1 /M 1 2 o r 2 /M 1 0 b o lts

1 o 2 b

1 o 2 b

/M 1 2 r /M 1 0 o lt s

50x6 m m M . S . P la te

/M 1 2 r /M 1 0 o lt s

S te e l post

D

1 /M 1 2 o r 2 /M 1 0 b o lts

1 o 2 b

T im b e r c o lu m n

T im b e r c o lu m n

D

D

D 150 m m

150 m m

150 m m

C o n c re te 8 m m P la t e

/M 1 2 r /M 1 0 o lt s

C o n c re te 12 b o lt o r r o d

C o n c re te 12 b o lt o r r o d

N o -fin es co nc re te sh all be use d fo r e xte rn al h a rd w o o d c o lu m ns

N O T E : F o r g u id a n c e o n d u ra b ility , se e A p p e n d ix C .

FIGURE 8.4 CONCRETE, MASONRY AND STEEL BRACING COLUMNS 145

TABLE 8.16 UNREINFORCEDMASONRYBRACINGCAPACITY Bracing Description

capacity (kN/m)

Subfloor of single storey with brick veneer over

3

Subfloor of two storeys with brick veneer over

7.5

Subfloor of single storey with clad frame over

1.5

Subfloor of two storeys with clad frame over

3

Tie-down shall be provided frombearers to footings

146

8.3.6 Wall bracing 8.3.6.1 General Walls shall be permanently braced to resist horizontal racking forces applied to the building. Wall bracing shall be designed to resist racking forces equal to or greater than the forces calculated from Clause 8.3.4.

The total capacity of bracing walls shall be the sum of the bracing capacities of individual walls. See Table 8.18 for the capacity of structural bracing walls.

8.3.6.2 Nominal wall bracing Nominal wall bracing is wall framing lined with sheet materials such as plywood, plasterboard, fibre cement or hardboard, or the like, with the wall frames nominally fixed to the floor and the roof or ceiling frame.

147

Where sheet wall lining is placed over the top of a structural brace, the value of the sheet wall lining can not be given its nominal value for the section that overlaps the structural brace.

S tr u c tu r a l b r a c e

T h is s e c tio n o f w a ll s h e e tin g is c o u n t e d a s n o m in a l b r a c in g .

M in im u m le n g t h 4 5 0 m m .

T h e s e c t io n o f w a ll s h e e t in g th a t o v e r la p s th e S tr u c tu ra l b ra c e m u s t n o t b e c o u n te d a s n o m in a l b r a c in g .

We will use only three (3) Types of bracing, namely:

Type (b), (d) and (g) 148

TABLE 8.18 (continued)

Type of bracing

T A B LE 8.18 (con tinued ) (d)

Bracing capacity (kN/m)

Double diagonal tension or m etal strap bra ces

3 0 x 0 .8 m m g a lv . m e ta l s tra p lo o p e d o v e r p la te a n d fix e d to s tu d w ith 4 /3 0 x 2 .8 m m  g a lv . fla th e a d n a ils ( o r e q u iv a le n t) to e a c h e n d .

A lte r n a tiv e ly , p r o v id e s in g le s tr a p s t o b o t h s id e s , w it h 4 n a ils p e r s tr a p e n d , o r e q u iv a le n t a n c h o rs o r o th e r fa s te n e rs

3 0  to 60

1 8 0 0 m m m in . to 2700 m m m ax.

3 .0

3 0 x 0 .8 m m ( o r e q u iv a le n t) te n s io n e d g a lv. m e ta l s tra p s n a ile d to p la te s w ith 4 /3 0 x 2 .8 m m  g a lv . f la th e a d n a ils ( o r e q u iv a le n t ) to e a c h e n d F o r fix in g o f b o tto m p la te to flo o r f ra m e o r s la b , r e f e r to C la u s e 8 .3 . 6 .1 0

149

TABLE 8.18 (continued)

150

A

A

B D

B

C

C D

W in d d ir e c tio n

E

W in d d ir e c tio n

T o ta l b ra c in g s tr e n g th = A + B + C + D , e tc .

N O T E : A , B , C a n d D a re th e d e s ig n s tre n g th s o f in d iv id u a l b ra c in g w a lls . ( a ) R ig h t a n g le s to lo n g s id e

( b ) R ig h t a n g le s to s h o r t s id e

FIGURE 8.5 LOCATION OF BRACING 151

By adding an intermediate brace, the diaphragm is broken into two.

Individually they have a smaller length to depth ratio and will transfer the wind loads effectively 152

8.3.6.9 Fixing of top of bracing walls All internal bracing walls shall be fixed to the floor for lower storey bracing walls, the ceiling or roof frame, and/or the external wall frame, with structural connections of equivalent shear capacity to the bracing capacity of that particular bracing wall.

Wind loads, transferred from the roof and walls to ceiling and floor diaphragms are then transferred through braces to the ground.

These braces, however, can only transfer these loads if the brace is connected to the ceiling or floor above and the floor below.

In te rn a l b r a c e n o t c o n n e c te d t o c e ilin g d ia p h r a g m

In te rn a l b r a c e n o t c o n n e c te d to flo o r d ia p h r a g m

153

R id g e b o a rd

A lte r n a tiv e b r a c in g : o p p o s in g b r a c e s f ro m r id g e b o a r d t o in t e r n a l w a lls a t a p p r o x im a te ly 4 5 

R a fte r

G a b le e n d

M in . 1 9 x 9 0 m m o r 2 5 x 7 5 m m b r a c e a t a p p ro x im a te ly 4 5  to r a ft e rs o n b o t h s id e s o f r id g e

FIGURE 8.9 GABLE ROOF BRACING

END OF SECTION 8 154

SECTION 9 FIXINGS AND TIE-DOWN DESIGN 9.1

SCOPE

This Section specifies the fixing requirements necessary to ensure the structural adequacy of the interconnection of the various framing members in a house.

Figure 9.1(a), 9.1(b) and 9.1(c) illustrate the typical load actions that are accounted for in this Section.

155

9.2 GENERAL CONNECTION REQUIREMENTS 9.2.1

General The general details given in Clauses 9.2.2 to 9.2.11 shall apply to all connections and fixings.

9.2.2 Corrosion protection 9.2.3 Straps, bolts, screws, coach screws and framing anchors 9.2.4 Steel washers 9.2.5 Drilling for bolts 9.2.6 Drilling for coach screws 9.2.7 Screw and coach screw penetration 9.2.8 Framing anchor and strap nails 9.2.9 Alternative metal strap size 9.2.10 Joining of top plates 9.2.11 Tie-down of members joined over supports 156

Uplift capacities of these types of joints, where bolts, straps etc are in shear may need to be reduced.

5 0 m in .

5 0 m in .

5 0 m in .

(a) Type 1

5 0 m in .

( H a lv e d J o in t )

FIGURE 9.3 JOINING MEMBERS AT SUPPORTS 157

REFERENCE DETERMINE IF NOMINAL OR SPECIFIC FIXINGS ARE REQUIRED

SPECIFIC FIXINGS REQUIRED YES

YES

UPLIFT

SHEAR

Clause 9.4

NOMINAL ONLY

CLAUSE 9.5 AND TABLE 9.4

DETERMINE UPLIFT LOAD WIDTH OR AREA

Clause 9.6.2 and Figure 9.4

DETERMINE UPLIFT FORCE

Clause 9.6.4 for use with uplift load area or Tables 9.6 to 9.14 for use with ULW

DETERMINE JOINT GROUP

Clause 9.6.5

SELECT TIE­DOWN CONNECTION

Tables 9.16 to 9.25

CHECK NOMINAL BRACING AND TIE­DOWN CONNECTIONS TO SEE IF ADDITIONAL CONNECTIONS OR MODIFICATIONS ARE REQUIRED FOR SHEAR

Clause 9.4 and Table 9.3 for joists and bearers, and Clause 9.7.6 and Table 9.29 for top of external non­loadbearing walls

IF YES DETERMINE SHEAR FORCE

SELECT SHEAR CONNECTION

Clause 9.7.5 and Clause 9.7.6 Tables 9.27, 9.28 for the joists and bearers, and Table 9.30 for the top of walls

FIGURE 9.4 FLOW CHART SHOWING PROCDURE FOR TIE-DOWN REQUIREMENTS 158

9.4 NOMINAL AND SPECIFIC FIXING REQUIREMENTS For all houses and wind speeds, the nominal (minimum) fixing requirements shall be in accordance with Clause 9.5.

9.5 NOMINAL FIXINGS (MINIMUM FIXINGS) 9.6 SPECIFIC TIE-DOWN FIXINGS

9.6.1

General

This Clause provides details for structural connections to resist uplift and shear forces (lateral loads) in floor framing, wall framing and roof framing.

Continuity of tie-down shall be provided from the roof sheeting to the foundations.

9.6.2 9.6.3

Uplift load width (ULW) Application

159

ULW for roof and wall frames U LW

U LW

U LW

U LW

U LW

U LW

ULW generally does differ significantly from RLW, CLW and FLW for most coupled roofs

U LW

U LW

U LW

U LW

U LW

ULW for floor frames (b) Traditional raftered (pitched roof) construction FIGURE 9.5 ROOF UPLIFT LOAD WIDTH ULW FOR WIND

160

9.6.4 Wind uplift forces

The wind uplift forces that occur at tie-down points can be determined from Table 9.5 by multiplying the nett uplift pressure (e.g., allowance for typical dead load deducted) by the area of roof contributing to tie-down at that point.

back 161

Roof area to be tied down (m2) =ULW x Fixing Spacing = 4.0 m x 0.9 m = 3.6 m2 D is t a n c e t o n e x t tie - d o w n = 1200 m m

F ix in g ½ ope ½ th e th e n e

O p e n in g w id t h = 2400 m m

S p a c in g = n in g w id th + d is ta n c e to x t tie - d o w n

Calculating tiedown beside an opening T ie - d o w n lo c a tio n T ie - d o w n lo c a tio n

162

Sheet roof

600

900

370

0.15

0.29

0.22

0.41

0.35

0.65

0.53

0.97

450

0.18

0.35

0.26

0.50

0.42

0.79

0.64

1.1

600

0.24

0.47

0.35

0.66

0.57

1.0

0.86

1.5

750

0.31

0.59

0.44

0.83

0.71

1.3

1.0

1.9

900

0.37

0.71

0.53

1.0

0.85

1.5

1.2

2.3

1200

0.49

0.94

0.71

1.3

1.1

2.1

1.7

3.1

370

0.23

0.44

0.33

0.61

0.52

0.97

0.79

1.4

450

0.28

0.53

0.40

0.75

0.64

1.1

0.96

1.7

600

0.37

0.71

0.53

1.0

0.85

1.5

1.2

2.3

750

0.46

0.88

0.66

1.2

1.0

1.9

1.6

2.9

900

0.55

1.0

0.79 0.79

1.2

2.3

1.9

3.5

1200

0.73

1.4

1.0

1.5 1.5

1.7

3.1

2.5

4.7

2.0

163

RAFTER/TRUSS TIE_DOWN The tie-down requirement for each rafter/truss is calculated by multiplying the appropriate ULW by the fixing spacing and then multiplying the result by the appropriate Net Uplift Pressure from Table 9.5 T ie - d o w n w a ll

T ie - d o w n w a ll

U LW 4200

U LW 4200

U LW 2400

T ie - d o w n beam U LW 3600

T ie - d o w n w a ll U LW 2400

R a fte r T ie - d o w n

T ru s s T ie - d o w n

600

T ie - d o w n w a ll

7200

T ru s s e d ro o f

600

600

7200

C a th e d ra l ro o f

600 164

9.6.5 Joint group TABLE 9.15 JOINT GROUPS Species or species group

Joint group

Seasoned softwood (radiata, slash and other plantation pines)

Seasoned — Free of pith

JD4

Seasoned — Pith-in

JD5

Australian hardwood (non-ash type from Qld, NSW, WA etc.)

Unseasoned

Australian hardwoods (ash type eucalyptus from Vic, TAS, etc.)

Unseasoned

Cypress

Unseasoned

J3

Unseasoned

J4

Douglas fir (Oregon) from North America

Elsewhere

Seasoned See Note 2

Seasoned See Note 2

Seasoned Unseasoned

J2 JD2 J3 JD3

JD4 J5

Seasoned

JD5

Spruce pine fir (SPF)

Seasoned

JD6

Hem-fir

Seasoned

JD5

NOTES: 1

The appropriate joint group for a single timber species can be determined by reference to Appendix H, or AS 1720.2.

2

For timber with a joint group of JD2 or JD3, the values given in this Standard for J2 may be used.

165

Large arrows indicate direction of load.

FIGURE 9.6 JOINT GROUP SELECTION

166

Joint group (J, JD rating) shall be based on the w eakest of either m em ber as the design strength is controlled by the nails or screws in shear in both m em bers (d) Joint type 4 Joint group (J, JD rating) shall be based on the w eakest of either m em ber as the design strength is controlled by the nails w orking in shear in both m em bers (e) Joint type 2

Large arrows indicate direction of load.

FIGURE 9.6 JOINT GROUP SELECTION

167

TABLE 9.16 UPLIFT CAPACITY OF BEARER TIE-DOWN CONNECTIONS Uplift capacity (kN)

Position of tie-down connection

Unseasoned timber Seasoned timber

Bearers to stumps, posts, piers

J2

(c)

J3

J4

JD4

JD5

JD6

N o . o f b o lts 7 0 m m m in .

2 b o lt d ia .

B o lt s a s p e r ta b le 70 m m m in .

6 b o lt d ia .

5 b o lt d ia .

4 b o lt d ia .

T im b e r post

1 /M 1 0

5 .7

5 .2

3 .6

5 .2

4 .5

3 .9

1 /M 1 2

8 .1

6 .8

4 .7

7 .4

6 .4

5

2 /M 1 0

13

10

7 .3

12

11

8 .3

2 /M 1 2

17

14

9 .4

17

14

10

2 /M 1 6

26

20

14

27

20

13

2

2

2

2

2

2

(d ) N a ils o r s p ik e s m a y b e r e q u ir e d ( s e e C la u s e 9 . 7 ) M 1 2 c r a n k e d b o lt th ro u g h b e a re r w ith M 1 2 b o lt th ro u g h s tu m p

168

TABLE 9.19 UPLIFT CAPACITY OF WALL FRAME TIE-DOWN CONNECTIONS Position of tie-down connection Studs to plates

Uplift capacity (kN) Unseasoned timber J2

( a )

J3

J4

Seasoned timber JD4

JD5

JD6

H a n d d r iv e n n a ild ia .

2 th ro u g h n a ils a s p e r ta b le in to e n d g r a in

2 /3 .1 50 .3 20 .2 70 .2 40 .1 70 .1 10 .0 8

4 0 m m m in . p e n e tr a tio n

2 /3 .7 50 .3 70 .3 20 .2 90 .2 20 .1 30 .1 0 G lu e c o a te d o rd e f o r m e d s h a n k m a c h in e d r iv e n n a ild ia .

2 /3 .0 50 .4 80 .4 10 .3 60 .2 60 .1 70 .1 2

4 0 m m m in . p e n e tr a tio n

2 /3 .3 30 .5 60 .4 80 .4 30 .3 30 .2 00 .1 4

169

TABLE 9.21 UPLIFT CAPACITY OF RAFTER AND TRUSS TIE-DOWN CONNECTIONS Uplift capacity (kN) Position of tie-down connection

Unseasoned timber

Rafters/trusses to wall frame or floor frame (a)

J2

J3

Seasoned timber

J4 JD4 JD5 JD6

Hand-driven nail dia.

2 /7 5 m m s k e w n a ils a s p e r ta b le

3.15 0.97 0.82 0.71 0.51 0.34 0.24 3.75

1.1 0.97 0.87 0.66 0.40 0.29

Glue-coated or deformed shank machine-driven nail dia.

The uplift capacities given in this Item are applicable to the joint, not individual nails.

3.05

1.5 1.2 1.1 0.77 0.50 0.36

3.33

1.7 1.5 1.3 0.99 0.60 0.43

(b)

F r a m in g a n c h o r a s p e r t a b le , 4 /2 . 8 m m  n a ils to e a c h e n d

No. of anchors

1

4.9 3.5 2.5 3.5 2.9 2.2

2

8.3 5.9 4.2 5.9 4.9 3.7

170

End of Section 9 End of Presentation

Thank you for your attention !

171