| What you need to know about Roof Sheeting in cyclonic areas ... |
| Material Thickness |
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For all roof sheeting, whether your area is cyclonic or not, manufacturers recommend
a material thickness of 0.42mm BMT (i.e. 0.47mm TCT)
or greater.
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| Roof sheeting fasteners |
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The use of roofing screws with cyclonic assemblies gives your shed's roof sheeting
the best chance of surviving the cyclonic winds. Of course the rest of the frame needs the strength
and rigidity to bear the force of these winds, but your shed frame is of little use without its
roof sheeting.
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| When comparing quotes be sure you check
that other companies quote on roofing material and roofing screws that follows
manufacturers' recommendations for material thickness, fastener type and purlin spacing.
Also, make sure you read our information below on purlin spacing.
View Bluescope's Cyclonic Design Manual.
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| Your Choices |
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We offer Trimdek and Custom Orb (corrugated) profiles. Both
profiles cost the same per square metre of actual sheeting. Custom Orb may end
up being more expensive if extra purlins are required. See Custom Orb below.
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| Trimdek® |
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Trimdek is a stronger profile. Hence it allows for a
slightly wider purlin spacing in the roof frame. In some cases it may mean
fewer purlins are required.
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Trimdek is a deeper profile. Hence it
can handle runoff from a higher rainfall intensity at a given roof slope.
View Trimdek brochure.
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| Custom Orb® |
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Custom Orb (corrugated) is often chosen if people want to
have the more traditional Aussie appearance. It has slightly narrower maximum
purlin spacings than Trimdek. In some cases more purlins may be required.
View Custom Orb brochure.
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| Purlin Spacing |
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Manufacturers specify minimum roof support spacings (i.e. purlin spacings)
for their roof sheeting materials. The table shows
the maximum recommended purlin spacings in cyclonic areas (i.e. Wind Region C). Note that these
maximums may decrease for Terrain Category 1.
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In the next step of your quote, Framing Options, you can view the purlin positions
in each of the frame options available to you. These are calculated to always meet the requirements
for the roof sheeting you select.
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Also, the detailed quote you receive by email from us, will show the number
of purlins and their respective spacings. This will enable you to do a thorough comparison with
other quotes. When comparing quotes be sure you check
that other quotes meet manufacturers' recommendations for purlin (support) spacing
with roofing material.
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| Roof Profile | Trimdek
0.42mmBMT | Custom Orb
0.42mmBMT |
| End spans | 1000mm | 900mm |
| Internal spans | 1475mm | 1200mm |
Taken from the Lysaght Cyclonic Area Design Manual - Steel Roofing and Walling
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