What Thickness Corrugated Roofing Sheet Do I Need?
It’s one of the first questions people ask before ordering corrugated roofing sheets, and it’s a sensible one. Choose a sheet that isn’t suitable for the job, and it may not perform as expected. On the other hand, there’s little point in paying for heavier sheeting if your project doesn’t require it.
The right thickness depends on more than the building’s size or type. You also need to consider the sheet profile, spacing between supports, and the roof’s location and intended use.
Here’s what you need to know before choosing.
What corrugated roofing sheet thicknesses are available?
Corrugated steel roofing sheets are available in several thicknesses, depending on the manufacturer and profile. You’ll commonly come across sheets around 0.5mm to 0.7mm thick, although other specifications are also available.
As a general rule, thicker steel sheets are stiffer and more resistant to bending. However, that doesn’t mean you can choose a roofing sheet based on thickness alone.
The shape and depth of the corrugated profile, spacing between supports, expected loads, and the building’s location can all affect how a sheet performs.
For example, a thinner sheet with adequate support may be perfectly suitable for one project. At the same time, another roof may require a different specification because of wider support spacing or greater exposure.
Is 0.7mm roofing sheet better than 0.5mm?
Not necessarily. A 0.7mm steel sheet contains more material and will generally be stiffer than a comparable 0.5mm sheet with the same profile, but that doesn’t automatically make it the better choice for every roof.
A lighter sheet may be perfectly adequate when it is properly supported and suitable for the intended application. Likewise, simply choosing thicker steel doesn’t compensate for inadequate supports or an unsuitable roof design.
It’s better to choose the sheet specification based on the project’s requirements rather than assuming the thickest option is always best.
What determines the roofing sheet thickness you need?
Consider several factors before choosing corrugated metal sheeting for a roof.
- How far apart are the roof supports?
Corrugated roofing sheets are normally supported by timber or steel purlins running beneath them.
Support spacing matters because the sheet must span the distance between supports. As the unsupported distance increases, the demands placed on the sheet also increase.
You shouldn’t determine suitable support spacing from sheet thickness alone. You also need to consider the profile, material, and expected loads, so check the specifications for the roofing sheet you’re considering.
- What are you roofing?
Corrugated metal sheets are used on everything from small garden structures to workshops, garages and agricultural buildings.
The size and design of the structure can significantly affect the demands placed on the roofing material.
A small covered outdoor area with closely spaced supports, for example, presents different requirements from a large open-sided outbuilding in an exposed location.
Rather than choosing a sheet purely because it’s being used on a shed, garage or workshop, consider how that particular structure has been built.
- How exposed is the location?
A roof in a sheltered garden is very different from one in an exposed coastal or rural location.
Wind loading can be particularly important on exposed buildings, and both the roofing material and how it’s secured need to suit the conditions.
This is another reason why thickness shouldn’t be considered in isolation. The roof structure, sheet profile and fixings all contribute to the performance of the finished roof.
- Is it a permanent or temporary structure?
Think about what you’re building and how long you expect it to remain in place.
A permanent workshop, garage or outbuilding will naturally have different requirements from a temporary shelter or small garden project.
Whatever you’re building, the supporting structure and roofing sheets should suit their intended use, not just the building type.
What does 24 SWG mean on roofing sheets?
You may see corrugated steel thickness described using SWG, which stands for Standard Wire Gauge.
This is another way to express steel thickness. One important thing to remember is that gauge numbers don’t work in the same way as millimetres: a lower SWG number represents thicker steel.
Our corrugated roofing sheets are manufactured from 0.54mm galvanised steel, equivalent to 24 SWG.
When comparing roofing sheets from different suppliers, looking at the stated thickness in millimetres is often the simplest way to understand what you’re comparing.
Our 24 SWG corrugated steel sheets
If this specification suits your project, you can view our 0.54mm (24 SWG) galvanised steel corrugated roofing sheets, available in 8ft and 10ft lengths for roofing and cladding applications.
What can 0.54mm corrugated roofing sheets be used for?
Our 0.54mm galvanised corrugated sheets can be used for a variety of roofing and cladding projects where the sheet specification and supporting structure are appropriate.
Typical applications can include:
- Garden sheds and storage buildings
- Workshops and garages
- Covered outdoor areas
- Lean-to roofs
- General outbuildings
- Agricultural applications
- Wall and side cladding
These are examples, not a guarantee that 0.54mm sheeting will suit every structure of that type.
Two garages, for instance, could have completely different dimensions, support spacing and exposure to wind. You need to consider each roof individually rather than choosing a sheet based on the building’s name.
Uses beyond roofing
Roof coverings aren’t the only application for this type of sheeting. The strength, weather resistance and practical corrugated profile also make metal sheets useful for other building and outdoor projects. If you’re considering a different application, look at other uses for corrugated metal roofing sheets, including cladding, screening and different construction projects.
Does the length of the roofing sheet affect the thickness you need?
Length and thickness are separate measurements, but you need to consider both when planning a roof.
We supply corrugated roofing sheets in 8ft and 10ft lengths, so the best option largely depends on your roof’s dimensions and slope.
Using a sheet that closely matches the required roof length can help reduce unnecessary cutting and may also reduce the number of joins required.
However, a longer sheet doesn’t remove the need for adequate support underneath it. The supporting structure still needs to suit the sheet profile, span, and expected loads.
Can you walk on corrugated metal roofing sheets?
Corrugated roofing sheets shouldn’t be treated as a normal walkable surface.
Although thicker steel is generally stiffer, choosing a heavier sheet doesn’t automatically make a roof safe to walk on. Roofing sheets can bend or become damaged, and there is also a risk of falling through or from the roof.
If you need access for installation, inspection, or maintenance, use appropriate access equipment and follow safe work procedures.
Don’t overlook the supporting structure
It’s easy to concentrate on the thickness of the roofing sheet, but what’s underneath it is just as important.
Purlins need to provide adequate support, and sheets should be installed using suitable roofing fixings and weatherproof washers. Sheet overlaps, fixing positions, and support spacing should suit the specific profile and application.
Correct installation keeps the sheets secure, limits unnecessary movement, and helps prevent water from getting through the roof.
So, what thickness corrugated roofing sheet should I choose?
There’s no single thickness that’s right for every corrugated roof.
Thicker steel will generally provide greater stiffness than a thinner sheet of the same profile, but thickness is only one part of choosing suitable roofing. You also need to consider the profile, support spacing, roof dimensions, expected loads, location and how the sheets will be fixed.
For projects with specific structural or loading requirements, check the appropriate span and load information rather than selecting a sheet on thickness alone.
We supply corrugated roofing sheets in two lengths:
If you’re unsure whether our 0.54mm sheets are suitable for your project, tell us what you’re building, the approximate roof dimensions, and how it will be supported, and we’ll help you determine whether they’re appropriate before you order.