CATALOGUE

PRODUCT CATALOGUE PURLINS & GIRTS 

ROOFING SOLUTIONS 

PRODUCT CATALOGUE 

PURLINS & GIRTS 

S&T029 

JAN 2013

Contents 

HST Channel Purlins & Girts 

General Information.........................................................................1 

Sag Rod and Bracing Channel Layout.......................................2 

Speed Channel Layout....................................................................2 

Standard Cleat Details & Hole Punching..............................3-4 

General Purpose Bracket Details.................................................3 

Section Geometry & Properties...................................................5 

Design Capacity Tables.............................................................6-11 

Design Information / Design Examples........................... 12-14 

HST Lapped Channel Purlins 

Introduction / Typical Construction Layout................... 15-16 

Design Capacity Tables.......................................................... 17-22 

Design Example...............................................................................23 

HST Tophat Purlins 

General Information.......................................................................24 

Sectional Properties / Typical Spans........................................25 

Design Capacity Tables / Dimensions............................... 26-29 

HST Purlin and Roof Selector 

Roof Selector Chart................................................................. 30-32 

HST Purlin Floor Joist Span Tables 

Floor Joist Span Tables................................... Inside Back Cover

hst purlins & girts 

Introduction 

HST Steel Purlins & Girts are high strength lipped profile 

sections, manufactured by Steel & Tube to provide an 

economic solution for your building project and to assist 

with design. 

Sections are supplied punched and cut to length as 

required. Accessories including speed channel, bracing, 

sag rods and fastenings are offered to provide a practical 

structural system. 

HST Tophat Sections 

Steel & Tube HST Tophat Sections are an economical and 

lightweight product for roof purlins, wall girts and floor 

joists. 

Description 

Steel & Tube’s galvanised cold formed steel HST Purlins 

& Girts, with accessories, make up part of a total system 

suitable to support a wide range of cladding materials, 

including profiled metal sheeting, sandwich panels and 

fibre cement sheeting. HST Purlin sections can also be 

readily adapted to a wide range of other application such 

as floor joists, ceiling support members and load bearing 

wall studs. 

Materials / Finish 

HST Purlins & Girts are rolled from galvanised high 

strength steel strip. 

Steel Thickness Grade Zinc Weight 

1.15 - 1.45 mm 500 (MPa) 275 gm/m 2 

1.75 - 2.0 mm 450 (MPa) 275 gm/m 2 

Purlin braces and accessories are formed from galvanised 

Grade 250 steel. 

Performance 

HST Purlin and Girt loads are presented in limit state 

format consistent with AS/NZS 1170:2002 “Structural 

Design Actions”. 

Load capacities have been determined in accordance 

with AISI “LRFD Cold-Formed Steel Design Manual”, 1991 

and confirmed by a full scale testing programme. 

AS/NZS4600:1996 has not been adopted, as the testing 

programme has demonstrated better correlation with the 

AISI reference above. The enclosed tables are generally 

conservative in relation to AS/NZS 4600:1996. 

Durability 

Provided HST Purlins, Girts and accessories are not 

exposed to moisture, service life will exceed 50 years, 

complying with the durability requirements of NZBC 

Approved Document B2. 

For applications within 1km of salt laden marine locations 

or severe industrial corrosive atmospheres, specialist 

advice should be sought. 

Length 

For ease of transportation and handling on site, the 

bundled length should be limited to 18 metres. Lengths 

exceeding 18 metres are subject to transport and 

handling facilities by special arrangement. 

Size Tolerances 

Web Depth ± 2 mm Flange Width ± 2 mm 

Lip ± 1 mm Hole Centres ± 1.5 mm 

Web / Flange Angle 88-93º 

Handling and Storage 

All sections and accessories must be kept dry during 

transport, stored on non-corrosive spacers above ground 

and covered to prevent moisture from entering between 

stacked sections. Should bundles become wet, they shall 

be broken open, dried with a cloth and restacked with 

separators to enable air to circulate. 

Bracing 

The HST Purlin & Girt system utilises standard brace / sag 

rod components or speed channel where required by the 

load tables. These shall be located in alternate bays, as 

shown on page 2, generally with a brace channel located 

immediately adjacent to both the eaves and ridge purlin. 

The galvanised HST brace channels are manufactured 

with end brackets custom fitted to suit the spacing. 

Standard sag rods are electro galvanised 12 mm diameter 

rod with double nuts and washers at each end. 16 mm 

diameter sag rods can be supplied to special order. All 

bracing components are fabricated from grade 250 (MPa) 

steel. 

Bracing should be located at the correct positions, as 

shown on page 2 to match pre-punched hole locations, 

otherwise lower load values may result. 

Load values with zero bracing have been included 

for the 100, 150 and 200 profiles, but generally it is 

recommended that at least one set of braces be provided, 

particularly when the HST Purlins will be used for access 

and temporary loading during construction.

Spacing 

hst purlins & girts 

Single bracing 

Sag Rod 

Purlin 

Bracing 

6 gap 

Sag Rod 

0.5L 

0.5L 

Purlin 

Bracing 

Channel 

Purlin 

bracing layout 

Roofing 

HST Purlin 

HST Purlin 

Sag Rod 

Brace Channel located 

adjacent eaves purlin 

Brace Channel to 

alternative bays 

Sag Rod 

speed channel 

NB. Brace length equal to purlin spacing less 3 mm 

bracing assembly 

adjustable cleat 

2mm End Cleat 

100 x 32 x 1.2 m 

Purlin 

Purlin 

Bracing 

Standard Speed 

Channel 

Speed Channel 

HST Purlin 

Adjustable Channel bracing 

Brace Channel

standard cleat 

details 

purlin cleats 

HST 100 

280 

f 

h 

140 

f 

h 

D 

dimensions 

purlin f g h 

HST 100 57 64 100 

HST 150 41 80 150 

HST 200 48 120 200 

HST 250 53 160 250 

HST 300 55 200 300 

HST 350 60 240 340 

HST 400 70 280 380 

g 

82 

g 

g 

HST 150, HST 200, HST 250, HST 300, HST 350, HST 400 

150 

80 

g 

h 

g 

h 

fastening to cleats 

f 

f 

82 

Cleats at internal supports 

Cleats at end supports 

6 - 10 

general purpose brackets 

Purlins 


Girts 

6 - 10 

c 

b 

2 mm 

18 φ mm 

holes 

5 mm Rod 

37 

d 

a 

35 35 

ultimate Joint 

shear Capacity 

dimensions 

purlin M12 bolts M16 bolts a b c d 

HST 150 23 33 130 80 112 65 

HST 200 26 40 130 120 155 75 

HST 250 28 44 150 160 195 85 

HST 300 30 50 150 200 250 95 

HST 350 30 50 180 240 290 105 

HST 400 30 50 180 280 330 115 

kN kN mm mm mm mm

standard hole 

location 

Single SPans 

HST 100 

0.5 L 

0.5 L 

64 

38 

38 64 76 

64 38 

= 

0.35 L 

One Sag Rod 

0.35 L 

= 

HST 100 

38 64 76 

76 

Two Sag Rods 


38 

0.5 L 0.5 L 

g 

One Brace 

HST 150 

0.35 L 0.35 L 

38 

Two Braces 

0.3 L 0.2 L 0.2 L 

0.3 L 

g 

Three Braces 

HST 200, HST 250, 

HST 300, HST 350, 

HST 400 

purlin 

dimensions 

g 

HST 100 64 

HST 150 80 

HST 200 120 

HST 250 160 

HST 300 200 

HST 350 240 

HST 400 280 

Hole Sizes 

Bolt Round Elongated 

M12 14 mm 14 x 18 mm 

M16 18 mm 18 x 22 mm 

Note 

All holes round unless specified otherwise. 

Purlins and Girts can be supplied with additional holes at other locations if required.

Section Geometry 

& Properties 

b 

x S 

x L 

b 

p 

d 

d 1 

x S 

b 1 

x L 

b 

d 3 

p 

d 

d 3 

d 1 

x S 

d 2 

x L 

b 1 

d 4 

q 

p 

d 

Profile I 

Section Geometry 

Profile II 

Profile III 

Profile Section MK d b t p q b 1 

d 1 

d 2 

d 3 

d 4 

x L 

x S 

Area A S 

Mass 

mm mm mm mm mm mm mm mm mm mm mm mm mm 2 kg/m 

I 100/12 102 51 1.15 15 18.0 24.5 255 2.04 

100/15 102 51 1.45 15 18.2 24.2 319 2.55 

100/19 102 51 1.85 15 18.4 23.7 404 3.26 

II 150/12 152 65 1.15 24 10 8 59 7 24.6 35.8 386 3.03 

150/15 152 65 1.45 24 10 8 59 7 24.7 35.9 483 3.79 

150/18 152 65 1.75 24 10 8 59 7 24.7 36.1 577 4.59 

III 200/12 203 75 1.15 25 12 8 59 10 10 48 26.2 39.0 479 3.79 

200/15 203 75 1.45 25 12 8 59 10 10 48 26.3 39.1 600 4.71 

200/18 203 75 1.75 25 12 8 59 10 10 48 26.3 39.2 719 5.64 

250/13 250 85 1.25 33 12 10 59 14 25 73 29.9 44.5 625 4.91 

250/15 250 85 1.45 33 12 10 59 14 25 73 30.0 44.6 723 5.68 

250/18 250 85 1.75 33 12 10 59 14 25 73 30.1 44.7 869 6.82 

300/15 300 100 1.45 38 12 10 59 64 25 123 34.0 51.4 854 6.70 

300/18 300 100 1.75 38 12 10 59 64 25 123 34.1 51.5 1027 8.06 

350/18 350 100 1.75 43 12 10 70 92 25 151 33.2 50.6 1132 8.97 

400/20 400 100 1.95 48 12 10 75 132 25 191 31.4 49.9 1375 10.91 

Notes 

1. A S 

= Gross Section Area 

2. All dimensions are normal within rolling tolerances 

Section Properties 

Section Area Weight Second Moment Section radius of Form Torsion Warping 

MK A S 

w t 

of Area Modulus gyration Factor Constant Factor 

mm 2 kN/m I x 

I y 

Z x 

Z y 

r x 

r y 

Q J I w 

0 6 mm 4 10 6 mm 4 10 3 mm 3 10 3 mm 3 mm mm mm 4 10 9 mm 6 

100/12 255 0.020 0.429 0.094 8.41 2.84 41.0 19.2 112 0.23 

100/15 319 0.025 0.533 0.116 10.45 3.52 40.9 19.0 224 0.28 

100/19 404 0.032 0.668 0.143 13.1 4.39 40.7 18.8 460 0.35 

150/12 386 0.030 1.38 0.249 18.2 6.17 59.8 25.4 0.734 170 1.67 

150/15 483 0.037 1.72 0.308 22.7 7.64 59.7 25.3 0.813 339 2.03 

150/18 577 0.045 2.06 0.365 27.0 9.06 59.6 25.1 0.872 590 2.37 

200/12 479 0.037 3.00 0.393 29.6 8.05 79.2 28.6 0.625 211 4.20 

200/15 600 0.046 3.75 0.488 37.0 10.0 79.1 28.5 0.697 420 5.16 

200/18 719 0.055 4.49 0.579 44.2 11.9 79.0 28.4 0.748 734 6.07 

250/13 625 0.048 5.86 0.657 46.9 11.9 96.8 32.4 0.572 326 11.0 

250/15 723 0.056 6.76 0.755 54.1 13.7 96.7 32.3 0.613 507 12.6 

250/18 869 0.067 8.10 0.897 64.8 16.3 96.5 32.1 0.653 887 14.8 

300/15 854 0.066 11.6 1.25 77.1 19.0 116 38.3 0.545 598 28.6 

300/18 1027 0.080 13.9 1.49 92.4 22.6 116 38.1 0.528 1050 33.8 

350/28 1132 0.088 20.2 1.66 115.7 24.6 133.7 38.3 0.561 1138 50.3 

400/20 1375 0.107 31.3 2.01 156.7 29.3 151.0 38.2 0.552 1739 78.4 

Notes 

1. All section properties are for the gross section 

2. Form factor based on F=300 MPa

design capacity 

tables 

ultimate Uniformly Distributed Load - single span 

HST 100/12 HST 100/15 HST 100/19 HST 150/12 HST 150/15 HST 150/18 

W LC 

W S 

W LC 

W S 

W LC 

W S 

W LC 

W S 

W LC 

W S 

W LC 

W S 

(kN/m) (kN/m) (kN/m) (kN/m) (kN/m) (kN/m) 

Span 0B 1B 2B FR DEF 0B 1B 2B FR DEF 0B 1B 2B FR DEF 0B 1B 2B FR DEF 0B 1B 2B FR DEF 0B 1B 2B FR DEF 

3.0 1.54 2.35 2.54 2.70 1.63 2.14 2.95 3.28 3.50 2.02 2.88 4.13 4.39 4.63 2.53 4.53 5.36 5.57 5.70 5.23 6.13 7.29 7.60 7.79 6.53 7.68 9.27 9.68 9.94 7.80 

3.5 0.94 1.63 1.82 1.98 1.02 1.23 2.07 2.35 2.57 1.27 1.66 2.91 3.17 3.40 1.59 2.99 3.84 4.06 4.19 3.30 4.02 5.23 5.53 5.72 4.11 5.04 6.63 7.05 7.30 4.91 

4.0 0.57 1.17 1.35 1.52 0.69 0.75 1.51 1.75 1.97 0.85 1.03 2.08 2.37 2.61 1.07 1.99 2.86 3.07 3.21 2.21 2.65 3.88 4.19 4.38 2.75 3.33 4.91 5.34 5.59 3.29 

4.5 0.37 0.85 1.04 1.20 0.48 0.49 1.12 1.30 1.55 0.60 0.68 1.51 1.82 2.06 0.75 1.30 2.19 2.40 2.53 1.55 1.74 2.96 3.27 3.46 1.93 2.15 3.73 4.16 4.42 2.31 

5.0 0.25 0.62 0.81 0.97 0.35 0.34 0.84 1.02 1.26 0.44 0.47 1.12 1.43 1.67 0.55 0.88 1.70 1.92 2.05 1.13 1.18 2.30 2.61 2.80 1.41 1.44 2.89 3.32 3.58 1.68 

5.5 0.18 0.45 0.64 0.80 0.26 0.24 0.62 0.82 1.04 0.33 0.34 0.82 1.13 1.38 0.41 0.62 1.34 1.56 1.70 0.85 0.82 1.81 2.12 2.32 1.06 1.00 2.27 2.69 2.96 1.27 

6.0 0.13 0.34 0.51 0.68 0.20 0.18 0.45 0.66 0.87 0.25 0.26 0.60 0.90 1.16 0.32 0.45 1.06 1.29 1.43 0.65 0.59 1.43 1.75 1.95 0.82 0.72 1.79 2.22 2.48 0.97 

6.5 0.26 0.41 0.58 0.16 0.34 0.54 0.75 0.20 0.45 0.73 0.99 0.25 0.34 0.85 1.08 1.21 0.51 0.43 1.14 1.47 1.66 0.64 0.54 1.43 1.85 2.12 0.77 

7.0 0.20 0.33 0.50 0.13 0.25 0.44 0.64 0.16 0.34 0.59 0.85 0.20 0.25 0.68 0.91 1.05 0.41 0.33 0.90 1.24 1.43 0.51 0.41 1.13 1.56 1.83 0.61 

7.5 0.15 0.27 0.43 0.10 0.20 0.36 0.56 0.13 0.27 0.48 0.74 0.16 0.54 0.78 0.91 0.34 0.25 0.72 1.05 1.25 0.42 0.32 0.90 1.32 1.59 0.50 

8.0 0.21 0.38 0.09 0.29 0.49 0.11 0.39 0.65 0.13 0.42 0.66 0.80 0.28 0.56 0.90 1.10 0.34 0.25 0.70 1.13 1.40 0.41 

8.5 0.34 0.57 0.71 0.23 0.45 0.77 0.97 0.29 0.55 0.97 1.24 0.34 

9.0 0.49 0.63 0.19 0.37 0.67 0.87 0.24 0.44 0.84 1.10 0.29 

9.5 0.43 0.57 0.16 0.58 0.78 0.21 0.36 0.72 0.99 0.25 

10.0 0.37 0.51 0.14 0.50 0.70 0.18 0.30 0.62 0.89 0.21 

10.5 0.43 0.64 0.15 0.54 0.81 0.18 

11.0 0.37 0.58 0.13 0.47 0.74 0.16 

11.5 0.41 0.68 0.14 

12.0 0.35 0.62 0.12 

12.5 

13.0 

13.5 

14.0 

14.5 

15.0 

15.5 

16.0 

16.5 

17.0 

17.5 

18.0 

Note: 

Tables assume one flange continuously restrained by roof or wall cladding.


HST 200/12 HST 200/15 HST 200/18 HST 250/13 HST 250/15 

W LC 

W S 

W LC 

W S 

W LC 

W S 

W LC 

W S 

W LC 

W S 

(kN/m) (kN/m) (kN/m) (kN/m) (kN/m) 

Span 0B 1B 2B FR DEF 0B 1B 2B FR DEF 0B 1B 2B FR DEF 1B 2B 3B FR DEF 1B 2B 3B FR DEF 

3.0 7.46 8.58 8.88 9.06 11.39 10.17 11.59 11.96 12.20 14.23 12.81 14.82 15.31 15.62 17.02 

3.5 5.05 6.18 6.47 6.66 7.17 6.88 8.35 8.73 8.96 8.96 8.63 10.66 11.17 11.48 10.72 

4.0 3.48 4.62 4.91 5.10 4.80 4.70 6.25 6.63 6.86 6.00 5.90 7.95 8.48 8.79 7.18 7.07 7.41 7.51 7.62 9.37 8.62 9.04 9.15 9.30 10.82 

4.5 2.39 3.55 3.84 4.03 3.37 3.20 4.81 5.19 5.42 4.22 4.02 6.10 6.63 6.94 5.04 5.47 5.81 5.91 6.02 6.58 6.67 7.08 7.20 7.35 7.60 

5.0 1.63 2.78 3.08 3.26 2.46 2.17 3.78 4.16 4.39 3.07 2.73 4.77 5.31 5.62 3.68 4.32 4.67 4.76 4.87 4.80 5.27 5.69 5.81 5.95 5.54 

5.5 1.15 2.21 2.51 2.70 1.85 1.53 3.01 3.39 3.63 2.31 1.90 3.79 4.33 4.65 2.76 3.48 3.82 3.92 4.03 3.61 4.23 4.65 4.77 4.92 4.16 

6.0 0.83 1.78 2.08 2.27 1.42 1.11 2.42 2.81 3.05 1.78 1.36 3.05 3.58 3.90 2.13 2.83 3.17 3.27 3.39 2.78 3.45 3.87 3.99 4.13 3.21 

6.5 0.62 1.44 1.74 1.93 1.12 0.82 1.96 2.36 2.60 1.40 1.00 2.46 3.00 3.33 1.67 2.33 2.67 2.77 2.88 2.18 2.83 3.26 3.38 3.52 2.52 

7.0 0.47 1.17 1.48 1.66 0.90 0.62 1.59 2.00 2.24 1.12 0.75 1.99 2.54 2.87 1.34 1.93 2.27 2.37 2.49 1.75 2.35 2.77 2.89 3.04 2.02 

7.5 0.37 0.96 1.26 1.45 0.73 0.47 1.29 1.71 1.95 0.91 0.58 1.61 2.17 2.50 1.09 1.61 1.95 2.05 2.17 1.42 1.95 2.38 2.50 2.65 1.64 

8.0 0.29 0.78 1.09 1.27 0.60 0.37 1.04 1.48 1.72 0.75 0.45 1.31 1.87 2.20 0.90 1.34 1.69 1.79 1.90 1.17 1.63 2.06 2.18 2.32 1.35 

8.5 0.63 0.94 1.13 0.50 0.29 0.84 1.28 1.52 0.63 0.36 1.05 1.61 1.95 0.75 1.12 1.47 1.57 1.69 0.98 1.35 1.79 1.91 2.06 1.13 

9.0 0.51 0.82 1.01 0.42 0.68 1.12 1.36 0.53 0.29 0.85 1.40 1.74 0.63 0.94 1.29 1.39 1.50 0.82 1.13 1.57 1.69 1.84 0.95 

9.5 0.42 0.71 0.90 0.36 0.55 0.97 1.22 0.45 0.69 1.22 1.56 0.54 0.78 1.13 1.23 1.35 0.70 0.93 1.38 1.50 1.65 0.81 

10.0 0.35 0.63 0.82 0.31 0.46 0.85 1.10 0.38 0.57 1.07 1.41 0.46 0.64 1.00 1.10 1.22 0.60 0.77 1.22 1.34 1.49 0.69 

10.5 0.55 0.74 0.27 0.38 0.75 1.00 0.33 0.47 0.94 1.28 0.40 0.54 0.89 0.99 1.11 0.52 0.64 1.08 1.20 1.35 0.60 

11.0 0.48 0.67 0.23 0.66 0.91 0.29 0.39 0.82 1.16 0.35 0.45 0.79 0.89 1.01 0.45 0.54 0.96 1.08 1.23 0.52 

11.5 0.43 0.62 0.20 0.57 0.83 0.25 0.72 1.06 0.30 0.38 0.70 0.80 0.92 0.39 0.46 0.86 0.98 1.13 0.46 

12.0 0.37 0.57 0.18 0.50 0.76 0.22 0.63 0.98 0.27 0.33 0.63 0.73 0.85 0.35 0.39 0.76 0.89 1.03 0.40 

12.5 0.44 0.70 0.20 0.55 0.90 0.24 0.56 0.66 0.78 0.31 0.34 0.68 0.81 0.95 0.35 

13.0 0.39 0.65 0.17 0.48 0.83 0.21 0.50 0.60 0.72 0.27 0.61 0.73 0.88 0.32 

13.5 0.42 0.77 0.19 0.45 0.55 0.67 0.24 0.54 0.67 0.82 0.28 

14.0 0.37 0.72 0.17 0.40 0.50 0.62 0.22 0.48 0.61 0.76 0.25 

14.5 0.46 0.58 0.20 0.43 0.56 0.71 0.23 

15.0 0.42 0.54 0.18 0.51 0.66 0.21 

15.5 0.47 0.62 0.19 

16.0 0.43 0.58 0.17 

16.5 

17.0 

17.5 

18.0 

Note: 



tables 



W LC 

W S 

W LC 

W S 

W LC 

W S 

W LC 

W S 

W LC 

W S 



3.0 

3.5 

4.0 11.00 11.58 11.74 11.92 12.96 

4.5 8.50 9.07 9.24 9.41 9.10 

5.0 6.70 7.28 7.45 7.63 6.64 7.44 7.82 7.93 8.06 9.47 9.50 10.07 10.22 10.41 11.36 11.73 12.32 12.49 12.69 16.58 14.78 15.34 15.50 15.69 25.67 

5.5 5.37 5.95 6.12 6.30 4.99 6.03 6.42 6.53 6.66 7.12 7.69 8.26 8.42 8.61 8.53 9.51 10.12 10.28 10.49 12.46 12.04 12.62 12.78 12.97 19.29 

6.0 4.36 4.94 5.11 5.30 3.84 4.95 5.36 5.47 5.60 5.48 6.31 6.88 7.04 7.23 6.57 7.81 8.44 8.61 8.81 9.60 9.95 10.55 10.71 10.90 14.86 

6.5 3.58 4.16 4.32 4.51 3.02 4.12 4.53 4.64 4.77 4.31 5.23 5.81 5.97 6.16 5.17 6.50 7.14 7.31 7.51 7.55 8.32 8.93 9.09 9.29 11.68 

7.0 2.95 3.53 3.70 3.89 2.42 3.45 3.87 3.98 4.11 3.45 4.38 4.97 5.12 5.31 4.14 5.45 6.10 6.27 6.47 6.04 7.03 7.65 7.81 8.01 9.36 

7.5 2.45 3.03 3.20 3.39 1.97 2.92 3.34 3.45 3.58 2.81 3.69 4.28 4.44 4.63 3.37 4.61 5.27 5.44 5.64 4.91 5.99 6.62 6.78 6.97 7.61 

8.0 2.04 2.62 2.79 2.98 1.62 2.48 2.91 3.02 3.15 2.31 3.13 3.71 3.88 4.07 2.77 3.92 4.58 4.75 4.96 4.05 5.13 5.78 5.94 6.13 6.27 

8.5 1.70 2.28 2.44 2.64 1.35 2.11 2.54 2.66 2.79 1.93 2.66 3.25 3.41 3.60 2.31 3.34 4.01 4.19 4.39 3.37 4.42 5.07 5.24 5.43 5.23 

9.0 1.41 1.99 2.16 2.35 1.14 1.81 2.24 2.36 2.49 1.62 2.27 2.86 3.02 3.21 1.95 2.86 3.53 3.71 3.92 2.84 3.80 4.48 4.65 4.84 4.40 

9.5 1.17 1.75 1.92 2.11 0.97 1.55 1.98 2.10 2.23 1.38 1.94 2.53 2.69 2.88 1.66 2.45 3.13 3.31 3.52 2.42 3.27 3.98 4.15 4.35 3.74 

10.0 0.96 1.54 1.71 1.91 0.83 1.32 1.76 1.88 2.02 1.18 1.66 2.24 2.41 2.60 1.42 2.10 2.78 2.97 3.17 2.07 2.82 3.55 3.73 3.92 3.21 

10.5 0.80 1.37 1.53 1.73 0.72 1.13 1.57 1.70 1.83 1.02 1.41 2.00 2.17 2.36 1.23 1.79 2.48 2.67 2.88 1.79 2.43 3.18 3.36 3.56 2.77 

11.0 0.68 1.21 1.38 1.58 0.62 0.96 1.41 1.53 1.67 0.89 1.20 1.79 1.96 2.15 1.07 1.52 2.23 2.42 2.62 1.56 2.09 2.86 3.05 3.24 2.41 

11.5 0.57 1.08 1.24 1.44 0.55 0.81 1.27 1.39 1.52 0.78 1.02 1.61 1.77 1.97 0.93 1.29 2.00 2.19 2.40 1.36 1.80 2.59 2.77 2.97 2.11 

12.0 0.49 0.96 1.13 1.32 0.48 0.69 1.14 1.26 1.40 0.69 0.87 1.44 1.61 1.81 0.82 1.10 1.80 1.99 2.20 1.20 1.54 2.34 2.53 2.72 1.86 

12.5 0.42 0.85 1.02 1.22 0.42 0.59 1.03 1.15 1.29 0.61 0.75 1.30 1.47 1.67 0.73 0.95 1.63 1.82 2.03 1.06 1.32 2.12 2.31 2.51 1.64 

13.0 0.36 0.76 0.93 1.13 0.38 0.51 0.93 1.05 1.19 0.54 0.64 1.18 1.34 1.54 0.65 0.82 1.47 1.66 1.88 0.94 1.14 1.93 2.12 2.32 1.46 

13.5 0.68 0.85 1.05 0.34 0.45 0.84 0.97 1.11 0.48 0.56 1.06 1.23 1.43 0.58 0.71 1.33 1.53 1.74 0.84 0.99 1.76 1.95 2.15 1.30 

14.0 0.61 0.77 0.97 0.30 0.39 0.76 0.89 1.03 0.43 0.49 0.96 1.13 1.33 0.52 0.62 1.21 1.40 1.62 0.76 0.86 1.60 1.80 2.00 1.17 

14.5 0.54 0.71 0.91 0.27 0.34 0.69 0.82 0.96 0.39 0.43 0.87 1.04 1.24 0.47 0.54 1.10 1.29 1.51 0.68 0.76 1.46 1.66 1.87 1.05 

15.0 0.48 0.65 0.85 0.25 0.63 0.75 0.90 0.35 0.38 0.79 0.96 1.16 0.42 0.48 1.00 1.19 1.41 0.61 0.67 1.33 1.54 1.74 0.95 

15.5 0.42 0.59 0.79 0.22 0.57 0.70 0.84 0.32 0.34 0.72 0.88 1.08 0.38 0.42 0.91 1.10 1.32 0.56 0.59 1.21 1.42 1.63 0.86 

16.0 0.54 0.74 0.20 0.52 0.65 0.79 0.29 0.65 0.82 1.02 0.35 0.38 0.82 1.02 1.24 0.51 0.52 1.10 1.32 1.53 0.78 

16.5 0.50 0.70 0.18 0.47 0.60 0.74 0.26 0.59 0.76 0.96 0.32 0.33 0.74 0.94 1.17 0.46 0.47 1.01 1.23 1.44 0.71 

17.0 0.46 0.66 0.17 0.42 0.55 0.70 0.24 0.53 0.70 0.90 0.29 0.67 0.88 1.10 0.42 0.92 1.15 1.36 0.65 

17.5 0.51 0.66 0.22 0.48 0.65 0.85 0.26 0.61 0.81 1.04 0.39 0.84 1.07 1.28 0.60 

18.0 0.48 0.62 0.20 0.43 0.60 0.80 0.24 0.55 0.76 0.98 0.36 0.76 1.00 1.21 0.55 

Note: 


ultimate axial Load - concentric 


φNC φN EX 

φNC φN EX 

φNC φN EX 

φNC φN EX 

φNC φN EX 

(kN) (kN) (kN) (kN) (kN) 

Span 0B 1B 2B Fr 0B 1B 2B Fr 0B 1B 2B Fr 0B 1B 2B Fr 0B 1B 2B FR 

3.0 30.2 67.7 75.9 81.6 257.3 37.8 93.1 105.3 113.4 321.0 45.3 118.3 134.6 146.0 383.2 45.6 86.1 92.4 96.4 559.8 60.1 116.6 125.4 131.2 699.6 

3.5 22.5 58.2 69.7 77.6 189.1 28.3 78.8 96.6 107.9 235.8 34.3 97.5 122.4 138.4 281.5 35.0 79.6 88.4 94.0 411.3 45.3 107.6 119.9 127.9 514.0 

4.0 17.5 48.1 62.3 72.9 144.7 22.1 63.3 85.1 101.3 180.5 27.0 75.4 107.7 129.5 215.6 27.7 71.7 83.8 91.3 314.9 35.1 96.9 113.4 123.9 393.5 

4.5 14.0 40.0 53.6 67.5 114.4 17.9 51.0 72.3 93.2 142.7 22.1 60.3 87.4 118.9 170.3 22.3 62.4 78.2 88.0 248.8 28.0 83.9 105.8 119.4 310.9 

5.0 11.5 33.2 45.9 61.2 92.6 14.9 41.8 60.1 83.9 115.6 18.5 49.5 71.2 106.5 138.0 18.2 52.9 71.8 84.3 201.5 23.0 70.9 97.1 114.3 251.9 

5.5 9.7 27.9 39.4 54.0 76.6 12.6 34.8 50.2 73.4 95.5 15.9 41.5 59.3 89.7 114.0 15.2 45.5 64.5 80.1 166.6 19.3 59.9 87.0 108.6 208.1 

6.0 8.3 23.6 33.7 47.6 64.3 10.9 29.4 42.5 63.0 80.2 13.7 35.2 50.2 75.6 95.8 12.9 39.2 56.5 75.3 140.0 16.5 51.3 76.1 102.1 174.9 

6.5 7.2 20.1 29.2 41.9 54.8 9.6 25.2 36.3 54.4 68.4 11.7 30.3 43.2 64.6 81.6 11.1 34.1 49.8 69.9 119.3 14.2 43.9 66.3 94.9 149.0 

7.0 6.4 17.4 25.2 36.9 47.3 8.5 21.9 31.4 47.1 59.0 10.0 26.4 37.4 55.9 70.4 9.7 29.9 44.3 64.0 102.8 12.3 38.0 58.1 86.8 128.5 

7.5 15.3 22.0 32.6 41.2 7.4 19.2 27.4 41.2 51.4 8.8 23.2 32.7 49.0 61.3 8.5 26.5 39.2 57.6 89.6 10.7 33.2 51.3 77.9 111.9 

8.0 13.5 19.4 29.0 36.2 17.0 24.1 36.2 45.1 7.7 20.6 28.8 43.3 53.9 7.6 23.4 35.0 52.0 78.7 9.4 29.3 45.1 69.9 98.4 

8.5 12.0 17.2 25.7 32.1 15.2 21.4 32.1 40.0 18.5 25.6 38.4 47.7 20.8 31.4 47.2 69.7 8.3 26.1 40.0 62.7 87.1 

9.0 15.3 22.9 28.6 13.6 19.2 28.6 35.7 16.7 23.0 34.2 42.6 18.6 28.4 43.0 62.2 23.4 35.8 56.6 77.7 

9.5 13.8 20.5 25.7 17.2 25.7 32.0 15.1 20.7 30.7 38.2 16.8 25.8 39.0 55.8 21.1 32.2 51.3 69.8 

10.0 12.5 18.5 23.2 15.6 23.2 28.9 13.8 18.7 27.7 34.5 15.2 23.3 35.6 50.4 19.2 29.1 46.3 63.0 

10.5 14.2 21.0 26.2 17.1 25.1 31.3 21.1 32.7 45.7 17.5 26.4 42.0 57.1 

11.0 13.0 19.1 23.9 15.6 22.9 28.5 19.3 30.0 41.6 24.1 38.3 52.0 

11.5 14.4 21.0 26.1 17.7 27.7 38.1 22.1 35.0 47.6 

12.0 13.3 19.2 24.0 16.3 25.7 35.0 20.4 32.1 43.7 

12.5 18.8 29.6 40.3 

13.0 17.4 27.4 37.3 

13.5 

14.0 

14.5 

15.0 

15.5 

16.0 

16.5 

17.0 

17.5 

18.0 

Note: 



tables 


HST 200/18 HST 250/13 HST 250/15 HST 250/18 

φNC φN EX 

φNC φN EX 

φNC φN EX 

φNC φN EX 

(kN) (kN) (kN) (kN) 

Span 0B 1B 2B Fr b b b Fr b b b Fr b b b FR 

3.0 72.9 149.9 161.8 169.5 836.8 

3.5 54.3 138.0 154.4 165.1 614.8 

4.0 42.3 122.3 145.8 160.0 470.7 105.4 115.3 117.4 121.5 614.3 127.6 140.0 142.7 147.8 709.2 160.9 178.0 181.5 188.5 849.6 

4.5 34.0 103.7 135.7 154.0 371.9 96.7 111.0 113.7 118.9 485.4 118.2 134.6 138.0 144.5 560.3 147.4 170.7 175.3 184.2 671.3 

5.0 28.1 86.5 122.8 147.3 301.2 86.8 106.0 109.4 115.9 393.2 106.0 128.3 132.7 140.8 453.9 132.3 162.1 168.2 179.3 543.7 

5.5 23.6 72.6 108.2 139.7 249.0 75.6 99.3 104.3 112.6 324.9 91.7 121.1 126.5 136.7 375.1 113.9 151.6 159.6 173.8 449.4 

6.0 19.9 61.3 93.4 130.8 209.2 65.8 91.8 97.9 109.0 273.0 78.7 112.4 119.6 132.2 315.2 97.7 140.2 149.6 167.8 377.6 

6.5 16.9 52.5 80.7 120.0 178.2 57.5 83.5 90.8 104.6 232.6 68.4 102.0 111.1 127.0 268.6 84.9 127.6 138.8 160.6 321.7 

7.0 14.6 45.5 70.1 108.3 153.7 50.5 74.5 82.9 99.3 200.6 60.0 90.3 101.3 121.3 231.6 74.5 112.3 126.8 152.3 277.4 

7.5 12.7 39.9 61.2 96.3 133.9 44.7 66.7 74.5 93.4 174.7 53.2 80.0 90.4 114.7 201.7 65.4 99.4 112.5 143.5 241.7 

8.0 11.2 35.3 53.9 85.8 117.7 40.0 60.0 67.2 87.1 153.6 47.5 71.4 80.7 106.8 177.3 57.6 88.7 100.3 133.9 212.4 

8.5 9.9 31.5 47.9 76.5 104.2 35.9 53.9 60.9 80.2 136.0 42.7 64.1 72.5 98.2 157.0 51.2 79.6 90.1 123.0 188.1 

9.0 8.8 28.3 42.8 68.4 93.0 32.5 48.7 55.0 73.2 121.4 38.4 58.0 65.5 88.9 140.1 45.9 71.9 81.4 111.1 167.8 

9.5 25.6 38.5 61.4 83.4 29.5 44.3 50.0 67.1 108.9 34.5 52.7 59.5 80.8 125.7 41.3 64.6 73.9 100.9 150.6 

10.0 23.3 34.8 55.4 75.3 27.0 40.5 45.7 61.7 98.3 31.3 48.1 54.3 73.8 113.5 37.5 58.4 66.9 92.1 135.9 

10.5 21.3 31.7 50.3 68.3 24.6 37.1 41.9 56.6 89.2 28.4 44.1 49.8 67.6 102.9 34.1 53.1 60.7 84.4 123.3 

11.0 19.5 29.0 45.8 62.2 22.5 34.2 38.6 52.2 81.2 26.0 40.6 45.9 62.3 93.8 31.2 48.4 55.4 77.6 112.3 

11.5 26.6 41.9 56.9 20.6 31.6 35.7 48.2 74.3 23.9 37.2 42.4 57.5 85.8 28.7 44.4 50.7 71.6 102.8 

12.0 24.5 38.5 52.3 19.0 29.3 33.1 44.7 68.3 22.0 34.2 39.1 53.3 78.8 26.5 40.8 46.6 65.8 94.4 

12.5 22.6 35.5 48.2 27.2 30.7 41.6 62.9 20.3 31.5 36.1 49.6 72.6 24.6 37.7 43.0 60.6 87.0 

13.0 21.0 32.8 44.6 25.3 28.7 38.8 58.2 29.2 33.4 46.2 67.1 22.8 34.9 39.8 56.0 80.4 

13.5 19.5 30.4 41.3 23.5 26.8 36.3 53.9 27.1 31.0 43.2 62.3 32.4 37.0 52.0 74.6 

14.0 18.2 28.3 38.4 21.9 25.0 34.0 50.2 25.2 28.8 40.4 57.9 30.2 34.4 48.3 69.4 

14.5 23.3 31.9 46.8 23.6 26.9 37.7 54.0 28.2 32.1 45.0 64.7 

15.0 21.8 30.0 43.7 25.1 35.2 50.4 26.4 30.0 42.1 60.4 

15.5 23.6 33.0 47.2 24.8 28.2 39.4 56.6 

16.0 22.1 30.9 44.3 26.5 37.0 53.1 

16.5 24.9 34.8 49.9 

17.0 23.5 32.8 47.0 

17.5 

18.0 

Note: 

Tables assume one flange continuously restrained by roof or wall cladding. 

10


HST 300/15 HST 300/18 HST 350/18 HST 400/20 

φNC φN EX 

φNC φN EX 

φNC φN EX 

φNC φN EX 

(kN) (kN) (kN) (kN) 

Span 1B 2B 3B Fr b b b Fr b b b Fr b b b FR 

3.0 

3.5 

4.0 

4.5 

5.0 122.1 136.9 140.1 146.1 775.9 156.7 177.6 181.9 190.0 930.6 169.9 189.2 193.0 199.7 1358.4 189.9 212.3 216.3 222.2 2103.2 

5.5 113.7 132.0 135.9 143.2 641.2 144.5 171.0 176.2 186.1 769.1 160.1 183.9 188.6 196.8 1122.6 180.4 207.8 212.7 219.9 1738.1 

6.0 104.4 126.5 131.2 140.0 538.8 131.1 163.3 169.9 181.8 646.2 149.1 178.1 183.8 193.5 943.3 169.7 202.9 208.8 217.4 1460.5 

6.5 93.8 120.4 126.0 136.4 459.1 116.9 154.4 162.6 177.1 550.6 136.8 171.5 178.4 190.0 803.8 157.6 197.5 204.5 214.7 1244.5 

7.0 84.0 113.8 120.3 132.5 395.9 104.9 144.7 154.3 172.0 474.8 122.9 164.4 172.4 186.2 693.0 142.7 191.7 199.9 211.7 1073.0 

7.5 76.1 106.5 114.2 128.4 344.8 95.3 134.3 145.4 166.4 413.6 110.0 156.6 166.0 182.0 603.7 127.4 185.3 194.8 208.5 934.7 

8.0 69.5 98.6 107.5 123.8 303.1 86.8 123.1 135.7 159.8 363.5 99.5 148.1 158.9 177.4 530.6 114.6 178.3 189.4 205.1 821.5 

8.5 62.6 90.0 100.2 119.0 268.5 78.1 112.4 125.4 152.7 322.0 90.7 139.0 151.4 172.4 470.0 103.9 170.8 183.5 201.4 727.7 

9.0 56.6 82.8 92.2 113.7 239.5 70.7 103.5 115.2 145.1 287.2 83.3 129.0 143.2 167.1 419.2 94.9 162.7 177.2 197.4 649.1 

9.5 51.5 76.6 85.0 108.1 214.9 64.3 96.0 106.4 137.1 257.8 77.1 118.3 134.4 161.5 376.3 87.2 153.2 170.4 193.2 582.6 

10.0 47.1 71.3 78.9 102.1 194.0 58.8 89.5 98.9 128.6 232.6 71.9 109.0 124.6 155.4 339.6 80.7 142.7 163.2 188.7 525.8 

10.5 43.3 65.8 73.7 95.5 175.9 53.5 82.1 92.5 119.7 211.0 65.9 101.1 115.2 149.0 308.0 75.1 131.8 154.8 184.0 476.9 

11.0 39.9 60.6 68.8 89.0 160.3 48.8 75.7 86.0 111.7 192.3 60.6 94.2 107.1 142.1 280.7 70.0 122.0 145.5 178.9 434.5 

11.5 36.9 56.1 63.7 83.3 146.7 44.8 70.0 79.5 104.6 175.9 55.7 88.1 99.9 134.8 256.8 65.6 113.5 135.7 173.6 397.6 

12.0 34.3 52.1 59.1 78.4 134.7 41.3 64.9 73.8 98.5 161.6 51.2 82.8 93.7 126.8 235.8 60.6 105.9 126.6 167.9 365.1 

12.5 31.8 48.5 55.0 74.0 124.1 38.1 60.4 68.7 93.1 148.9 47.2 78.1 88.1 118.7 217.3 55.8 99.2 118.4 162.0 336.5 

13.0 29.5 45.3 51.3 70.0 114.8 35.4 56.1 64.0 87.8 137.7 43.6 74.1 83.2 111.5 200.9 51.6 93.3 111.1 155.2 311.1 

13.5 27.4 42.4 48.1 65.5 106.4 32.9 52.1 59.9 82.2 127.7 40.5 70.0 78.8 105.1 186.3 47.9 88.0 104.6 147.7 288.5 

14.0 25.5 39.7 45.1 61.5 99.0 30.7 48.5 55.9 77.0 118.7 37.6 65.6 74.9 99.3 173.3 44.5 83.2 98.7 139.8 268.3 

14.5 23.8 37.3 42.4 57.8 92.3 28.7 45.3 52.1 72.4 110.7 35.1 61.7 71.4 94.1 161.5 41.5 78.9 93.5 131.9 250.1 

15.0 35.2 39.9 54.4 86.2 26.9 42.4 48.8 68.2 103.4 32.8 58.0 67.2 89.4 150.9 38.8 75.1 88.7 124.8 233.7 

15.5 33.2 37.7 51.4 80.7 25.3 39.7 45.7 64.3 96.8 30.7 54.4 63.4 85.2 141.3 36.3 71.5 84.4 118.2 218.9 

16.0 31.2 35.6 48.6 75.8 37.3 42.9 60.7 90.9 28.8 51.1 59.9 81.3 132.7 34.1 68.2 80.5 112.3 205.4 

16.5 29.4 33.7 46.0 71.2 35.1 40.4 57.4 85.5 27.1 48.1 56.6 77.8 124.7 32.0 65.2 77.0 106.8 193.1 

17.0 27.7 31.8 43.6 67.1 33.1 38.1 54.0 80.5 45.4 53.3 74.7 117.5 61.6 73.8 101.8 181.9 

17.5 30.1 41.4 63.3 31.3 35.9 51.0 76.0 42.9 50.4 71.8 110.9 58.1 70.6 97.2 171.7 

18.0 28.4 39.4 59.9 29.6 34.0 48.2 71.8 40.6 47.6 68.3 104.8 54.9 67.7 93.0 162.3 

Note: 

Tables assume one flange continuously restrained by roof or wall cladding. 

11

design information 

Design Capacity Tables 

The loads given in these tables are the design load 

capacity for ultimate limit state (W LC 

) in kilonewtons per 

metre of span (kN/m) for loads uniformly distributed 

along the span. For other load situations, specific 

design is required. Loads for intermediate spans may be 

determined by linear interpolation. 

Strength reduction factors are included in the design load 

capacity and have been determined from AISI “LRFD Cold- 

Formed Steel Design Manual” 1991 as follows: 

Bending φ = 0.9 

Axial Load φ = 0.85 

The self weight of HST purlin is not included in the load 

tables and should be calculated along with other dead 

loads. 

The tables are applicable to both inward and outward 

loads, ie. loads acting towards the centre of the section 

and away from the centre of the section respectively. 

In both cases the tables assume full lateral restraint is 

provided to one flange by roof or wall cladding, with 

normal screw fixings. For inward loads fully restrained 

values may be used, while for outward loads braced 

values are appropriate. 

Where HST purlins or girts are to be used in situations 

where at least one flange is not continuously laterally 

restrained by roof or wall cladding, then the design loads 

must be reduced. Specific guidance should be sought 

from Steel & Tube. 

The serviceability load (W S 

) is the uniformly distributed 

load (kN/m) at which the midspan deflection equals 

span/150. This corresponds to the serviceability limit 

recommended for roofs with brittle cladding under 

wind load only. Deflections at other loadings can be 

determined by direct proportion and corresponding 

serviceability limit states checked accordingly. 

load combinations 

The Limit State method of design is recommended with 

combinations of factored loads for each limit state in 

accordance with AS/NZS1170:2002. This should include 

dead, live, wind, snow and earthquake loads. 

For walls, provided the maximum spacing between 

brace struts / sag rods is limited to 3000 mm and the 

wall cladding is screw fixed to the girts, the dead load 

of the girts and cladding may be assumed to be carried 

directly by the bracing system. Accordingly, the girts may 

be designed for face loads only. The design engineer 

should ensure that the loads in the bracing system can be 

supported either by an eaves member or directly by the 

foundations. 

Axial Loads 

Where HST purlins are required to support axial loads, as 

well as bending loads, such as when they act as bracing 

struts or are required to transmit end wall loads to the 

roof bracing system, then the interaction equation set out 

below, as adopted from the AISI “LRFD Cold-Formed Steel 

Design Manual” 1991, is recommended. 

N* + C mx 

W L 

* ≤ 1.0 

φ N C 

W LC 

α nx 

N* = Applied ultimate limit state axial load (kN) 

φ N C 

= Design load capacity for members subject 

to axial compression (kN) 

W L 

* = Applied ultimate limit state uniformly 

distributed load about the X axis (kN/m) 

W LC 

= Design load capacity for uniformly 

distributed load (kN/m) 

C mx 

= Load coefficient 

= 1.0 for a member subject to uniformly 

distributed load 

α nx 

= (1 - N* /φ N EX 

) 

φ N EX 

= Euler buckling capacity about the X axis, 

as given by the design capacity axial load 

table (kN) 

Note the HST purlin is assumed to have zero distribution 

load about the Y axis of bending. Where biaxial bending 

occurs, then specific guidance should be sought from 

Steel & Tube. 

Loads are assumed to act about the major axis of 

symmetry. For roof pitches over 10º, the design engineer 

shall allow for the resultant force in the plane of the roof 

due to dead, live and snow loads. 

12

Design examples 

The following design examples are based on loads 

calculated in limit state format, in accordance with AS/ 

NZS 1170:2002 

Example 1 - Roof 

The example below considers a purlin in a typical portal 

frame building, with lightweight metal cladding. 

Limit State Loads from AS/NZS 1170:2002 

Dead Load G = 0.15 kPa 

Live Load Q = 0.25 kPa 

Ultimate Wind Load (W U 

) p z 

= 0.69 kPa 


) p z 

= 0.44 kPa 

Serviceability Wind (W S 

) p z 

= 0.46 kPa 


) p z 

= 0.29 kPa 

Geometry 

Span L = 9.0 m 

Purlin Spacing S = 1.9 m 

a) Check Serviceability Limit State (deflection) using W S 

values in Design Capacity Tables. 

Serviceability Load Combinations 

G + ψ l 

Q = 0.15 + 0 x 0.25 = 0.15 kPa 

W S 

= -0.46 kPa 

W S 

= 0.29 kPa 

calculate the maximum distributed loads 

W S 

* (wind) = 1.9 x 0.46 = 0.87 kN/m 

W S 

* (dead) = 1.9 x 0.15 = 0.29 kN/m 

Check wind load at deflection limit of L/150 

From charts for HST 250/15. 

W S 

= 0.95 kN/m > W L 

* HST 250/15 OK 

Check dead load at deflection limit of L/300 

W S 

= 0.5 x 0.95 

= 0.48 kN/m > W L 

* HST 250/15 OK 

b) Check Ultimate Limit State using W LC 

values in Design 

Capacity Tables. 

Ultimate Load Combinations 

1.35G = 1.35 x 0.15 = 0.20 kPa 

1.2G + 1.5Q = 1.2 x 0.15 + 1.5 x 0.25 = 0.56 kPa 

1.2G + W U 

= 1.2 x 0.15 + 0.44 = 0.62 kPa 

0.9G + W U 

= 0.9 x 0.15 - 0.69 = 0.56 kPa 

Calculate the maximum distributed loads 

W L 

* = 1.9 x 0.62 = 1.18 kN/m 

W L 

* = 1.9 x -0.56 = -1.06 kN/m 

Top flange of the purlin is restrained by the sheeting 

material, therefore consider the purlin fully restrained for 

downward loading. 

W LC (FR) 

= 1.84 kN/m > W L 

* HST 250/15 OK 

For upward loading, use braced case with one 

brace 

W LC(1B) 

= 1.13 kN/m > W L 

* HST 250/15 OK 

Use HST 250/15 at 1.9 m spacing, with 1 brace at 

midspan. 

Example 2 - Wall 

The example below considers a girt in a typical portal 


Limit State Loads from AS/NZS1170:2002 


) p z 

(in) = 0.86 kPa 


) p z 

(out) = 0.43 kPa 


) p z 

(in) = 0.57 kPa 


) p z 

(out) = 0.28 kPa 

Geometry 

Span L = 10.0 m 

Girt Spacing S = 1.8 m 




W S 

(in) = 0.57 kPa (in) 

W S 

(out) = 0.28 kPa (out) 


W S 

* (wind) = 1.8 x 0.57 = 1.03 kN/m (in) 

check wind load at deflection limit of L/150 

From charts for HST 300/15 

W S 

= 1.18 kN/m > W L 

*(in) HST 300/15 OK 




Calculate the maximum ultimate limit state 

distributed loads 

W L 

*(in) = 1.8 x 0.86 = 1.55 kN/m (in) 

W L 

*(out) = 1.8 x 0.43 = 0.77 kN/m (out) 

Outer flange of the girt is restrained by the 

sheeting material, therefore the girt is considered 

fully restrained for inward loading. 

W LC(FR) 

= 2.02 kN/m > W L 

*(in) HST 300/15 OK 

For outward loading, use braced case with one 

brace. 

W LC(1B) 

= 1.32 kN/m > W L 

*(in) HST 300/15 OK 

Use HST 300/15 at 1.8 m spacing, with 1 brace at 

midspan. 

13

Design examples 

Example 3 - axial 

Consider the purlin of example 1 as a roof bracing strut, 

with an ultimate axial load N* due to longitudinal wind. 

Design Axial Load N* = 34.0 kN 

From example 1 W L 

* = 1.18 kN/m 

From example 1 W L 

* = -1.06 kN/m 

Check Ultimate Limit State using values in Design 


a) Try HST 250/15 with 3 braces 

From Design Capacity Tables 

Design axial load capacity φN C 

= 65.5 kN 

Euler buckling capacity φN EX 

= 140.1 kN 

Design load capacity W LC(FR) 

= 1.84 kN/m 

Design load capacity W LC(3B) 

= 1.69 kN/m 

C mx 

= 1.0 

α nx 

= 1 - N*/φ N EX 

= 1 - 34.0 / 140.1 = 0.757 

N* 

φ N C 

+ 

C mx 

W L 

* 

W LC(FR) 

α nx 

b) Try two HST 250/15 (with 1 brace), purlins back to 

back. 

Ultimate loads to purlins 

N* = 17.0 kN (per purlin) 

W L 

* = 0.59 kN/m (per purlin) 

W L 

* = -0.53 kN/m (per purlin) 

From Design Capacity Tables 

Design axial load capacity φN C 

= 38.4 kN 

Euler buckling capacity φN EX 

= 140.1 kN 

Design load capacity W LC(FR) 

= 1.84 kN/m 

Design load capacity W LC(1B) 

= 1.13 kN/m 

C mx 

= 1.0 

α nx 

= 1 - N*/φ N EX 

= 1 - 17.0 / 140.1 = 0.879 

N* 

φ N C 

+ 

C mx 

W L 

* 

W LC(FR) 

α nx 

= 17.0 1.0 x 0.59 

+ 

38.4 1.84 x 0.879 

= 0.81 < 1.0 2HST 250/15 OK 

N* 

φ N C 

= 34.0 1.0 x 1.18 

+ 

65.5 1.84 x 0.757 

= 1.37 > 1.0 No Good 

+ 

C mx 

W L 

* 

W LC(3B) 

α nx 

= 34.0 1.0 x 1.06 

+ 

65.5 1.69 x 0.757 

= 1.35 > 1.0 No Good 

N* 

φ N C 

+ 

C mx 

W L 

* 

W LC(1B) 

α nx 

= 17.0 1.0 x 0.53 

+ 

65.5 1.13 x 0.879 

= 0.98 < 1.0 2HST 250/15 OK 

Use two HST 250/15 back to back (with 1 brace), for 

the purlins acting as roof bracing struts. 

14

lapped Purlins 

introduction 

HST Lapped Purlins 

Lapped HST purlins provide the advantage of increased 

load carrying capacity and reduced deflections when 

compared to single span HST purlins. The following tables 

replace the Uniformly Distributed Load Single Span tables 

on pages 6, 7 and 8 of the design guide, when lapped 

HST purlins are used. For all other properties refer to the 

design guide. 

The tables are based on a lap length of 5% of span length 

(and a minimum length of 300 mm) each side of the 

support. 

Design cApacity tables 

Load capacities have been determined in accordance 

with AISI “LRFD Cold-Formed Steel Design manual”, 1991 

and confirmed by a full scale testing programme. 

The loads given in these tables are the design load 

capacity for ultimate limit state (W LC 

) in kilonewtons per 

metre of span (kN/m) for loads uniformly distributed 

along the span. For other load situations, specific 

design is required. Loads for intermediate spans may be 

determined by linear interpolation. 

The self weight of the HST purlin is not included in the 

load tables and should be calculated along with other 

dead loads. 

Tables are included for end spans and internal spans. 

A greater load capacity is available for internal spans 

because of the continuity at both ends. 

Because the maximum moment for the end span occurs 

over the first support, the internal HST purlin is required 

to carry the same moment and the load tables are not 

applicable. Consequently the purlin size and number 

of braces for the first internal purlin or girt must be at 

least equal to the end purlin requirements. Refer to 

the diagram below. 

The tables are applicable to both inward and outward 

loads. In both cases the tables assume full lateral restraint 

is provided to one flange by roof or wall cladding, with 

normal screw fixings. Contrary to single span HST purlins, 

braced values must be used for both inward and outward 

loads. Fully restrained values are not applicable for lapped 

HST purlins unless the compression flange is continuously 

fully restrained (note the compression flange changes 

from one flange to the other within the span). 

Where HST purlins or girts are to be used in situations 

where at least one flange is not continuously laterally 

restrained by roof or wall cladding, then the design loads 

must be reduced. Specific guidance should be sought 

from Steel & Tube. 

The serviceability load (W S 

) is the uniformly distributed 

load (kN/m) at which the midspan deflection equals span/ 

150. 

Limitations 

The Tables are not applicable when the length of adjacent 

spans differ by more than 10%, nor when the loading 

varies by more than 50% between adjacent spans. 

The tabulated values are for end and internal spans 

where there is a lap over each internal support. They are 

not applicable when a HST purlin is continuous over a 

support without a lap. Purlin spacing is limited to 2.4 

metres when the standard bracing channel is used. 

Specific guidance should be sought from Steel & Tube 

when these requirements are not satisfied. 

Use end span tables 

Use internal span tables 

Use end span tables 

Purlin/Girt lap over each 

internal support 

Purlin/Girt size and 

bracing as end span 

Purlin/Girt size and 

bracing as end span 

15

HST Lapped purlins 

with Single bracing 

Sag Rod 

typical construction 

layout 

Purlin 

Bracing 

Sag Rod 

0.5L 

Gable End 

Rafter 

Spacing 

0.5L 

Purlin 

Bracing 

Channel 

Purlin 

L 

0.05 L < 300 0.05 L < 300 

Lapped Purlins - End Span 

L 

0.05 L < 300 0.05 L < 300 

0.05 L < 300 0.05 L < 300 

Lapped Purlins - Internal Span 

Hole positions for intermediate braces as for the single span purlins 

Cleat welded to rafter 

Spacers same thickness as cleat 

Note: Minimum bolt size M16 for lapped purlins 

16


tables 

ultimate Uniformly distributed load - lapped end span 


W LC 

W S 

W LC 

W S 

W LC 

W S 

W LC 

W S 

W LC 

W S 



3.0 6.43 6.43 6.43 10.22 8.72 8.72 8.72 12.75 11.00 11.00 11.00 15.23 9.50 9.50 9.50 22.24 12.68 12.68 12.68 27.80 

3.5 4.80 4.85 4.85 6.44 6.53 6.58 6.58 8.03 8.28 8.32 8.32 9.59 7.27 7.27 7.27 14.01 9.72 9.72 9.72 17.51 

4.0 3.57 3.77 3.77 4.31 4.86 5.13 5.13 5.38 6.14 6.50 6.50 6.42 5.73 5.73 5.73 9.38 7.67 7.67 7.67 11.73 

4.5 2.73 3.00 3.02 3.03 3.70 4.09 4.11 3.78 4.66 5.20 5.21 4.51 4.43 4.62 4.62 6.59 6.01 6.19 6.19 8.24 

5.0 2.13 2.40 2.47 2.21 2.88 3.26 3.36 2.75 3.61 4.15 4.27 3.29 3.47 3.80 3.80 4.80 4.72 5.10 5.10 6.00 

5.5 1.67 1.95 2.05 1.66 2.26 2.66 2.80 2.07 2.83 3.37 3.55 2.47 2.76 3.14 3.18 3.61 3.77 4.24 4.26 4.51 

6.0 1.33 1.61 1.73 1.28 1.79 2.19 2.36 1.59 2.24 2.78 3.00 1.90 2.22 2.60 2.69 2.78 3.03 3.52 3.62 3.47 

6.5 1.06 1.35 1.48 1.01 1.42 1.83 2.02 1.25 1.78 2.31 2.57 1.50 1.80 2.18 2.31 2.19 2.45 2.95 3.10 2.73 

7.0 0.85 1.14 1.28 0.80 1.13 1.55 1.75 1.00 1.42 1.95 2.23 1.20 1.47 1.85 2.00 1.75 1.99 2.50 2.69 2.19 

7.5 0.67 0.97 1.12 0.65 0.89 1.32 1.53 0.82 1.12 1.65 1.95 0.97 1.19 1.58 1.75 1.42 1.61 2.14 2.36 1.78 

8.0 0.53 0.83 0.99 0.54 0.71 1.13 1.35 0.67 0.87 1.41 1.71 0.80 0.97 1.36 1.55 1.17 1.30 1.85 2.08 1.47 

8.5 0.42 0.72 0.88 0.45 0.56 0.97 1.19 0.56 0.69 1.21 1.52 0.67 0.79 1.18 1.38 0.98 1.05 1.60 1.85 1.22 

9.0 0.34 0.62 0.78 0.38 0.46 0.83 1.07 0.47 0.56 1.04 1.36 0.56 0.64 1.02 1.23 0.82 0.85 1.39 1.65 1.03 

9.5 0.28 0.54 0.70 0.32 0.37 0.72 0.96 0.40 0.45 0.90 1.22 0.48 0.52 0.89 1.11 0.70 0.69 1.22 1.49 0.88 

10.0 0.23 0.46 0.64 0.28 0.31 0.62 0.87 0.34 0.37 0.78 1.10 0.41 0.43 0.78 1.00 0.60 0.57 1.07 1.35 0.75 

10.5 0.25 0.54 0.79 0.30 0.31 0.68 1.00 0.36 0.36 0.69 0.91 0.52 0.48 0.93 1.22 0.65 

11.0 0.21 0.47 0.72 0.26 0.26 0.59 0.91 0.31 0.30 0.60 0.83 0.45 0.40 0.82 1.12 0.56 

11.5 0.22 0.51 0.84 0.27 0.26 0.53 0.76 0.39 0.34 0.72 1.02 0.49 

12.0 0.19 0.44 0.77 0.24 0.22 0.47 0.70 0.35 0.29 0.63 0.94 0.43 

12.5 0.25 0.55 0.87 0.38 

13.0 0.21 0.48 0.80 0.34 

13.5 

14.0 

14.5 

15.0 

15.5 

16.0 

16.5 

17.0 

17.5 

18.0 

Note: 

1. Use this table only for external spans with a lap at one end. 

2. Lap length to be the greater of 5% of the longer adjacent span or 300 mm each side of the support. 

3. Tables assume one flange continuously restrained by roof or wall cladding 

17


tables 


hst 200/18 HST 250/13 HST 250/15 HST 250/18 

W LC 

W S 

W LC 

W S 

W LC 

W S 

W LC 

W S 

(kN/m) (kN/m) (kN/m) (kN/m) 

Span 0B 1B 2B FR DEF 1B 2B 3B FR DEF 1B 2B 3B FR DEF 1B 2B 3B FR DEF 

3.0 15.95 15.95 15.95 33.25 

3.5 12.27 12.27 12.27 20.94 

4.0 9.71 9.71 9.71 14.03 8.35 8.35 8.35 8.35 18.31 10.06 10.06 10.06 10.06 21.13 12.68 12.68 12.68 12.68 25.32 

4.5 7.62 7.85 7.85 9.85 6.76 6.76 6.76 6.76 12.86 8.17 8.17 8.17 8.17 14.84 10.32 10.32 10.32 10.32 17.78 

5.0 5.97 6.47 6.47 7.18 5.41 5.58 5.58 5.58 9.37 6.59 6.75 6.75 6.75 10.82 8.38 8.55 8.55 8.55 12.96 

5.5 4.74 5.41 5.42 5.40 4.35 4.68 4.68 4.68 7.04 5.29 5.67 5.67 5.67 8.13 6.72 7.19 7.19 7.19 9.74 

6.0 3.81 4.48 4.60 4.16 3.54 3.97 3.98 3.98 5.42 4.31 4.82 4.82 4.82 6.26 5.46 6.12 6.12 6.12 7.50 

6.5 3.07 3.75 3.95 3.27 2.91 3.34 3.42 3.42 4.27 3.54 4.07 4.15 4.15 4.92 4.47 5.20 5.27 5.27 5.90 

7.0 2.49 3.18 3.43 2.62 2.41 2.84 2.97 2.97 3.42 2.93 3.46 3.60 3.60 3.94 3.69 4.42 4.59 4.59 4.72 

7.5 2.02 2.71 3.01 2.13 2.01 2.44 2.56 2.60 2.78 2.44 2.97 3.13 3.16 3.21 3.06 3.79 4.00 4.02 3.84 

8.0 1.63 2.33 2.65 1.75 1.68 2.11 2.24 2.30 2.29 2.04 2.57 2.72 2.79 2.64 2.55 3.27 3.48 3.56 3.16 

8.5 1.31 2.02 2.36 1.46 1.40 1.84 1.96 2.04 1.91 1.69 2.24 2.39 2.48 2.20 2.12 2.85 3.06 3.17 2.64 

9.0 1.06 1.75 2.11 1.23 1.17 1.61 1.74 1.83 1.61 1.41 1.96 2.11 2.22 1.86 1.76 2.49 2.70 2.84 2.22 

9.5 0.87 1.53 1.90 1.05 0.97 1.42 1.54 1.64 1.37 1.16 1.73 1.88 2.00 1.58 1.46 2.19 2.40 2.56 1.89 

10.0 0.71 1.34 1.72 0.90 0.80 1.25 1.38 1.49 1.17 0.96 1.53 1.68 1.81 1.35 1.20 1.93 2.14 2.31 1.62 

10.5 0.59 1.17 1.56 0.78 0.67 1.11 1.24 1.35 1.01 0.80 1.35 1.50 1.65 1.17 1.00 1.71 1.91 2.10 1.40 

11.0 0.49 1.03 1.43 0.67 0.56 0.99 1.11 1.23 0.88 0.67 1.20 1.35 1.50 1.02 0.85 1.51 1.72 1.92 1.22 

11.5 0.41 0.90 1.31 0.59 0.48 0.88 1.00 1.13 0.77 0.57 1.07 1.22 1.38 0.89 0.72 1.35 1.55 1.76 1.07 

12.0 0.35 0.79 1.20 0.52 0.41 0.79 0.91 1.04 0.68 0.49 0.95 1.11 1.27 0.78 0.61 1.20 1.41 1.62 0.94 

12.5 0.30 0.69 1.11 0.46 0.35 0.70 0.83 0.96 0.60 0.42 0.85 1.01 1.17 0.69 0.53 1.07 1.28 1.50 0.83 

13.0 0.26 0.61 1.03 0.41 0.30 0.63 0.75 0.89 0.53 0.36 0.76 0.92 1.08 0.62 0.45 0.95 1.16 1.39 0.74 

13.5 0.22 0.53 0.95 0.36 0.26 0.56 0.69 0.83 0.48 0.32 0.68 0.84 1.01 0.55 0.39 0.85 1.06 1.29 0.66 

14.0 0.19 0.46 0.89 0.33 0.23 0.50 0.63 0.77 0.43 0.28 0.60 0.77 0.94 0.49 0.34 0.76 0.97 1.20 0.59 

14.5 0.20 0.45 0.58 0.72 0.38 0.24 0.54 0.70 0.87 0.44 0.30 0.67 0.88 1.12 0.53 

15.0 0.18 0.40 0.53 0.67 0.35 0.21 0.48 0.64 0.82 0.40 0.26 0.60 0.81 1.05 0.48 

15.5 0.19 0.42 0.59 0.77 0.36 0.23 0.53 0.74 0.98 0.44 

16.0 0.17 0.38 0.54 0.72 0.33 0.20 0.47 0.68 0.92 0.40 

16.5 0.18 0.42 0.62 0.87 0.36 

17.0 0.16 0.38 0.57 0.82 0.33 

17.5 

18.0 

Note: 




18


hst 300/15 HST 300/18 HST 350/18 HST 400/20 

W LC 

W S 

W LC 

W S 

W LC 

W S 

W LC 

W S 



3.0 

3.5 

4.0 

4.5 

5.0 8.86 8.86 8.86 8.86 18.50 11.24 11.24 11.24 11.24 22.19 13.63 13.63 13.63 13.63 32.38 16.95 16.95 16.95 16.95 50.14 

5.5 7.47 7.47 7.47 7.47 13.90 9.50 9.50 9.50 9.50 16.67 11.53 11.53 11.53 11.53 24.33 14.33 14.33 14.33 14.33 37.67 

6.0 6.19 6.38 6.38 6.38 10.70 7.89 8.13 8.13 8.13 12.84 9.77 9.87 9.87 9.87 18.74 12.26 12.26 12.26 12.26 29.02 

6.5 5.15 5.50 5.50 5.50 8.42 6.54 7.03 7.03 7.03 10.10 8.12 8.53 8.53 8.53 14.74 10.40 10.59 10.59 10.59 22.82 

7.0 4.32 4.79 4.79 4.79 6.74 5.48 6.13 6.13 6.13 8.09 6.82 7.45 7.45 7.45 11.80 8.79 9.24 9.24 9.24 18.27 

7.5 3.65 4.18 4.21 4.21 5.48 4.62 5.35 5.39 5.39 6.57 5.76 6.55 6.55 6.55 9.60 7.48 8.13 8.13 8.13 14.86 

8.0 3.10 3.63 3.73 3.73 4.52 3.91 4.64 4.78 4.78 5.42 4.90 5.73 5.81 5.81 7.91 6.42 7.20 7.20 7.20 12.24 

8.5 2.64 3.18 3.32 3.32 3.77 3.33 4.06 4.26 4.26 4.52 4.18 5.02 5.18 5.18 6.59 5.52 6.34 6.42 6.42 10.21 

9.0 2.26 2.80 2.94 2.98 3.17 2.84 3.57 3.78 3.82 3.80 3.58 4.42 4.64 4.65 5.55 4.75 5.60 5.76 5.76 8.60 

9.5 1.93 2.48 2.63 2.68 2.70 2.42 3.16 3.37 3.45 3.23 3.07 3.91 4.14 4.19 4.72 4.09 4.97 5.19 5.20 7.31 

10.0 1.65 2.20 2.35 2.43 2.31 2.07 2.80 3.01 3.12 2.77 2.62 3.48 3.71 3.80 4.05 3.52 4.44 4.66 4.71 6.27 

10.5 1.41 1.97 2.12 2.21 2.00 1.76 2.50 2.71 2.84 2.40 2.24 3.11 3.34 3.46 3.50 3.04 3.98 4.21 4.29 5.41 

11.0 1.20 1.76 1.92 2.02 1.74 1.50 2.24 2.45 2.60 2.08 1.90 2.78 3.02 3.16 3.04 2.62 3.58 3.81 3.92 4.71 

11.5 1.01 1.58 1.74 1.85 1.52 1.27 2.01 2.22 2.39 1.82 1.62 2.50 2.74 2.90 2.66 2.25 3.23 3.46 3.59 4.12 

12.0 0.86 1.43 1.58 1.71 1.34 1.08 1.81 2.01 2.20 1.60 1.38 2.25 2.49 2.67 2.34 1.93 2.93 3.16 3.31 3.63 

12.5 0.74 1.29 1.44 1.58 1.18 0.93 1.63 1.84 2.03 1.42 1.18 2.03 2.27 2.47 2.07 1.65 2.66 2.89 3.06 3.21 

13.0 0.64 1.16 1.32 1.46 1.05 0.81 1.47 1.68 1.88 1.26 1.02 1.84 2.08 2.29 1.84 1.43 2.42 2.65 2.83 2.85 

13.5 0.56 1.05 1.21 1.36 0.94 0.70 1.33 1.54 1.75 1.13 0.89 1.67 1.91 2.12 1.65 1.24 2.20 2.44 2.63 2.55 

14.0 0.49 0.96 1.11 1.26 0.84 0.61 1.20 1.41 1.63 1.01 0.77 1.51 1.75 1.98 1.48 1.08 2.00 2.24 2.45 2.28 

14.5 0.43 0.87 1.02 1.18 0.76 0.54 1.09 1.30 1.52 0.91 0.68 1.37 1.62 1.85 1.33 0.95 1.82 2.07 2.29 2.06 

15.0 0.38 0.79 0.94 1.10 0.69 0.47 0.99 1.20 1.42 0.82 0.60 1.25 1.49 1.73 1.20 0.83 1.66 1.92 2.14 1.86 

15.5 0.33 0.71 0.87 1.03 0.62 0.42 0.89 1.11 1.33 0.74 0.53 1.13 1.38 1.62 1.09 0.74 1.51 1.78 2.01 1.68 

16.0 0.30 0.65 0.81 0.97 0.56 0.37 0.81 1.02 1.25 0.68 0.47 1.03 1.27 1.52 0.99 0.65 1.38 1.65 1.88 1.53 

16.5 0.26 0.59 0.75 0.91 0.51 0.33 0.73 0.95 1.18 0.62 0.42 0.93 1.18 1.43 0.90 0.58 1.26 1.54 1.77 1.40 

17.0 0.24 0.53 0.69 0.86 0.47 0.30 0.66 0.88 1.11 0.56 0.37 0.84 1.10 1.35 0.82 0.52 1.15 1.43 1.67 1.28 

17.5 0.21 0.48 0.64 0.81 0.43 0.27 0.60 0.81 1.05 0.52 0.34 0.76 1.02 1.28 0.76 0.47 1.04 1.33 1.58 1.17 

18.0 0.19 0.43 0.60 0.77 0.40 0.24 0.54 0.75 0.99 0.48 0.30 0.69 0.94 1.21 0.69 0.42 0.95 1.25 1.49 1.07 

Note: 




19


tables 

ultimate uniformly distributed load - INTERNAL SPAN 


W LC 

W S 

W LC 

W S 

W LC 

W S 

W LC 

W S 

W LC 

W S 



3.0 9.65 9.65 9.65 23.00 13.09 13.09 13.09 28.70 16.53 16.53 16.53 34.26 14.34 14.34 14.34 50.05 19.15 19.15 19.15 62.55 

3.5 7.26 7.26 7.26 14.49 9.86 9.86 9.86 18.07 12.48 12.48 12.48 21.57 10.94 10.94 10.94 31.52 14.64 14.64 14.64 39.39 

4.0 5.56 5.64 5.64 9.71 7.57 7.67 7.67 12.11 9.61 9.73 9.73 14.45 8.60 8.60 8.60 21.12 11.52 11.52 11.52 26.39 

4.5 4.31 4.49 4.51 6.82 5.86 6.12 6.13 8.50 7.42 7.79 7.79 10.15 6.92 6.92 6.92 14.83 9.28 9.28 9.28 18.53 

5.0 3.41 3.60 3.68 4.97 4.63 4.90 5.01 6.20 5.86 6.23 6.37 7.40 5.50 5.68 5.68 10.81 7.45 7.63 7.63 13.51 

5.5 2.75 2.94 3.06 3.73 3.73 3.99 4.17 4.66 4.70 5.07 5.30 5.56 4.45 4.71 4.75 8.12 6.03 6.36 6.37 10.15 

6.0 2.24 2.43 2.58 2.88 3.04 3.31 3.52 3.59 3.82 4.19 4.48 4.28 3.65 3.91 4.02 6.26 4.95 5.28 5.40 7.82 

6.5 1.84 2.04 2.21 2.26 2.50 2.77 3.01 2.82 3.14 3.50 3.83 3.37 3.02 3.28 3.45 4.92 4.11 4.44 4.63 6.15 

7.0 1.53 1.73 1.91 1.81 2.07 2.34 2.60 2.26 2.60 2.96 3.32 2.70 2.53 2.79 2.99 3.94 3.44 3.78 4.02 4.92 

7.5 1.28 1.47 1.67 1.47 1.72 2.00 2.27 1.84 2.16 2.52 2.90 2.19 2.12 2.39 2.61 3.20 2.90 3.24 3.51 4.00 

8.0 1.07 1.27 1.47 1.21 1.44 1.72 2.00 1.51 1.81 2.16 2.55 1.81 1.80 2.06 2.31 2.64 2.45 2.80 3.10 3.30 

8.5 0.89 1.10 1.30 1.01 1.20 1.49 1.78 1.26 1.51 1.86 2.26 1.51 1.52 1.79 2.05 2.20 2.07 2.43 2.75 2.75 

9.0 0.75 0.95 1.16 0.85 1.00 1.29 1.59 1.06 1.26 1.62 2.02 1.27 1.30 1.56 1.83 1.85 1.76 2.13 2.46 2.32 

9.5 0.62 0.83 1.05 0.72 0.83 1.12 1.43 0.90 1.06 1.40 1.82 1.08 1.10 1.37 1.65 1.58 1.49 1.87 2.22 1.97 

10.0 0.52 0.73 0.94 0.62 0.69 0.98 1.29 0.77 0.87 1.22 1.64 0.93 0.94 1.21 1.49 1.35 1.26 1.65 2.00 1.69 

10.5 0.58 0.85 1.17 0.67 0.72 1.07 1.49 0.80 0.79 1.07 1.35 1.17 1.06 1.45 1.82 1.46 

11.0 0.49 0.75 1.07 0.58 0.61 0.94 1.36 0.69 0.67 0.94 1.23 1.02 0.89 1.28 1.66 1.27 

11.5 0.51 0.82 1.25 0.61 0.57 0.83 1.13 0.89 0.76 1.13 1.52 1.11 

12.0 0.44 0.72 1.14 0.54 0.49 0.74 1.04 0.78 0.65 1.00 1.40 0.98 

12.5 

13.0 

13.5 

14.0 

14.5 

15.0 

15.5 

16.0 

16.5 

17.0 

17.5 

18.0 

Note: 

1. Use this table only for internal spans (excluding the first internal span) with laps at both ends. 

2. Do not use this table for first internal span. Use purlin size and number of braces as end span. 



20


hst 200/18 HST 250/13 HST 250/15 HST 250/18 

W LC 

W S 

W LC 

W S 

W LC 

W S 

W LC 

W S 



3.0 24.13 24.13 24.13 74.81 

3.5 18.50 18.50 18.50 47.11 

4.0 14.59 14.59 14.59 31.56 12.56 12.56 12.56 12.56 41.19 15.15 15.15 15.15 15.15 47.55 19.11 19.11 19.11 19.11 56.97 

4.5 11.78 11.78 11.78 22.17 10.15 10.15 10.15 10.15 28.93 12.27 12.27 12.27 12.27 33.40 15.52 15.52 15.52 15.52 40.01 

5.0 9.48 9.69 9.69 16.16 8.36 8.36 8.36 8.36 21.09 10.13 10.13 10.13 10.13 24.35 12.83 12.83 12.83 12.83 29.17 

5.5 7.66 8.11 8.11 12.14 6.85 7.00 7.00 7.00 15.85 8.35 8.49 8.49 8.49 18.29 10.64 10.77 10.77 10.77 21.91 

6.0 6.27 6.74 6.88 9.35 5.65 5.94 5.94 5.94 12.21 6.88 7.21 7.21 7.21 14.09 8.77 9.17 9.17 9.17 16.88 

6.5 5.19 5.66 5.91 7.35 4.72 5.02 5.10 5.10 9.60 5.75 6.12 6.20 6.20 11.08 7.30 7.81 7.89 7.89 13.28 

7.0 4.34 4.80 5.12 5.89 3.98 4.28 4.41 4.43 7.69 4.84 5.21 5.38 5.38 8.87 6.15 6.65 6.85 6.85 10.63 

7.5 3.65 4.11 4.48 4.79 3.38 3.68 3.81 3.88 6.25 4.11 4.49 4.65 4.72 7.21 5.21 5.72 5.95 6.01 8.64 

8.0 3.08 3.55 3.96 3.94 2.89 3.19 3.33 3.42 5.15 3.52 3.89 4.05 4.16 5.94 4.45 4.95 5.18 5.31 7.12 

8.5 2.60 3.08 3.52 3.29 2.48 2.79 2.92 3.04 4.29 3.02 3.39 3.56 3.70 4.96 3.81 4.32 4.55 4.73 5.94 

9.0 2.21 2.68 3.15 2.77 2.14 2.45 2.58 2.72 3.62 2.61 2.98 3.15 3.31 4.17 3.28 3.79 4.01 4.23 5.00 

9.5 1.87 2.35 2.83 2.36 1.85 2.16 2.29 2.45 3.07 2.25 2.63 2.80 2.98 3.55 2.83 3.34 3.56 3.81 4.25 

10.0 1.59 2.07 2.56 2.02 1.61 1.91 2.05 2.22 2.64 1.95 2.33 2.50 2.70 3.04 2.45 2.95 3.18 3.45 3.65 

10.5 1.34 1.82 2.33 1.74 1.39 1.70 1.84 2.01 2.28 1.69 2.07 2.24 2.45 2.63 2.12 2.62 2.85 3.13 3.15 

11.0 1.13 1.61 2.12 1.52 1.21 1.52 1.65 1.84 1.98 1.46 1.85 2.02 2.24 2.29 1.83 2.34 2.56 2.86 2.74 

11.5 0.96 1.42 1.94 1.33 1.05 1.36 1.49 1.68 1.73 1.26 1.65 1.82 2.05 2.00 1.58 2.09 2.31 2.62 2.40 

12.0 0.82 1.26 1.79 1.17 0.90 1.22 1.35 1.55 1.53 1.08 1.48 1.65 1.89 1.76 1.36 1.87 2.09 2.41 2.11 

12.5 0.70 1.11 1.65 1.03 0.78 1.09 1.23 1.43 1.35 0.93 1.33 1.50 1.74 1.56 1.17 1.67 1.90 2.23 1.87 

13.0 0.60 0.98 1.53 0.92 0.67 0.98 1.12 1.32 1.20 0.80 1.20 1.36 1.61 1.39 1.01 1.50 1.73 2.06 1.66 

13.5 0.52 0.87 1.42 0.82 0.58 0.88 1.02 1.23 1.07 0.70 1.08 1.25 1.50 1.24 0.88 1.35 1.57 1.91 1.48 

14.0 0.45 0.77 1.32 0.74 0.51 0.80 0.94 1.14 0.96 0.61 0.97 1.14 1.39 1.11 0.77 1.21 1.44 1.78 1.33 

14.5 0.45 0.72 0.86 1.07 0.86 0.54 0.87 1.04 1.30 1.00 0.68 1.09 1.31 1.66 1.20 

15.0 0.39 0.65 0.79 1.00 0.78 0.47 0.78 0.96 1.22 0.90 0.60 0.97 1.20 1.55 1.08 

15.5 0.42 0.70 0.88 1.14 0.82 0.53 0.87 1.10 1.46 0.98 

16.0 0.37 0.62 0.81 1.07 0.74 0.47 0.78 1.01 1.37 0.89 

16.5 0.42 0.70 0.93 1.29 0.81 

17.0 0.38 0.63 0.85 1.21 0.74 

17.5 

18.0 

Note: 





21


tables 


hst 300/15 HST 300/18 HST 350/18 HST 400/20 

W LC 

W S 

W LC 

W S 

W LC 

W S 

W LC 

W S 



3.0 

3.5 

4.0 

4.5 

5.0 13.32 13.32 13.32 13.32 41.62 16.93 16.93 16.93 16.93 49.92 20.53 20.53 20.53 20.53 72.86 25.53 25.53 25.53 25.53 112.81 

5.5 11.21 11.21 11.21 11.21 31.27 14.29 14.29 14.29 14.29 37.50 17.33 17.33 17.33 17.33 54.74 21.54 21.54 21.54 21.54 84.76 

6.0 9.56 9.56 9.56 9.56 24.09 12.20 12.20 12.20 12.20 28.89 14.81 14.81 14.81 14.81 42.17 18.40 18.40 18.40 18.40 65.29 

6.5 8.13 8.24 8.24 8.24 18.94 10.39 10.53 10.53 10.53 22.72 12.79 12.79 12.79 12.79 33.17 15.88 15.88 15.88 15.88 51.35 

7.0 6.90 7.17 7.17 7.17 15.17 8.80 9.18 9.18 9.18 18.19 10.88 11.15 11.15 11.15 26.55 13.79 13.84 13.84 13.84 41.11 

7.5 5.90 6.27 6.30 6.30 12.33 7.52 8.04 8.07 8.07 14.79 9.32 9.80 9.80 9.80 21.59 11.85 12.16 12.16 12.16 33.43 

8.0 5.09 5.46 5.57 5.57 10.16 6.48 6.99 7.14 7.14 12.19 8.03 8.61 8.68 8.68 17.79 10.27 10.76 10.76 10.76 27.54 

8.5 4.41 4.79 4.94 4.96 8.47 5.61 6.12 6.35 6.36 10.16 6.97 7.55 7.74 7.74 14.83 8.96 9.52 9.59 9.59 22.96 

9.0 3.85 4.23 4.38 4.44 7.14 4.88 5.40 5.62 5.71 8.56 6.08 6.66 6.90 6.94 12.49 7.85 8.42 8.60 8.60 19.34 

9.5 3.37 3.75 3.91 4.00 6.07 4.27 4.78 5.01 5.14 7.28 5.32 5.91 6.16 6.26 10.62 6.92 7.49 7.73 7.75 16.45 

10.0 2.96 3.34 3.50 3.63 5.20 3.74 4.25 4.48 4.66 6.24 4.68 5.27 5.52 5.67 9.11 6.13 6.69 6.94 7.02 14.10 

10.5 2.61 2.99 3.15 3.30 4.49 3.29 3.80 4.03 4.24 5.39 4.12 4.71 4.97 5.16 7.87 5.44 6.01 6.26 6.39 12.18 

11.0 2.30 2.68 2.85 3.01 3.91 2.90 3.41 3.64 3.88 4.69 3.64 4.23 4.49 4.72 6.84 4.82 5.42 5.67 5.84 10.59 

11.5 2.03 2.42 2.58 2.76 3.42 2.55 3.07 3.30 3.55 4.10 3.22 3.81 4.07 4.33 5.99 4.28 4.90 5.15 5.36 9.27 

12.0 1.80 2.18 2.35 2.54 3.01 2.25 2.77 3.00 3.27 3.61 2.85 3.45 3.71 3.98 5.27 3.80 4.44 4.70 4.93 8.16 

12.5 1.59 1.98 2.14 2.35 2.66 1.99 2.50 2.73 3.02 3.19 2.52 3.12 3.38 3.68 4.66 3.38 4.04 4.30 4.55 7.22 

13.0 1.40 1.79 1.96 2.17 2.37 1.75 2.27 2.50 2.80 2.84 2.22 2.83 3.10 3.41 4.15 3.00 3.69 3.94 4.22 6.42 

13.5 1.23 1.63 1.80 2.02 2.11 1.54 2.06 2.29 2.60 2.54 1.96 2.58 2.84 3.16 3.70 2.67 3.37 3.62 3.92 5.73 

14.0 1.08 1.48 1.65 1.88 1.90 1.36 1.87 2.10 2.42 2.27 1.72 2.35 2.61 2.95 3.32 2.37 3.09 3.34 3.65 5.14 

14.5 0.95 1.35 1.52 1.75 1.71 1.19 1.70 1.93 2.26 2.05 1.51 2.14 2.40 2.75 2.99 2.11 2.82 3.09 3.40 4.63 

15.0 0.84 1.23 1.40 1.64 1.54 1.05 1.55 1.78 2.11 1.85 1.33 1.95 2.22 2.57 2.70 1.86 2.59 2.86 3.18 4.18 

15.5 0.74 1.13 1.30 1.54 1.40 0.93 1.41 1.64 1.98 1.68 1.18 1.78 2.05 2.41 2.45 1.65 2.37 2.65 2.99 3.79 

16.0 0.66 1.03 1.20 1.44 1.27 0.83 1.29 1.52 1.86 1.52 1.05 1.63 1.90 2.27 2.22 1.46 2.17 2.46 2.80 3.44 

16.5 0.59 0.94 1.11 1.36 1.16 0.74 1.18 1.41 1.75 1.39 0.93 1.49 1.76 2.13 2.03 1.30 1.99 2.29 2.64 3.14 

17.0 0.52 0.86 1.03 1.28 1.06 0.66 1.07 1.30 1.65 1.27 0.84 1.36 1.63 2.01 1.85 1.17 1.82 2.13 2.49 2.87 

17.5 0.47 0.78 0.96 1.21 0.97 0.59 0.98 1.21 1.56 1.16 0.75 1.24 1.51 1.90 1.70 1.05 1.67 1.99 2.35 2.63 

18.0 0.42 0.71 0.89 1.14 0.89 0.54 0.89 1.12 1.47 1.07 0.68 1.13 1.41 1.80 1.56 0.94 1.53 1.85 2.22 2.42 

Note: 





22

Design Example 

The following design examples are based on loads 

calculated in limit state format, in accordance with AS/ 

NZS 1170:2002 

Lapped purlin Example - Roof 

The example below considers a purlin in a 6-bay portal 


Limit State Loads 

Dead Load G = 0.15 kPa 

Live Load Q = 0.25 kPa 

Ultimate Wind Load End Bay (W U-E 

) p z 

= 0.91 kPa 

Ultimate Wind Load End Bay (W U-E 

) p z 

= 0.44 kPa 

Ultimate Wind Load Intl Bay (W U-I 

) p z 

= 0.69 kPa 

Ultimate Wind Load Intl Bay (W U-I 

) p z 

= 0.44 kPa 

Serviceability Wind (W S-E 

) p z 

= 0.59 kPa 

Serviceability Wind (W S-E 

) p z 

= 0.29 kPa 

Serviceability Wind (W S-I 

) p z 

= 0.45 kPa 

Serviceability Wind (W S-I 

) p z 

= 0.29 kPa 

Geometry 

Span L = 10.0 m 

Purlin Spacing S = 2.4 m 



i) End Span 


G + ψ l 

Q = 0.15 + 0 x 0.25 = 0.15 kPa 

W S-E 

= -0.59 kPa 

W S-E 

= 0.29 kPa 


W S-E 

* (dead) = 2.4 x 0.15 = 0.36 kN/m 

W S-E 

* (wind) = 2.4 x 0.59 = 1.42 kN/m 

check wind load at deflection limit of L/150. From 

charts for HST 250/18, lapped end span 

W S 

= 1.62 kN/m > W S-E 

* HST 250/18 OK 

check dead load at deflection limit of L/300 

W S 

= 0.5 x 1.62 

= 0.81 kN/m > W S-E 

* HST 250/18 OK 

ii) Central Internal Spans 


G + ψ l 

Q = 0.15 + 0 x 0.25 = 0.15 kPa 

W S-I 

= -0.45 kPa 

W S-I 

= 0.29 kPa 


W S-I 

* (dead) = 2.4 x 0.15 = 0.36 kN/m 

W S-I 

* (wind) = 2.4 x 0.59 = 1.42 kN/m 

check wind load at deflection limit of L/150. From 

charts for HST 250/13, lapped internal span 

W S 

= 2.64 kN/m > W S-I 

* HST 250/13 OK 

check dead load at deflection limit of L/300. 

W S 

= 0.5 x 2.64 

= 1.32 kN/m > W S-I 

* HST 250/13 OK 




i) End Span 


1.35G = 1.35 x 0.15 = 0.20 kPa 

1.2G + 1.5Q = 1.2 x 0.15 + 1.5 x 0.25 = 0.56 kPa 

1.2G + W U-E 

= 1.2 x 0.15 + 0.44 = 0.62 kPa 

0.9G + W U-E 

= 0.9 x 0.15 - 0.91 = -0.78 kPa 

As the flange in compression varies along the span 

from top to bottom, the fully restrained case (FR) is not 

applicable, and hence no distinction is made between 

upward and downward loading. Therefore calculating 

the maximum distributed load. 

W L-E 

* = 2.4 x -0.78 = -1.87 kN/m 

Considering the purlin with two braces: 

W LC(2B) 

= 2.64 kN/m > W L-E 

* HST 250/18 OK 

Use HST 250/18 at 2.4 m spacing, with 2 braces for 

the end span and the first internal spans (those 

adjacent to the end span). 

ii) Central Internal Spans 


1.35G = 1.35 x 0.15 = 0.20 kPa 

1.2G + 1.5Q = 1.2 x 0.15 + 1.5 x 0.25 = 0.56 kPa 

1.2G + W U-I 

= 1.2 x 0.15 + 0.44 = 0.62 kPa 

0.9G + W U-I 

= 0.9 x 0.15 - 0.69 = -0.56 kPa 

Calculating the maximum distributed load: 

W L-I 

* = 2.4 x 0.62 = -1.49 kN/m 

Considering the purlin with one brace: 

W LC(1B) 

= 1.61 kN/m > W L-I 

* HST 250/13 OK 

Use HST 250/13 at 2.4 m spacing, with 1 brace for 

the central internal spans. 

Note 

If simply supported purlins had been used, the end spans would have been HST 300/18 

(2 braces) and the internal spans would have been HST 300/15 (2 braces). 

23

HST tophats 

introduction 

A Great NEW Product 

Steel & Tube HST Tophat sections are an economical, 

lightweight, versatile and easy to use product for roof 

purlins, wall girts, floor joists, and hundreds of other 

applications such as fencing, carports, racking etc. 

Generally, for spans from 3m to 7m, HST Tophat purlins 

will provide an economical alternative to timber and Cee 

section purlins. 

Tophat purlins are easy to use, being fastened directly to 

their supports, results in a saving on cleats. The symmetrical 

section means no braces or nogs are required to prevent 

twisting and the profile is easily lapped for optimal 

performance. 

Durability 

HST Tophat purlins are manufactured from hot dipped 

galvanised steel with a coating weight of 275gram/sqm, 

in line with other common lightweight steel structural 

building products. 

This gives good protection in most exposed internal 

environments, for and external use in moderate marine 

environments. Where used in a lined exterior dwelling a 

thermal break should be provided between the Tophat and 

the cladding to avoid thermal bridging. Where sections are 

exposed to salt spray but not rain washing, maintenance 

is required to remove any build up of salt deposits on the 

surface. 

Run off from, or contact with, materials which are 

incompatible with zinc should be avoided. 

Handling and Storage 

HST Tophat sections must be kept dry during storage as 

water present between close stacked sections will cause 

premature corrosion. If they become wet they should be 

separated and stacked openly to allow for ventilation to dry 

the surface. 

Lengths 

HST Tophat sections are available in long run lengths up 

to 12 metres, depending on the available transport and 

handling facilities. Stock lengths may be available from 

your local stockist. 

Cutting 

Cutting is preferably done by shear or hacksaw. When using 

abrasive disc blades care must be taken to ensure the swarf 

produced does not affect other materials and the burred 

edge should be cleaned off at the completion of cutting. 

Minimum lap (between fasteners) 

= 15% of TopHat span 

24

HST tophats 

Design capacity tables 

hst tophat sectional properties 

Tophat Section Thickness Area Mass per Second Moment Centre of Section Modulus Radius of Shear Torsion Warping Monounit 

Area (Full) Gravity (Full) gyration Centre Constant Constant Symmetry 

length 

constant 

t(BMT) l x l y y c z x z y r x r y y e J l w ß x 

mm mm 2 kg/m 10 6 mm 4 10 6 mm 4 mm 10 3 mm 3 10 3 mm 3 mm mm mm mm 4 109mm 6 mm 

60 HST Tophat 0.75 BMT 0.75 150 1.18 0.078 0.119 31.7 2.45 2.20 22.8 28.1 44.2 28.2 16.05 110 

60 HST Tophat 0.95 BMT 0.95 190 1.50 0.098 0.151 31.7 3.09 2.78 22.8 28.1 44.2 57.3 20.33 110 

100 HST Tophat 0.75 BMT 0.75 248 1.93 0.338 0.439 55.2 6.3 5.39 37.1 42.2 67.4 46.5 238.61 158 

100 HST Tophat 0.95 BMT 0.95 314 2.45 0.428 0.556 55.2 7.75 6.83 37.0 42.2 67.4 94.5 302.24 158 

120 HST Tophat 0.75 BMT 0.75 278 2.17 0.527 0.519 65.6 8.03 6.13 43.7 43.3 82.3 52.1 363.31 184 

120 HST Tophat 0.95 BMT 0.95 352 2.75 0.667 0.657 65.6 10.16 7.76 43.6 43.3 82.3 105.9 460.20 184 

150 HST Tophat 0.95 BMT 0.95 410 3.21 1.16 0.878 81.1 14.30 9.60 53.3 46.3 103.9 123.5 758.37 225 

150 HST Tophat 1.15 BMT 1.15 497 3.88 1.40 1.06 81.1 17.30 11.62 53.2 46.3 103.9 219.1 918.02 225 

typical hst tophat purlin spans (mm) 

Purlin Region region 2 

S spacings Urban rural secondary Use urban rural secondary Use 

(mm) Simple Lapped Simple Lapped Simple Lapped Simple Lapped Simple Lapped Simple Lapped 

60 HST Tophat 0.75 BMT 1200 2200 2800 2000 2600 2600 3200 2100 2700 1900 2500 2500 3200 

800 1800 2400 1700 2300 2100 2700 1800 2300 1700 2200 1900 2500 

60 HST Tophat 0.95 BMT 1200 2300 3000 2200 2900 2700 3600 2300 3100 2100 2700 2700 3600 

800 2000 2700 1900 2500 2400 3100 2000 2600 1800 2400 2300 2900 

100 HST Tophat 0.75 BMT 1200 3600 4600 3200 4200 3600 5400 3400 4400 3000 4000 3400 4800 

800 3200 4000 3000 3700 3800 4600 3000 3800 2800 3600 3600 4000 

100 HST Tophat 0.95 BMT 1200 4000 5000 3700 4700 4300 5400 3800 4800 3600 4500 4000 5800 

800 3500 4400 3200 4100 3600 5000 3400 4200 2900 4000 3400 4800 

120 HST Tophat 0.75 BMT 1200 4300 5400 4000 5000 5100 6000 4200 5200 3900 4800 4900 5800 

800 3400 4800 3000 4400 3400 5300 3200 4500 2800 4200 3200 4900 

120 HST Tophat 0.95 BMT 1200 4800 6000 4400 5600 5100 6300 4600 5600 4200 5400 4800 6200 

800 4200 5200 3800 4900 5000 5800 4000 5000 3700 4600 4400 5600 

150 HST Tophat 0.95 BMT 1200 5600 70000 5000 6600 5600 8000 5200 6800 4800 6400 5200 7800 

800 4600 6200 4100 5800 4600 6800 4200 6000 3900 5500 4200 6600 

150 HST Tophat 1.15 BMT 1200 5100 7700 5700 7200 7000 8000 5800 7400 5200 6900 6200 8000 

800 5000 6800 4800 6300 5000 7800 5000 6500 4600 5500 5000 6800 

PERFORMANCE 

The Typical Spans are designed to 

give information for preliminary 

design and costings and are 

based on the factors noted. Full 

design Load Tables are available 

for specific design and Building 

Consent purposes. 

REGION 1 

- Auckland, Central North Island, South Island (except Marlborough & Southland). 

REGION 2 

- Northland, Wellington, Marlborough, Southland. 

URBAN - Any Built up area with numerous houses/buildings 3 to 5 metres high (Terrain Category 3). 

RURAL - Areas with scattered obstructions, hedges, trees, buildings etc. (Terrain Category 2 1/2). 

SECONDARY USE - Buildings of low importance (secondary nature) where higher roof deflections are acceptable. 

In areas with scattered obstructions, hedges, trees, buildings etc. (Terrain Category 2 1/2). 

SNOW 

- These tables do not apply for elevations in excess of 300 metres or for Canterbury/Otago/Southland 

above 50 metres. In these areas “Snow Loads” should be considered by a qualified engineer. 

FASTENERS - Use 14 gauge tek screws typical. 

Use 2 screws at simple ends and 4 screws at lapped supports typically, except: 

• for fittings to cold rolled purlins with thickness less than 2.5mm BMT, use 

at simple ends use 2 screws, except use 4 screws for 150 Tophats. 

• at lapped supports use 4 screws for 60 Tophats, 6 screws for 100 Tophats, 

8 screws for 120 & 150 Tophats. 

OR Use strap detail. 

LAP 

- Minimum lap between fixing is 15% of Tophat span. 

25

HST tophats 


uniformly distributed Load - single span 

60 x 0.75 60 x 0.9 00 x 0.75 100 x 0.95 120 x 0.75 

Fixings Inward Outward Defl Inward Outward Defl Inward Outward Defl Inward Outward Defl Inward Outward Defl 

G300 2/12 g /12 g /12 g /12 g /14 g 

g0 /12 g / 1.2 mm 2/12 g / 1.2 mm /12 g / 1.5 mm /12 g / 1.5 mm /14 g / 1.5 mm 

Span 

2.0 2.30 1.56 0.88 3.08 2.11 1.16 4.54 3.10 3.90 

2.2 1.90 1.29 0.66 2.55 1.75 0.87 3.76 2.66 2.93 

2.4 1.60 1.08 0.51 2.14 1.47 0.67 3.16 2.24 2.26 4.72 2.58 3.08 3.82 2.67 3.34 

2.6 1.36 0.92 0.40 1.83 1.25 0.53 2.69 1.91 1.78 4.02 2.38 2.42 3.26 2.27 2.62 

2.8 1.18 0.80 0.32 1.57 1.08 0.42 2.32 1.64 1.42 3.47 2.21 1.94 2.81 1.96 2.10 

3.0 1.37 0.94 0.34 2.02 1.43 1.16 3.02 2.00 1.58 2.45 1.71 1.71 

3.2 1.20 0.83 0.28 1.78 1.26 0.95 2.66 1.76 1.30 2.15 1.50 1.41 

3.4 1.07 0.73 0.24 1.57 1.11 0.79 2.35 1.56 1.08 1.90 1.33 1.17 

3.6 0.95 0.65 0.20 1.40 0.99 0.67 2.10 1.39 0.91 1.70 1.19 0.99 

3.8 1.26 0.89 0.57 1.88 1.25 0.78 1.52 1.06 0.84 

4.0 1.14 0.81 0.49 1.70 1.13 0.67 1.38 0.96 0.72 

4.2 1.03 0.73 0.42 1.54 1.02 0.58 1.25 0.87 0.62 

4.4 0.94 0.67 0.37 1.40 0.93 0.50 1.14 0.79 0.54 

4.6 0.86 0.61 0.32 1.28 0.85 0.44 1.04 0.73 0.47 

4.8 0.79 0.56 0.28 1.18 0.78 0.39 0.96 0.67 0.42 

5.0 0.73 0.52 0.25 1.09 0.72 0.34 0.88 0.61 0.37 

5.2 1.01 0.67 0.30 0.81 0.57 0.33 

5.4 0.93 0.62 0.27 0.75 0.53 0.29 

5.6 0.87 0.57 0.24 0.70 0.49 0.26 

5.8 0.65 0.46 0.24 

6.0 

6.2 

6.4 

6.6 

6.8 

7.0 

7.2 

7.4 

7.6 

7.8 

8.0 

8.2 

8.4 

8.6 

8.8 

9.0 

Notes: 

1. Material HST Tophats are rolled from galvanised high strength steel strip 

Grade 500 (with Zinc Weight 275 gm/m 2 ). 

2. Loads The loads are ‘Limit-State’ loads to ‘NZS4203-1992’. 

Defl are serviceability loads, based on defection equal to span/150. 

Outward loads must be adjusted if alternative screw fixings or 

support member thicknesses are used. 

3. Fasteners G300 option - 2.12g indicates 2 off 12 gauge tek screws and assumes 

a support member minimum thickness of 3 millimetres for Grade 

300 steel or a minimum embedment of 37mm into timber with T17 

screws. 

G450 option - 2/14g1.5mm indicates the number and gauge of 

fixings to cold rolled (g450/500) steel and the thickness of the 

support member. 

Outward loads shall be adjusted to a lower value if less screws or 

thinner support members are used. 

4. Bracing Battens screwed transversely along the underside the purlins 

will enhance the performance of the tophat purlins and are 

recommended where supports/restraints are further apart than 30x 

the tophat depth. 

32 

Centroid 

65 

108 

60 

HST 60 TOPHAT 

26

uniformly distributed Load - single span 

120 x 0.9 0 x 0.9 0 x 1. 0 x 1.55 

Fixings Inward Outward Defl Inward Outward Defl Inward Outward Defl Inward Outward Defl 

G300 2/14 g /14 g /14 g /12 g 

g0 /14 g / 1.5 mm 2/14 g / 1.5 mm /14 g / 1.5 mm /14 g / 1.5 mm 

Span 

2.0 

2.2 

2.4 

2.6 4.85 3.43 3.73 

2.8 4.18 2.96 2.99 

3.0 3.64 2.58 2.43 

3.2 3.20 2.26 2.00 

3.4 2.84 2.01 1.67 

3.6 2.53 1.79 1.41 3.18 2.20 2.26 

3.8 2.27 1.61 1.19 2.85 1.97 1.93 3.94 2.42 2.56 

4.0 2.05 1.45 1.02 2.57 1.78 1.65 3.56 2.30 2.19 5.78 3.55 3.01 

4.2 1.86 1.31 0.88 2.33 1.62 1.43 3.23 2.19 1.90 5.24 3.22 2.60 

4.4 1.69 1.20 0.77 2.13 1.47 1.24 2.94 2.09 1.65 4.78 2.93 2.26 

4.6 1.55 1.10 0.67 1.95 1.35 1.09 2.69 1.91 1.44 4.37 2.68 1.98 

4.8 1.42 1.01 0.59 1.79 1.24 0.96 2.47 1.75 1.27 4.02 2.46 1.74 

5.0 1.31 0.93 0.52 1.65 1.14 0.85 2.28 1.62 1.12 3.70 2.27 1.54 

5.2 1.21 0.86 0.47 1.52 1.05 0.75 2.11 1.50 1.00 3.42 2.10 1.37 

5.4 1.12 0.79 0.42 1.41 0.98 0.67 1.95 1.39 0.89 3.17 1.95 1.22 

5.6 1.05 0.74 0.37 1.31 0.91 0.60 1.82 1.29 0.80 2.95 1.81 1.10 

5.8 0.97 0.69 0.34 1.22 0.85 0.54 1.69 1.20 0.72 2.75 1.69 0.99 

6.0 0.91 0.64 0.30 1.14 0.79 0.49 1.58 1.12 0.65 2.57 1.58 0.89 

6.2 0.85 0.60 0.28 1.07 0.74 0.44 1.48 1.05 0.59 2.41 1.48 0.81 

6.4 0.80 0.57 0.25 1.00 0.70 0.40 1.39 0.99 0.54 2.26 1.39 0.74 

6.6 0.94 0.65 0.37 1.31 0.93 0.49 2.12 1.30 0.67 

6.8 0.89 0.62 0.34 1.23 0.87 0.45 2.00 1.23 0.61 

7.0 0.84 0.58 0.31 1.16 0.83 0.41 1.89 1.16 0.56 

7.2 0.79 0.55 0.28 1.10 0.78 0.38 1.78 1.09 0.52 

7.4 0.75 0.52 0.26 1.04 0.74 0.35 1.69 1.04 0.48 

7.6 0.71 0.49 0.24 0.99 0.70 0.32 1.60 0.98 0.44 

7.8 0.94 0.66 0.30 1.52 0.93 0.41 

8.0 0.89 0.63 0.27 1.45 0.89 0.38 

8.2 1.38 0.84 0.35 

8.4 1.31 0.80 0.33 

8.6 1.25 0.77 0.30 

8.8 

9.0 

43 

R3(TYP) 

100 

3 

R3(TYP) 

Centroid 

45 

45° 

10 

2 

5 

91 

163 

HST 100 TOPHAT 

27

HST tophats 


uniformly distributed Load - lapped spans 

60 x 0.75 60 x 0.9 00 x 0.75 100 x 0.95 120 x 0.75 

Fixings Inward Outward Defl Inward Outward Defl Inward Outward Defl Inward Outward Defl Inward Outward Defl 

G300 2/12 g /12 g /12 g /12 g /14 g 

g0 /12 g / 1.2 mm 4/12 g / 1.2 mm /12 g / 1.5 mm 6/12 g / 1.5 mm 6/14 g / 1.5 mm 

Span 

2.0 3.37 2.40 1.89 4.58 2.48 2.46 7.38 3.36 8.27 

2.2 2.69 2.10 1.42 3.65 2.25 1.85 6.10 3.05 8.22 

2.4 2.16 1.76 1.09 2.94 2.07 1.43 5.13 2.80 4.79 7.67 4.20 6.43 5.14 4.60 7.26 

2.6 1.76 1.50 0.86 2.39 1.91 1.12 4.37 2.58 3.77 6.54 3.88 5.06 4.74 4.25 5.71 

2.8 1.44 1.29 0.69 1.96 1.75 0.90 3.77 2.40 3.02 5.64 3.60 4.05 4.41 3.94 4.57 

3.0 1.19 1.13 0.56 1.61 1.53 0.73 3.28 2.24 2.45 4.91 3.36 3.29 3.97 3.68 3.72 

3.2 1.05 0.99 0.46 1.42 1.34 0.60 2.88 2.10 2.02 4.31 3.15 2.71 3.49 3.45 3.06 

3.4 0.93 0.88 0.38 1.26 1.19 0.50 2.56 1.98 1.68 3.82 2.96 2.26 3.09 3.24 2.55 

3.6 0.83 0.78 0.32 1.12 1.06 0.42 2.28 1.87 1.42 3.41 2.80 1.9 2.76 2.89 2.15 

3.8 1.01 0.95 0.36 2.05 1.77 1.21 3.06 2.65 1.62 2.48 2.59 1.83 

4.0 0.91 0.86 0.31 1.85 1.68 1.03 2.76 2.52 1.39 2.24 2.34 1.57 

4.2 1.67 1.60 0.89 2.50 2.40 1.20 2.03 2.12 1.36 

4.4 1.53 1.53 0.78 2.28 2.27 1.04 1.85 1.93 1.18 

4.6 1.40 1.46 0.68 2.09 2.07 0.91 1.69 1.77 1.03 

4.8 1.28 1.36 0.60 1.92 1.90 0.80 1.55 1.63 0.91 

5.0 1.18 1.25 0.53 1.77 1.76 0.71 1.43 1.50 0.80 

5.2 1.09 1.16 0.47 1.63 1.62 0.63 1.32 1.39 0.71 

5.4 1.01 1.07 0.42 1.52 1.50 0.56 1.23 1.28 0.64 

5.6 0.94 1.00 0.38 1.41 1.40 0.51 1.14 1.19 0.57 

5.8 0.88 0.93 0.34 1.31 1.30 0.46 1.06 1.11 0.51 

6.0 0.82 0.87 0.31 1.23 1.22 0.41 0.99 1.04 0.46 

6.2 1.15 1.14 0.37 0.93 0.97 0.42 

6.4 1.08 1.07 0.34 0.87 0.91 0.38 

6.6 1.01 1.01 0.31 0.82 0.86 0.35 

6.8 0.96 0.95 0.28 0.77 0.81 0.32 

7.0 0.73 0.76 0.29 

7.2 0.69 0.72 0.27 

7.4 

7.6 

7.8 

8.0 

8.2 

8.4 

8.6 

8.8 

9.0 

43 

Notes: 

1. Material HST Tophats are rolled from galvanised high strength steel strip Grade 

500 (with Zinc Weight 275 gm/m 2 ). 

2. Loads The loads are ‘Limit-State’ loads to ‘NZS4203-1992’. 

Defl are serviceability loads, based on defection equal to span/150. 

Outward loads must be adjusted if alternative screw fixings or support 

member thicknesses are used. 

3. Fasteners G300 option - 2.12g indicates 2 off 12 gauge tek screws and assumes 

a support member minimum thickness of 3 millimetres for Grade 300 

steel or a minimum embedment of 37mm into timber with T17 screws. 

G450 option - 2/14g1.5mm indicates the number and gauge of 

fixings to cold rolled (g450/500) steel and the thickness of the support 

member. 

Outward loads shall be adjusted to a lower value if less screws or 

thinner support members are used. 

4. Lapping Laps shall be a minimum of 15% of the span between supports, 

measured between the lap screws. 

Provide 2 screws at lap ends for 60/100 tophats and 4 screws for 

120/150 tophats. 

4. Bracing Battens screwed transversely along the underside the purlins will 

enhance the performance of the tophat purlins and are recommended 

where supports/restraints are further apart than 30x the tophat depth. 

10 

R3(TYP) 

Centroid 

R3(TYP) 

65 

3 

98 

170 


2 

5 

120 

28

uniformly distributed Load - lapped spans 

120 x 0.9 0 x 0.9 0 x 1. 0 x 1.55 

Fixings Inward Outward Defl Inward Outward Defl Inward Outward Defl Inward Outward Outward Defl 

G300 414 g /14 g 6/14 g 6/12 g 

g0 6/14 g / 1.5 mm 6/14 g / 1.5 mm 8/14 g / 1.5 mm 8/14 g / 1.5 mm 

Span 

2.0 

2.2 

2.4 

2.6 

2.8 

3.0 5.92 3.68 5.08 

3.2 5.20 3.45 4.19 

3.4 4.61 3.25 3.49 

3.6 4.11 3.07 2.94 5.16 3.07 4.90 

3.8 3.69 2.91 2.50 4.63 2.91 4.17 6.41 3.87 5.35 

4.0 3.33 2.76 2.15 4.18 2.76 3.58 5.78 3.68 4.58 9.40 4.80 3.68 6.24 

4.2 3.02 2.63 1.85 3.79 2.63 3.09 5.25 3.50 3.96 8.52 4.57 3.50 5.39 

4.4 2.75 2.51 1.61 3.46 2.51 2.69 4.78 3.35 3.44 7.77 4.36 3.35 4.69 

4.6 2.52 2.40 1.41 3.16 2.40 2.35 4.37 3.20 3.01 7.10 4.17 3.20 4.11 

4.8 2.31 2.300 1.24 2.90 2.30 2.07 4.02 3.07 2.65 6.52 4.00 3.07 3.61 

5.0 2.13 2.21 1.10 2.68 2.21 1.83 3.70 2.94 2.35 6.01 3.84 2.94 3.20 

5.2 1.97 2.08 0.98 2.47 2.12 1.63 3.42 2.83 2.09 5.56 3.69 2.83 2.84 

5.4 1.83 1.93 0.87 2.29 2.04 1.45 3.17 2.73 1.86 5.16 3.56 2.73 2.54 

5.6 1.70 1.80 0.78 2.13 1.97 1.30 2.95 2.63 1.67 4.67 3.43 2.63 2.28 

5.8 1.58 1.67 0.70 1.99 1.90 1.17 2.75 2.54 1.50 4.35 3.31 2.54 2.05 

6.0 1.48 1.56 0.64 1.86 1.84 1.06 2.57 2.45 1.36 4.06 3.20 2.45 1.85 

6.2 1.39 1.47 0.58 1.74 1.78 0.96 2.41 2.37 1.23 3.81 3.10 2.37 1.68 

6.4 1.30 1.38 0.52 1.63 1.70 0.87 2.26 2.30 1.12 3.57 3.00 2.30 1.52 

6.6 1.22 1.29 0.48 1.54 1.59 0.80 2.12 2.23 1.02 3.36 2.91 2.23 1.39 

6.8 1.15 1.22 0.44 1.45 1.50 0.73 2.00 2.12 0.93 3.16 2.82 2.16 1.27 

7.0 1.09 1.15 0.40 1.37 1.42 0.67 1.89 2.00 0.86 2.99 2.74 2.10 1.17 

7.2 1.03 1.09 0.37 1.29 1.34 0.61 1.79 1.89 0.79 2.82 2.67 2.04 1.07 

7.4 0.97 1.03 0.34 1.22 1.27 0.56 1.69 1.79 0.72 2.67 2.53 1.99 0.99 

7.6 0.92 0.98 0.31 1.16 1.20 0.52 1.60 1.69 0.67 2.53 2.40 1.94 0.91 

7.8 0.88 0.93 0.29 1.10 1.14 0.48 1.52 1.61 0.62 2.41 2.27 1.89 0.84 

8.0 0.83 0.88 0.27 1.05 1.09 0.45 1.45 1.53 0.57 2.29 2.16 1.84 0.78 

8.2 0.99 1.03 0.42 1.38 1.46 0.53 2.18 2.06 1.80 0.72 

8.4 0.95 0.98 0.39 1.31 1.39 0.49 2.07 1.96 1.75 0.67 

8.6 0.90 0.94 0.36 1.25 1.32 0.46 1.98 1.87 1.71 0.63 

8.8 1.20 1.25 0.43 1.89 1.79 1.67 0.59 

9.0 1.14 1.21 0.40 1.81 1.71 1.64 0.55 

43 

R3(TYP) 

100 

150 

3 

Centroid 

R3(TYP) 

10 

2 

5 


110 

183 

29

oof selector 

worked Example - single span purlins 

Terrain Categories 

Exposed Open 

Rural 

Sheltered Rural 

Urban 

2 

City 

Maximum Purlin Span Maximum Cladding Span 

Internal 

4000 

3500 

3000 

2500 

2000 

1500 

1000 

900 

15000 

14000 

13000 

12000 

11000 

10000 

9000 

8000 

7000 

6000 

5000 

4000 

3000 

2000 

1000 

7 

6 

400/20 (3 bri) 

400/20 

400/20 

350/18 

300/18 

300/15 

250/18 

250/15 

200/18 

200/15 

200/12 

150/15 

150/12 

100/19 

100/15 

100/10 

LOW WIND 

HST purlins 

MEDIUM WIND 

top hat 

Purlins 

150 x 1.95 

150 x 1.15 

150 x 0.95 

120 x 0.95 

100 x 0.95 

100 x 0.75 

60 x 0.95 

60 x 0.75 

HIGH WIND 

VERY HIGH WIND 

1 

Example for Single Span Purlins 

Wind Regions 

Central North Island 

9 

9 

Auckland / South Island 

Southern North Island 

Wellington / Far South 

Northland 

7 

7 

Northland 

Kaitaia 

9 Multispan 0.55 

Whangarei 

3 

(High Rib) 

8 

7 ST900 0.55 

Morrinsville 

(Medium Rib) 

Auckland 

Tauranga 

4 6 

Auckland 

Rotorua 

Huntly 

6 ST900 0.40 (Medium Rib) 

Hamilton 

Central NI 

Gisborne 

4 Plumbdek / Trimline / Trimform 0.55 (Low Rib) New Plymouth 

Taupo 

8 Multispan 0.40 (High Rib) 

Ohakune 

Napier 

Waiouru Waipawa 

2 3 5 

3 4 

Wanganui 

2 

Waipukurau 

3 Plumbdek / Trimline / Trimform 0.40 (Low Rib) 

Nelson 

Southern NI 

Blenheim 

Palmerston North 

1 

1 

2 Custom ORB 0.55 

Westport 

Upper Hutt 

South Island 

Wellington 

1 

Wellington 

Custom ORB 0.40 

Hokitika 

Kaikoura 

Haast 

Hanmer Springs 

Culverden 

Twizel 

Milford Sound 

Cromwell 

Alexandra 

Christchurch 

Methven 

Timaru 

Dunedin 

Far South 

Invercargill 

Specific Design 

Required 

Consult 

Engineer 

The following roof selector graphs are intended to provide preliminary sizing information 

and are not intended to be used for final building design or ‘Building Consent’ purposes. 

The following example determines a proposed roofing option for a building near Hamilton 

on open farmland with little shelter from trees or other buildings. The building is 7.5 metres 

high to the apex and it is intended to use portal frames with 9 metre bays. The example 

assume slow profile cladding (eg. Trimline). Options for different cladding types or purlin 

spacings may be determined in the same manner. 

Method: 

Wind Zone Selector 

1. Select Region eg. Central North Island 

2. Select the type of Terrain 

• Exposed Open – terrain with few or no obstructions. 

• Rural – open terrain with few scattered obstructions such as grassland, airfields, 

riverflats, lakes or sea. 

• Sheltered Rural – areas with some sheltering from trees and adjacent buildings. 

• Urban – industrial and residential suburbs with numerous closely spaced 

obstructions the size of domestic houses. 

• City – terrain with numerous large, high (10m to 30m high) and closely spaced 

obstructions such as large city centres and well developed industrial complexes. 

3. Trace a line from this intersection point equidistant between the Wind Zone lines down 

to the Cladding Selector 

Cladding Selector 

4. Select Cladding Type eg. 0.4BMT Trimline 

5. The maximum purlin spacing for this sheeting is 1600mm. 

Note purlin spacings at sheet ends should be reduced by 20% eg. 1280mm. 

6. Trace a line down from this intersection to the Purlin Selector. 

Purlin Selector 

7. Select Support Rafter Spacings eg. 9 metres. 

8. The intersection of lines indicates that the purlins should be 300/18HST purlins with 

one row of bridging. 

Solution: 

Use 0.4BMT Trimline on 300/18HST purlins at 1.6m centres. 

With 1 row of bridging; And 1.28m max. spacings at sheet ends. 

Refer to the Roof Selector sheets for general notes. 

30

oof selector 

single span purlins 


Exposed Open 

Rural 


Urban 

City 


Internal 

4000 

3500 

3000 

2500 

2000 

1500 

1000 

900 

15000 

14000 

13000 

12000 

11000 

10000 

9000 

8000 

7000 

6000 

5000 

4000 

3000 

2000 

1000 

400/20 (3 bri) 

400/20 

400/20 

350/18 

300/18 

300/15 

250/18 

250/15 

200/18 

200/15 

200/12 

150/15 

150/12 

100/19 

100/15 

100/10 

LOW WIND 

HST purlins 

MEDIUM WIND 

top hat 

Purlins 

150 x 1.95 

150 x 1.15 

150 x 0.95 

120 x 0.95 

100 x 0.95 

100 x 0.75 

60 x 0.95 

60 x 0.75 

HIGH WIND 


Wind Regions 


9 

9 




Northland 

7 

7 

Northland 

Kaitaia 


Whangarei 

(High Rib) 

8 

7 ST900 0.55 

Morrinsville 

(Medium Rib) 

Auckland 

Tauranga 

4 6 

Auckland 

Rotorua 

Huntly 


Hamilton 

Central NI 

Gisborne 


Taupo 


Ohakune 

Napier 


2 3 3 

Wanganui 

2 

Waipukurau 


Nelson 

Southern NI 

Blenheim 


1 

1 


Westport 

Upper Hutt 

South Island 

Wellington 

1 

Wellington 


Hokitika 

Kaikoura 

Haast 


Culverden 

Twizel 

Milford Sound 

Cromwell 

Alexandra 

Christchurch 

Methven 

Timaru 

Dunedin 

Far South 

Invercargill 

Notes 

1. This purlin selector chart is designed to be a quick reference guide only. Full design 

load tables are available for design and Building Consent purposes. 

2. HST purlins require 1 row of bracing typical except provide 2 rows where shaded. 

Laps shall be a minimum of 10% of purlin span. 

3. Reduce purlin spacings by 20% at sheet ends. 

4. Refer to Steel & Tube product data sheets for installation information and max 

cladding end spans. For high wind and greater 0.4 BMT cladding shall be fixed at 

every rib throughout. 

5. Roof traffic shall be along purlin lines and in sheeting pans. Purlin spans should be 

reduced where heavy roof traffic is expected, refer to Steel & Tube or use 0.55 BMT 

material at 0.4 BMT nominated spans. 

6. Snow loads - consult a qualified design engineer for buildings situated above the 

following elevations: 

- Central and Lower North Island above 600 metres. 

- West Coast and Marlborough above 450 metres. 

- Canterbury above 200 metres. 

- Otago and Southland above 300 metres. 

7. Habitable buildings, ceilings or sprinkers - consult a qualified design engineer for 

the consideration of the additional loads. 

8. This design chart is based on NZS4203:1992 wind loads with: 

- Maximum apex height = 7.5 metres 

- Eaves height / Building width < 0.6 

- Even distribution of openings Cpi = + 0.3 (no dominant openings) 

- A local pressure allowance has been included over half purlin length 

9. Tophat spans may be limited by fixings. This chart assumes the following fixings 

at each internal support: 

TopHat timber & Hot Cold Formed 

Rolled Steel Steel (t>1.5) 

60 2 x 12 g 2 x 12 g 

100 2 x 14 g 2 x 14 g 

120 / 150 2 x 14 g 4 x 14 g 


Required 

Consult 

Engineer 

For all other cases and if the requried fixings can not be achieved consult a qualified 

design engineer for alternative strap hold down. 

31

oof selector 

Continuous span purlins 


Exposed Open 

Rural 


Urban 

City 


Internal 

4000 

3500 

3000 

2500 

2000 

1500 

1000 

900 

16000 

15000 

14000 

13000 

12000 

11000 

10000 

9000 

8000 

7000 

6000 

5000 

4000 

3000 

400/20 

400/20 

350/18 

300/18 

300/15 

250/18 

250/15 

200/18 

200/15 

200/12 

150/15 

150/12 

400/20 (3 bri) 

LOW WIND 

HST purlins 

MEDIUM WIND 

top hat 

Purlins 

150 x 1.55 

150 x 1.15 

150 x 0.95 

120 x 0.95 

100 x 0.95 

100 x 0.75 

HIGH WIND 


Wind Regions 


9 

9 




Northland 

7 

7 

Northland 

Kaitaia 


Whangarei 

(High Rib) 

8 

7 ST900 0.55 

Morrinsville 

(Medium Rib) 

Auckland 

Tauranga 

4 6 

Auckland 

Rotorua 

Huntly 


Hamilton 

Central NI 

Gisborne 


Taupo 


Ohakune 

Napier 


2 3 3 

Wanganui 

2 

Waipukurau 


Nelson 

Southern NI 

Blenheim 


1 

1 


Westport 

Upper Hutt 

South Island 

Wellington 

1 

Wellington 


Hokitika 

Kaikoura 

Haast 


Culverden 

Twizel 

Milford Sound 

Cromwell 

Alexandra 

Christchurch 

Methven 

Timaru 

Dunedin 

Far South 

Invercargill 

Notes 

1. This purlin selector chart is designed to be a quick reference guide only. Full design 

load tables are available for design and Building Consent purposes. 

2. HST purlins require 1 row of bracing typical except provide 2 rows where shaded. 

Laps shall be a minimum of 10% of purlin span. 

3. Reduce purlin spacings by 20% at sheet ends. 

4. Refer to Steel & Tube product data sheets for installation information and max 

cladding end spans. For high wind and greater 0.4 BMT cladding shall be fixed at 

every rib throughout. 

5. Roof traffic shall be along purlin lines and in sheeting pans. Purlin spans should be 

reduced where heavy roof traffic is expected, refer to Steel & Tube or use 0.55 BMT 

material at 0.4 BMT nominated spans. 

6. Snow loads - consult a qualified design engineer for buildings situated above the 

following elevations: 

- Central and Lower North Island above 600 metres. 

- West Coast and Marlborough above 450 metres. 

- Canterbury above 200 metres. 

- Otago and Southland above 300 metres. 

7. Habitable buildings, ceilings or sprinkers - consult a qualified design engineer for 

the consideration of the additional loads. 

8. This design chart is based on NZS4203:1992 wind loads with: 

- Maximum apex height = 7.5 metres 

- Eaves height / Building width < 0.6 

- Even distribution of openings Cpi = + 0.3 (no dominant openings) 

- A local pressure allowance has been included over half purlin length 

9. Tophat spans may be limited by fixings. This chart assumes the following fixings 

at each internal support: 

TopHat timber & Hot Cold Formed 

Rolled Steel Steel (t>1.5) 

60 4 / 12 g 6 / 12 g 

100 / 120 / 150 6 / 14 g 8 / 12 g 


Required 

Consult 

Engineer 

2000 

60 x 0.95 

60 x 0.75 

For all other cases and if the required fixings can not be achieved consult a qualified 

design engineer for alternative strap hold down. 

32

floor joist spans 

HST tophats & hst purlins - floor joist spans 

Single Span 

Double Span 

Spacing 

spacing 

400 450 600 400 450 600 

HST Tophats 

60 x 0.75 1.05 1.00 0.95 1.25 1.20 1.10 

60 x 0.95 1.15 1.10 1.05 1.35 1.30 1.20 

100 x 0.75 1.80 1.70 1.60 2.10 2.00 1.90 

100 x 0.95 2.00 1.90 1.80 2.40 2.20 2.00 

120 x 0.75 2.20 2.10 1.90 2.50 2.40 2.10 

120 x 0.95 2.40 2.30 2.10 2.90 2.70 2.40 

150 x 0.95 2.90 2.80 2.50 3.50 3.30 2.80 

150 x 1.15 3.20 3.00 2.70 3.90 3.60 3.20 

150 x 1.55 3.60 3.40 3.00 4.30 4.10 3.60 

HST Purlins 

100/19 2.30 2.20 2.10 2.80 2.60 2.40 

150/12 3.10 2.90 2.70 3.80 3.50 3.10 

150/15 3.40 3.20 2.90 4.10 3.80 3.40 

150/18 3.60 3.40 3.10 4.30 4.00 3.50 

200/12 4.10 3.90 3.60 5.00 4.70 4.10 

200/15 4.70 4.30 3.90 5.40 5.20 4.50 

200/18 5.10 4.70 4.20 5.80 5.60 4.80 

250/13 5.50 5.10 4.50 6.00 5.60 4.90 

250/15 5.80 5.40 4.80 6.50 6.20 5.40 

250/18 6.20 5.80 5.10 6.90 6.80 6.00 

300/15 7.00 6.70 5.80 7.60 7.20 6.30 

300/18 7.40 7.30 6.30 8.20 8.00 7.10 

350/18 8.40 8.20 7.10 9.20 8.90 7.70 

400/20 9.70 9.50 8.40 10.50 10.10 8.80 

Notes: 

1. Loads Spans are in metres and are based on controlling floor vibrations. 

The above spans are suitable for applied live loads of 5 kPa. 

2. Durability HST purlins and tophats have a zinc weight of 275 gm/m2 and are suitable for use 

in an internal environment. 

Durability requirements should be checked for use elsewhere including subfloors. 

3. Bracing For increased performance where ceilings are not installed, we recommend providing a transverse brace 

(eg. ceiling batten - CB20 or similar, to the underside of the floor joists at 3 metre centres typical. 

For futher information, please call us on 0800 478 335. 

DISCLAIMER 

This publication is intended to provide accurate information to the best of our knowledge in regard to HST Purlins and Girts. It does not constitute a complete description of the goods or an express statement 

about their suitability for any particular purpose. It is only intended as a general guide and not as a substitute for professional technical advice.

To find out more about our extensive range 

of products and services: 

Steel 

Rural Products 

Pipe, Fittings & Valves Industrial Products 

Stainless Steel 

Reinforcing 

Fastenings 

Roofing, Cladding, 

Chain & Rigging 

Rainwater Systems 

& Purlins 

CONTACT US TODAY: 

0800 478 335 

www.steelandtube.co.nz 

S&T029

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