Tophat Purlins

Rollforming Services' Tophat Purlins are a versatile, lightweight, economical and an easy-to-use product for roof purlins, wall girts, floor joists, and many other applications such as carports, fencing and racking.

Tophat Purlins are a versatile and an easy to use product, typically used as roof purlins and wall girts, in applications such as carports, fencing, racking, farm buildings, and light commercial sheds.

Ideal for spans from 3 to 7 metres, Tophat Purlins provide a lightweight and economical alternative to standard timber beams or steel C-purlins.

  • Tophat Purlins are fastened directly to their supports with Tek screws, which results in a saving on cleats.
  • Tophat Purlins do not twist because of their symmetrical section, so no braces or nogs are needed.
  • The Tophat profile is easily lapped for optimal performance.
Typical Tophat Purlin on steel C beam
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Typical Tophat Purlin on double steel C beam
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Typical Tophat in high wind zone connection detail
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Typical Tophat Purlin overlap connection detail
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Tophat Purlins Height (mm) Material Thickness (mm) Lengths Available Kg per m
DS60 x 0.75mm 60 0.75 Run to Order 1.225
DS60 x 0.95mm 60 0.95 Run to Order 1.531
DS100 x 0.75mm 100 0.75 Run to Order  1.947
DS100 x 0.95mm 100 0.95 Run to Order  2.434
DS120 x 0.75mm 120  0.75  Run to Order 2.918 
DS120 x 0.95mm 120 0.95 Run to Order 2.748
DS150 x 0.95mm 150 0.95 Run to Order 3.219
DS150 x 1.15mm 150 1.15 Run to Order 3.862
Tophat Purlins are rolled from G550 steel hot-dipped galvanised with coating weight of Z275

Tophat Purlins are manufactured from G550 steel hot-dipped galvanised with a coating weight of Z275. This gives good protection in most exposed internal environments, and for external use in moderate coastal environments. Z450 galvanised steel coating is also available upon request.

To ensure durability of product, please note the following:

  • Where used in a lined interior dwelling, a thermal break should be installed between the Tophat and the cladding to avoid thermal bridging.
  • Where sections are exposed to salt spray but not rain, 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.

Please refer to the NZ Steel Durability Statement

Use 14 gauge Tek screws.

  • Typically
    • use 2 screws at simple ends
    • use 4 screws at lapped supports

With the exception of the following:

  • For fittings to cold rolled purlins with thickness less than 2.5mm BMT
    • use 2 screws at simple ends
    • use 4 screws for the 150mm Tophats at simple ends
  • For lapped supports use
    • 4 screws for the 60mm Tophats
    • 6 screws for the 100mm Tophats
    • 8 screws for the 120mm & 150mm Tophats
    • OR use strap detail as required

Tophat Purlins 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.

Cutting is preferably done by shear or hacksaw. When using abrasive disc blades, care must be taken to ensure the flammable swarf produced does not affect other materials, and the burred edge should be cleaned off at the completion of cutting. Finish the cut end with a galv spray to add protection.

Jamb Flashings

  • Jamb Flashings are used where a door or window is cut into the side of a building to flash off the cladding and Tophat girt.
  • They are available in two variations, and are made from G250 Z275 galvanised steel
Jamb Flashings Description Internal Diameter (mm) Height (mm) Material Thickness (mm) Lengths Available (mm) Kg per m
J1 62ID x 52 x 1.55mm Jamb Flashing Channel 62 52 1.55 1.0, 2.7, 4.0, 6.0 2.049
J2 102ID x 52 x 1.55mm Jamb Flashing Channel 102 52 1.55 1.0, 2.7, 4.0, 6.0 2.551
J3 122ID x 52 x 1.55mm Jamb Flashing Channel 122 52 1.55 1.0, 2.7, 4.0, 6.0 2.802
J4 152ID x 52 x 1.55mm Jamb Flashing Channel 152 52 1.55 1.0, 2.7, 4.0, 6.0 3.179
J1 60ID x 60 x 40 x 1.2mm Odd Leg Jamb Flashing Channel 60 60 1.2 3.2 1.541
J2 100ID x 60 x 40 x 1.2mm Odd Leg Jamb Flashing Channel 100 60 1.2 3.2 1.934
J3 120ID x 60 x 40 x 1.2mm Odd Leg Jamb Flashing Channel 120 60 1.2 3.2 2.13
J4 150ID x 60 x 40 x 1.2mm Odd Leg Jamb Flashing Channel 150 60 1.2 3.2 2.425
Jamb Flashings are made from G250 steel hot-dipped galvanised with coating weight of Z275


THF Flashing Plates

THF Flashing Plates are used where Tophat Purlins pass through internal or external wall linings and fire-rated wall linings. They provide a neat and tidy hole for fixing of the sheets, which would otherwise be hard to achieve. Lapped Tophat Purlins can also pass through the THF Flashing Plates. Made with AZ150 Steel, they can be spray painted to match cladding if required.

Product Sizes Available (mm) Height (mm) Width (mm) Material Thickness (mm) Bundles kg per m
THF60 Flashing Plate 120 x 233 x 23 x 0.55 120 233 0.55 Opening to suit a single or lapped DS60 Tophat 20 0.136
THF100 Flashing Plate 160 x 286 x 23 x 0.55 160 286 0.55 Opening to suit a single or lapped DS100 Tophat 20 0.213
THF120 Flashing Plate 180 x 293 x 23 x 0.55 180 293 0.55 Opening to suit a single or lapped DS120 Tophat 20 0.245
THF150 Flashing Plate 210 x 306 x 23 x 0.55 210 306 0.55 Opening to suit a single or lapped DS150 Tophat 20 0.297
THF Flashing Plates are made from AZ150 steel

Tophat Sectional Properties
Tophat Section Thickness Area Mass per Unit Length Second Moment
Area (Full)
Centre of Gravity Section Modulus (Full) Radius of Gyration Shear Centre Torsion Constant Warping Constant Mono Symmetry Constant
t(BMT)
mm
mm2 kg/m lx
106mm4
ly
106mm4
yc
mm
zx
103mm3
zy
103mm3
rx
mm
ry
mm
ye
mm
J
mm4
lw
109mm6
βx
mm
60 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 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 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 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 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 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 Tophat 0.75 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 Tophat 0.95 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


BMT = base metal thickness

Tophat Section Purlin Spacing
(mm)
Region 1 Region 2
Urban Rural Secondary Use Urban Rural Secondary Use
Simple Lapped Simple Lapped Simple Lapped Simple  Lapped Simple Lapped Simple Lapped
60 Tophat 0.75 BMT 1200
1800
2200
1800
2800
2400
2000
1700
2600
2100
2600
2100
3200
2700
2100
1800
2700
2300
1900
1700
2500
2200
2500
1900
3200
2500
60 Tophat 0.95 BMT 1200
1800
2300
2000
3000
2700
2200
1900
2900
2500
2700
2400
3600
3100
2300
2000
3100
2600
2100
1800
2700
2400
2700
2300
3600
2900
100 Tophat 0.75 BMT 1200
1800
3600
3200
4600
4000
3200
3000
4200
3700
3600
3800
5400
4600
3400
3000
4400
3800
3000
2800
4000
3600
3400
3600
4800
4000
100 Tophat 0.95 BMT 1200
1800
4000
3500
5000
4400
3700
3200
4700
4100
4300
3600
5400
5000
3800
3400
4800
4200
3600
2900
4500
4000
4000
3400
5800
4800
120 Tophat 0.75 BMT 1200
1800
4300
3400
5400
4800
4000
3000
5000
4400
5100
3400
6000
5300
4200
3200
5200
4500
3900
2800
4800
4200
4900
3200
5800
4900
120 Tophat 0.95 BMT 1200
1800
4800
4200
6000
5200
4400
3800
5600
4900
5100
5000
6300
5800
4600
4000
5600
5000
4200
3700
5400
4600
4800
4400
6200
5600
150 Tophat 0.95 BMT 1200
1800
5600
4600
7000
6200
5000
4100
6600
5800
5600
4600
8000
6800
5200
4200
6800
6000
4800
3900
6400
5500
5200
4200
7800
6600
150 Tophat 1.15 BMT 1200
1800
5100
5000
7700
6800
5700
4800
7200
6300
7000
5000
8000
7800
5800
5000
7400
6500
5200
4600
6900
5500
6200
5000
8000
6800

  • 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.

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