Choosing the right roof sheeting in Australia can get a little confusing. There are numerous considerations to take into account when considering which metal roofing profile to use for your roof. While price may be one of the consideration, there are much more weightier considerations such as the pitch of the roof, the amount of support required and the final look of the finish.
It all starts with the pitch - the most important consideration when deciding on the profile. This is because not all profiles will support a low pitch or specifically a pitch below 5 degrees. So what exactly is the pitch?
The Pitch is the angle at which the roof rises. This may be expressed in a number of ways such as a ratio, percentage, but I prefer degrees. The picture above illustrates the necessary components to work out the degrees of the pitch. As shown, the pitch may be calculated by working the formula in this example:
Pitch = tan-1(rise/run)
Rise = 3m
Pitch = arctan (rise/run)
P = tan-1 (3/10)
P = tan-1(0.3)
P = 16.7 degrees
So the pitch in the above example equals 16.7 degrees, which, for a pitched roof is only relatively gentle. If you are not into Pythagoras or mathematics, you may like to use an instrument or a levelling app to do the work for you.
Generally speaking, if the roof pitch is greater than 5 degrees (>5) than you can use virtually any roof sheet you prefer. If the roof pitch is less than 5 degrees, you will need to use a profile which will be suitable for a 'flat roof'. If you are not sure what profiles look like for a flat roof you can check out the link to Revolution Roofing's profile list here
The next consideration is the amount of 'traffic' or 'load' that the roof is needing to support. Different sheeting is designed to support different amounts of load, so, you may need to check the number and size of the purlins and beams in the roof structure to ensure weight loads and engineering requirements are met given the purpose of the roof.
When putting a roof on a pergola, the purlins and beams are typically visible. Some roof sheet profiles can span longer distances without the need for support from purlins, reducing the 'busyness' of the finish (V-Dek from revolution roofing is a good example). Such a roof sheet is not designed to take load or 'traffic'.
Sometimes a profile may be available in different base metal thicknesses (BMT's). The BMT plays a part in the strength of the sheet. The higher the BMT the stronger the sheet,.
The final look of the roof may be the most important decision for you. We live in world where looks matter. Your roof is not only functional but more importantly adds value and style. While colour makes an obvious impact, texture and style have a part to play. The roof can impact the look of your building by as much as 50% adding value and street appeal. Despite the different styles available, in my opinion unless you have a uniquely designed building or require 'flat' roof sheeting, it is safest to stick with a corrugated profile.
Most roof profiles can be ordered in a painted or a plain finish. Bluescope steel is my go to metal manufacturer and they have a couple of great products which can be folded into roof sheets namely, Colorbond and Zincalume. If you are not sure of which finish would suit your home best, check out my post (Colorbond or Zincalume: Which should I use for my Roof).
Which roof sheet profile should be used will generally come down to pitch, but it is good to know that outside of that limiting consideration you DO have choice. Not only in colour, but style and strength. If you have been speaking with roofing contractors who are not offering options, you may like to speak to someone else.
If you live in South Australia or you would just like some advice, please reach out. I am happy to help.