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Chapter 5. Examples

5.1 Example 1Single-storey house in an urban area

Design wind loads are required for a single-storey house in the Sydney metropolitan area.The relevant information is as follows:

Location: western suburbs of Sydney (Region A2).

Terrain: Suburban terrain for all directions.

Topography: ground slope less than 1 in 20 for greater than 5 kilometresin all directions.

Dimensions: average roof height: 4.35 metresHorizontal dimensions, including entrance porch on south side (Figure

5.1) : 24 metres 12 metres

Porch: 2.4 14.5 m

Gable roof with 15 degrees pitch. Hip on west end. 0.6 m eaves.

Building orientation : major axis is East-West.

Timber frame construction. Wall studs are spaced at 0.4 m. Roof trussesare spaced at 1.2 m.

The building walls are considered equally permeable.

Figure 5.1 Plan of single-storey house

This house is used as an example in the Guide to the Use of the Wind Load provisions of

ASCE 7-02 [21]. Its use in the present Design Guide allows for a comparison of the two

Standards for this building.

Regional wind speed

According to the Building Code of Australia (BCA), the structure should be treated asImportance Level 2. Hence take average recurrence interval, R, equal to 500 years.

From Table 3.1in AS/NZS1170.2, VR= 45 m/s (Region A)

24 m

12 m

8

9

7

10

11

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Wind direction multipliers for Sydney (Region A2) are given in Table 3.2. Values range

from 0.80 (N, NE, E) to 1.0 (W).

z=h=4.35 m, For Terrain Category 3, Mz,cat= M4.35,cat3= 0.83 (Table 4.1(A))

Shielding

Since the building is surrounded by suburban development, assume a Shielding

Multiplier, Ms, of 0.85 for all directions.

Topography

Topographic Multiplier, Mt= Mh = 1.0

Site wind speed

Site wind speed for North direction, Vsit,N = 45(0.80)(0.83)(0.85)(1.0) = 25.4 m/s

(Equation 2.2)

For all wind directions, site wind speeds are calculated in the following table.

Direction V500

(m/s)

Md Mz,cat Ms Mt Vsit,(m/s)

N 45 0.80 0.83 0.85 1.0 25.4

NE 45 0.80 0.83 0.85 1.0 25.4

E 45 0.80 0.83 0.85 1.0 25.4

SE 45 0.95 0.83 0.85 1.0 30.2

S 45 0.90 0.83 0.85 1.0 28.6

SW 45 0.95 0.83 0.85 1.0 30.2W 45 1.00 0.83 0.85 1.0 31.7

NW 45 0.95 0.83 0.85 1.0 30.2

Design wind speeds

In this case, the building is orientated exactly N-S and E-W, and the design wind speeds,

Vdes, can be obtained by inspection from Vsit, in the above table, for the four winddirections orthogonal to the building walls:

Vdes,N= 30.2 m/s (largest from NW to NE sector)Vdes,E= 30.2 m/s (largest from NE to SE sector)

Vdes,S= 30.2 m/s (largest from SE to SW sector)

Vdes,W= 31.7 m/s (largest from SW to NW sector)

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Aerodynamic shape factor

External pressure coefficients, Cp,eWindward walls : +0.7 (Table 5.2(A))

Leeward walls (normal to long axis): -0.3 (Table 5.2(B))Leeward walls (normal to short walls): -0.3

Side walls (first 4.35 m from windward edge): -0.65 (Table 5.2(C))

Side walls (4.35 m to 8.7 m): -0.5Side walls (8.7 m to 13.05 m): -0.3

Side walls (beyond 13.05 m): -0.2

Roofupwind slope (normal to long axis: h/d = 4.35/12=0.36): -0.59, -0.13 (Table 5.3(B))Roofdownwind slope and hip end (normal to long axis: h/d = 4.35/12=0.36): -0.5 (Table

5.3(C))

Roofupwind slope (normal to short walls: h/d = 4.35/24=0.18): -0.5, 0.0 (Table 5.3(B))Roofdownwind slope (normal to short walls: h/d = 4.35/24=0.18): -0.5 (Table 5.3(C))

Roofcrosswind slope, R (normal to short walls: first 4.35 m from w.e): -0.9, 0.4 (Table

5.3(A))

Roofcrosswind slope, R (normal to short walls: 4.35 m to 8.7m from w.e): -0.5, 0.0(Table 5.3(A))

Roofcrosswind slope, R (normal to short walls: 8.7 m to 13.05 m from w.e): -0.3, +0.1

(Table 5.3(A))Roofcrosswind slope, R (normal to short walls: beyond 13.05 m from w.e): -0.2, +0.2

(Table 5.3(A))

Area reduction factors (Table 5.4)

For wall studs (windward or leeward wall) Ka= 1.0 (Section 5.4.2)

For roof trusses : tributary areas 1.2 9.75 = 11.7 m2. Hence Ka= 0.99 1.0 (by interpolation)

For foundation loads : tributary area = 24 12 = 288 m2. Hence Ka= 0.8

Local pressure factors (Table 5.6)

a = minimum of 0.2 12 m = 2.4 m, or 4.35 m. a = 2.4 mlimiting tributary areas for local pressure factors : 0.25a

2= 1.44 m

2

a2= 5.76 m

2

Internal pressures(Section 5.3)

The building can be considered to have all walls equally permeable.

In this case, Cp,i= -0.3 or 0.0 (Table 5.1(A))

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Action combination factors

When internal pressure is greater than 0.2 in magnitude, Cases (f) and (h) in Table 5.5mayapply (two effective surfaces) and Kc= 0.9

Otherwise, Kc= 1.0

Dynamic response factor

Cdyn= 1.0 (natural frequency greater than 1.0 Hertz) (Section 6.1)

Design wind pressure (major framing members) ul timate limit states:

North wall

As windward wall (north wind direction):

Cfig (external) = Cp,eKaKc,e= +0.7 (1.0) (0.9) = 0.63pext= (0.5 air) Vdes,2CfigCdyn= (0.5)(1.2) (30.2)

2(0.63)(1.0) = 345 Pa = 0.35 kPa

Cfig (internal) = Cp,iKc,i= -0.3 (0.9) = -0.27 pint= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.27)(1.0) = -148 Pa = -0.15 kPa

Net pressure across windward wall surface = 0.35-(-0.15) = 0.50 kPa

As leeward wall (south wind direction):

Cfig (external) = Cp,eKaKc,e= -0.3 (1.0) (1.0) = -0.3 pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.3)(1.0) = -164 Pa = -0.16 kPa

Cfig (internal) = Cp,iKc,i= 0.0 (1.0) = 0.0 pint= 0 kPa

Net pressure across wall surface = -0.16 kPa (acting outwards)

As side wallwest wind direction:

For length 0 to 1h (0 to 4.35m) from west edge:

Cfig (external) = Cp,eKaKc,e= -0.65 (1.0) (1.0) = -0.65pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (31.7)

2(-0.65)(1.0) = -392 Pa = -0.39 kPa

Cfig (internal) = Cp,iKc,i= 0.0 (1.0) = 0.0 pint= 0 kPa


For length 1h to 2h (4.35 m to 8.7 m) from west edge:


2CfigCdyn= (0.5)(1.2) (31.7)

2(-0.5)(1.0) = -301 Pa = -0.30 kPa

pint= 0 kPaNet pressure across wall surface = -0.30 kPa (acting outwards)

For length 2h to 3h (8.7 m to 13.05 m) from west edge:Cfig (external) = Cp,eKaKc,e= -0.3 (1.0) (1.0) = -0.3 pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (31.7)

2(-0.3)(1.0) = -181 Pa = -0.18 kPa

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pint= 0 kPa

Net pressure across wall surface = -0.18 kPa acting outwards)

As side walleast wind direction:

For length 0 to 1h (0 to 4.35m) from east edge:Cfig (external) = Cp,eKaKc,e= -0.65 (1.0) (1.0) = -0.65pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.65)(1.0) = -356 Pa = -0.36 kPa

pint= 0 kPa


For length 1h to 2h (4.35 m to 8.7 m) from east edge:


2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.5)(1.0) = -274 Pa = -0.27 kPa


For length 2h to 3h (8.7 m to 13.05 m) from east edge:Cfig (external) = Cp,eKaKc,e= -0.3 (1.0) (1.0) = -0.3 pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.3)(1.0) = -164 Pa = -0.16 kPa

pint= 0 kPa

Net pressure across wall surface = -0.16 kPa (same as leeward wall case)

East wall.

As windward wall (east wind direction):

Cfig (external) = Cp,eKaKc,e= +0.7 (1.0) (0.9) = 0.63pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (30.2)

2(0.63)(1.0) = 345 Pa = 0.35 kPa


2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.27)(1.0) = -148 Pa = -0.15 kPa

Net pressure across wall surface = 0.35-(-0.15) = 0.50 kPa

As side wallnorth wind direction:

For length 0 to 1h (0 to 4.35m) from north edge:


2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.65)(1.0) = -356 Pa = -0.36 kPa

Cfig (internal) = Cp,iKc,i= 0.0 (1.0) = 0.0

pint= 0 kPaNet pressure across wall surface = -0.36 = -0.36 kPa (acting outwards)

For length 1h to 2h (4.35 m to 8.7 m) from north edge:


2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.5)(1.0) = -274 Pa = -0.27 kPa


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As side wallsouth wind direction:

For length 0 to 1h (0 to 4.35m) from south edge:

Cfig (external) = Cp,eKaKc,e= -0.65 (1.0) (1.0) = -0.65

pext= (0.5 air) Vdes,2

CfigCdyn= (0.5)(1.2) (30.2)

2

(-0.65)(1.0) = -356 Pa = -0.36 kPapint= 0 kPaNet pressure across wall surface = -0.36 kPa (acting outwards)

As leeward wallwest wind direction:


2CfigCdyn= (0.5)(1.2) (31.7)

2(-0.3)(1.0) = -181 Pa = -0.18 kPa

pint= 0 kPa

Net pressure across wall surface = -0.18 kPa (ignore - side wall case governs)

West wall .

As windward wall (west wind direction):Cfig (external) = Cp,eKaKc,e= +0.7 (1.0) (0.9) = 0.63pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (31.7)

2(0.63)(1.0) = 380 Pa = 0.38 kPa


2CfigCdyn= (0.5)(1.2) (31.7)

2(-0.27)(1.0) = -163 Pa = -0.16 kPa


As side wallnorth wind direction:

For 0 to 1h (0 to 4.35 m) from north edge - same as east wall: -0.36 kPa.

For 1h to 2h (4.35m to 8.7m) from north edge of east wall :Cfig (external) = Cp,eKaKc,e= -0.5 (1.0) (1.0) = -0.5 pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.5)(1.0) = -274 Pa = -0.27 kPa

pint= 0 kPa


As side wallsouth wind direction:

For 0 to 1h (0 to 4.35 m) from south edge - same as east wall: -0.36 kPa.

South wall .

As windward wall (south wind direction):Cfig (external) = Cp,eKaKc,e= +0.7 (1.0) (0.9) = 0.63pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (30.2)

2(0.63)(1.0) = 345 Pa = 0.35 kPa


2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.27)(1.0) = -148 Pa = -0.15 kPa


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As leeward wall (north wind direction):


2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.3)(1.0) = -164 Pa = -0.16 kPa


This case governs except for following side wall cases.

As side wallwest wind direction:

For length 0 to 1h (0 to 4.35) m from west edge:


2CfigCdyn= (0.5)(1.2) (31.7)

2(-0.65)(1.0) = -392 Pa = -0.39 kPa

Cfig (internal) = 0.0 (1.0) = 0.0pint= 0 kPa


For length 1h to 2h (4.35 m to 8.7 m) from west edge:


2CfigCdyn= (0.5)(1.2) (31.7)

2(-0.5)(1.0) = -301 Pa = -0.30 kPa


For length 2h to 3h (8.7 m to 13.05 m) from west edge:Cfig (external) = Cp,eKaKc,e= -0.3 (1.0) (1.0) = -0.3 pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (31.7)

2(-0.3)(1.0) = -181 Pa = -0.18 kPa

pint= 0 kPa


As side walleast wind directionFor 0 to 4.35 m from east edge (i.e. gable end):Cfig (external) = Cp,eKaKc,e= -0.65 (1.0) (1.0) = -0.65pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.65)(1.0) = -356 Pa = -0.36 kPa

pint= 0 kPa


For 4.35 m to 8.7 m from east edge:


2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.5)(1.0) = -274 Pa = -0.27 kPa

pint= 0 kPa


Roof

north wind direction

north roof slope (surface 8).


2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.59)(1.0) = -323 Pa = -0.32 kPa

Cfig (internal) = 0.0 (1.0) = 0.0

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pint= 0 kPa

Net pressure across roof surface = -0.32-(0.0) = -0.32 kPa

South roof slope (surface 9) and hip end (surface 7).Cfig (external) = Cp,eKaKc,e= -0.5 (1.0) (1.0) = -0.5 pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.5)(1.0) = -274 Pa = -0.27 kPa

pint= 0 kPaNet pressure across roof surface = -0.27-(0.0) = -0.27 kPa

east wind direction

east roof slope (surface 10).


2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.59)(1.0) = -323 Pa = -0.32 kPa


Net pressure across roof surface = -0.32-(0.0) = -0.32 kPawest roof slope (surface 11).


2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.5)(1.0) = -274 Pa = -0.27 kPa


south wind directionsouth roof slope (surface 9).


2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.59)(1.0) = -323 Pa = -0.32 kPa


Net pressure across roof surface = -0.32-(0.0) = -0.32 kPanorth roof slope (surface 8) and hip end (surface 7).Cfig (external) = Cp,eKaKc,e= -0.5 (1.0) (1.0) = -0.5 pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.5)(1.0) = -274 Pa = -0.27 kPa

pint= 0 kPa

Net pressure across roof surface = -0.27-(0.0) = -0.27 kPacrosswind roof slopes (surfaces 10 and 11).

For length 0 to 1h (0 to 4.35 m) from windward edge:


pext= (0.5 air) Vdes,2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.9)(1.0) = -493 Pa = -0.49 kPa

pint= 0 kPa

Net pressure across roof surface = -0.49-(0.0) = -0.49 kPaFor length 1h to 2h (4.35m to 8.7m) from windward edge:



2(-0.5)(1.0) = -274 Pa = -0.27 kPa

pint= 0 kPa


For length 2h to 3h (8.7m to 13.05m) from windward edge:Cfig (external) = Cp,eKaKc,e= -0.3 (1.0) (1.0) = -0.3 (negative case)

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2(-0.3)(1.0) = -164 Pa = -0.16 kPa

pint= 0 kPa

Net pressure across roof surface = -0.16-(0.0) = -0.16 kPaCfig (external) = Cp,eKaKc,e= +0.1 (1.0) (0.9) = +0.09 (positive case)pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (30.2)

2(+0.09)(1.0) = +49 Pa = +0.05 kPa

Cfig (internal) = -0.3 (0.9) = -0.27pint= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.27)(1.0) = -148 Pa = -0.15 kPa

Net pressure across roof surface = +0.05-(-0.15) = +0.20 kPa

west wind direction

west roof slopes (surfaces 7 and 11).Cfig (external) = Cp,eKaKc,e= -0.59 (1.0) (1.0) = -0.59pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (31.7)

2(-0.59)(1.0) = -356 Pa = -0.36 kPa

pint= 0 kPa


crosswind roof slopes (surfaces 8 and 9).

For length 0 to 4.35 m from windward edge:Cfig (external) = Cp,eKaKc,e= -0.9 (1.0) (1.0) = -0.9


2(-0.9)(1.0) = -543 Pa = -0.54 kPa


For length 4.35 m to 8.7m from windward edge:



2(-0.5)(1.0) = -301 Pa = -0.30 kPa

pint= 0 kPa


For length 8.7 m to 13.05 m from windward edge:

Cfig (external) = Cp,eKaKc,e= -0.3 (1.0) (1.0) = -0.3 (negative case)pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (31.7)

2(-0.3)(1.0) = -181 Pa = -0.18 kPa

pint= 0 kPa

Net pressure across roof surface = -0.18-(0.0) = -0.18 kPaCfig (external) = Cp,eKaKc,e= +0.1 (1.0) (0.9) = +0.09 (positive case)pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (31.7)

2(+0.09)(1.0) = +54 Pa = +0.05 kPa

Cfig (internal) = -0.3 (0.9) = -0.27

pint= (0.5 air) Vdes,2CfigCdyn= (0.5)(1.2) (31.7)

2(-0.27)(1.0) = -163 Pa = -0.16 kPa

Net pressure across roof surface = +0.05-(-0.16) = +0.21 kPaFor length 13.05 m to 24 m from windward edge:

Cfig (external) = Cp,eKaKc,e= -0.2 (1.0) (1.0) = -0.2 (negative case)

pext= (0.5 air) Vdes,2CfigCdyn= (0.5)(1.2) (31.7)2(-0.2)(1.0) = -121 Pa = -0.12 kPapint= 0 kPa


Cfig (external) = Cp,eKaKc,e= +0.2 (1.0) (0.9) = +0.18 (positive case)pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (31.7)

2(+0.18)(1.0) = +109 Pa = +0.11 kPa

Cfig (internal) = -0.3 (0.9) = -0.27


2(-0.27)(1.0) = -163 Pa = -0.16 kPa

Net pressure across roof surface = +0.11-(-0.16) = +0.27 kPa

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east roof slopes (surface 10).


2CfigCdyn= (0.5)(1.2) (31.7)

2(-0.5)(1.0) = -301 Pa = -0.30 kPa

pint= 0 kPa


Note: under-eaves pressures are same as adjacent walls.

Design loadings ul timate limit states for foundations

Use roof pressures as above multiplied by 0.8 (Ka)

Design loadings for windows (ul timate limi t states)

(note: for permissible stress designdivide loads by 1.5)

For windows less than 1.44 m

2

in area on north, east and south walls:Cfig (external) = Cp,eKc,eK= +0.7 (1.0) (1.5) = +1.05 (positive case)pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (30.2)

2(+1.05)(1.0) = +575 Pa = +0.58 kPa

Cfig (internal) = Cp,iKc,i= -0.3 (1.0) = -0.3


2(-0.3)(1.0) = -164 Pa = -0.16 kPa

Net pressure across window = +0.58-(-0.16) = +0.74 kPa

For windows less than 1.44 m2

in area on west wall:

Cfig (external) = Cp,eKc,eK= +0.7 (1.0) (1.5) = +1.05 (positive case)pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (31.7)

2(+1.05)(1.0) = +633 Pa = +0.63 kPa


pint= (0.5 air) Vdes,2CfigCdyn= (0.5)(1.2) (31.7)2(-0.3)(1.0) = -181 Pa = -0.18 kPaNet pressure across window = +0.63-(-0.18) = +0.81 kPa

For windows less than 1.44 m2

in area on east and west walls within a distance of 1.2 m

(0.1d) from south and north corners, or on north or south wall within 1.2 m from eastcorners:

Cfig (external) = Cp,eKc,eK= -0.65 (1.0) (2.0) = -1.3 (negative case)pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (30.2)

2(-1.3)(1.0) = -711 Pa = -0.71 kPa

pint = 0 kPa

Net pressure across window = -0.71-(0.0) = -0.71 kPa

For windows less than 1.44 m2 in area on north and south walls within a distance of 1.2 mfrom west corners:


2CfigCdyn= (0.5)(1.2) (31.7)

2(-1.3)(1.0) = -784 Pa = -0.78 kPa

pint = 0 kPa


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For windows (or doors) more than 1.44 m2

in area on north, east and south walls:


2CfigCdyn= (0.5)(1.2) (30.2)

2(+0.7)(1.0) = +383 Pa = +0.38 kPa



2(-0.3)(1.0) = -164 Pa = -0.16 kPa


For windows (or doors) more than 1.44 m2

in area on west wall:


2CfigCdyn= (0.5)(1.2) (31.7)

2(+0.7)(1.0) = +422 Pa = +0.42 kPa



2(-0.3)(1.0) = -181 Pa = -0.18 kPa


For windows or doors up to 5.76 m2

in area on east and west walls within a distance of

2.4 m from south and north corners, or on north or south wall, within 2.4 m from east

corners:Cfig (external) = Cp,eKc,eK= -0.65 (1.0) (1.5) = -0.975 (negative case)pext= (0.5 air) Vdes,

2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.975)(1.0) = -534 Pa = -0.53 kPa

pint = 0 kPa


For windows or doors up to 5.76 m2in area on north and south walls within a distance of

2.4 m from west corners:


2CfigCdyn= (0.5)(1.2) (31.7)

2(-0.975)(1.0) = -588 Pa = -0.59 kPa

pint = 0 kPaNet pressure across window = -0.59-(0.0) = -0.59 kPa

Design loadings for roof cladding and battens (ul timate limit states)(note: for permissible stress designdivide loads by 1.5)

For roof cladding elements less than 1.44 m2in area, on roof surface 8, up to 1.2 m from

east edge of roof, and on roof surfaces 10 and 11, up to 1.2 m from south edge of roof:

Cfig (external) = Cp,eKc,eK= -0.9 (2.0) (2.0) = -1.8


2(-1.8)(1.0) = -985 Pa = -0.99 kPa

pint= 0 kPaNet pressure across element = -0.99-(0.0) = -0.99 kPa

For roof cladding elements less than 1.44 m2in area, on roof surfaces 8 and 9, up to 1.2 m

from west edge of roof :



2(-1.8)(1.0) = -1085 Pa = -1.09 kPa

pint = 0 kPa

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Net pressure across element = -1.09-(0.0) = -1.09 kPa


from the north west or south west corners of the roof :


pext= (0.5 air) Vdes,2

CfigCdyn= (0.5)(1.2) (31.7)2

(-2.7)(1.0) = -1628 Pa = -1.63 kPapint = 0 kPaNet pressure across element = -1.63-(0.0) = -1.63 kPa

For roof cladding elements less than 1.44 m2in area, on roof surfaces 10 and 11, up to 2.4

m from the cornerson the south side of the roof :


2CfigCdyn= (0.5)(1.2) (30.2)

2(-2.7)(1.0) = -1478 Pa = -1.48 kPa

pint= 0 kPa


For roof cladding elements less than 5.76 m2

in area, on roof surfaces 8 and 9, up to 2.4 mfrom east edge of roof, and on roof surfaces 10 and 11, up to 2.4 m from south edge of

roof:



2(-1.35)(1.0) = -739 Pa = -0.74 kPa

pint= 0 kPa



from west edge of roof :


pext= (0.5 air) Vdes,2CfigCdyn= (0.5)(1.2) (31.7)2(-1.35)(1.0) = -814 Pa = -0.81 kPapint = 0 kPa


For roof cladding elements less than 1.44 m2in area, on roof surfaces 8, 9,10 and 11, up

to 1.2 m from windward edge of roof :


2CfigCdyn= (0.5)(1.2) (30.2)

2(-1.18)(1.0) = -646 Pa = -0.65 kPa

pint= 0 kPa


For roof cladding elements less than 1.44 m2 in area, on roof surface 7, up to 1.2 m from

west edge of roof :


2CfigCdyn= (0.5)(1.2) (31.7)

2(-1.18)(1.0) = -711 Pa = -0.71 kPa

pint = 0 kPaNet pressure across element = -0.71-(0.0) = -0.71 kPa

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For roof cladding elements less than 5.76 m2in area, on roof surfaces 8, 9,10 and 11, up

to 2.4 m from windward edge of roof :


2CfigCdyn= (0.5)(1.2) (30.2)

2(-0.89)(1.0) = -487 Pa = -0.49 kPa

pint= 0 kPa


For roof cladding elements less than 5.76 m2in area, on roof surface 7, up to 2.4 m from

west edge of roof :



2(-0.89)(1.0) = -537 Pa = -0.54 kPa

pint = 0 kPa


Loading on battens should be applied as moving patch loads,with a tributary area equal

to the batten spacing times the truss rafter spacing, with the appropriate local pressure

factor for that area. For example, in this case, if the batten spacing is 0.6 m, the tributaryarea would be 1.2 0.6 = 0.72 m

2. Since this area is less than 0.25a

2, the local pressure

factor would be 1.0, 1.5, 2.0 or 3.0, depending on the distance of the centre of the patch

from the roof edges or corners. Over the remainder of the batten, Kshould be taken as

1.0; i.e. the loading should be the same as used for major structural members.

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Chapter 5.1r