I have read through posts on Byggahus and various websites like Svenskt Trä and Moelven. The latter used to have a dimensioning program, but it's apparently removed!?
I have an extension where I need to calculate which roof beams I need. The span is 4.3m (in one section) and the slope is 20 degrees, and it concerns snow zone 1.5. The CC will probably be 1200. The roof will be metal from, for example, Byggmax.
I'm studying the handbook for Svenskt Trä, but I miss the feature to calculate the dimension of the beams based on the roof pitch. The handbook specifies a maximum pitch of 5 degrees, but I want at least 20 degrees.
At Svenskt Trä, I arrive at the dimension 70x220, but then the roof pitch is a maximum of 5 degrees. What roof beams do I need and is there any program where I can calculate it myself? Or use a formula and calculate manually?
I have an extension where I need to calculate which roof beams I need. The span is 4.3m (in one section) and the slope is 20 degrees, and it concerns snow zone 1.5. The CC will probably be 1200. The roof will be metal from, for example, Byggmax.
I'm studying the handbook for Svenskt Trä, but I miss the feature to calculate the dimension of the beams based on the roof pitch. The handbook specifies a maximum pitch of 5 degrees, but I want at least 20 degrees.
At Svenskt Trä, I arrive at the dimension 70x220, but then the roof pitch is a maximum of 5 degrees. What roof beams do I need and is there any program where I can calculate it myself? Or use a formula and calculate manually?
Hello, the dimensioning is still available. Check here:
https://www.byggbeskrivningar.se/dimensionering/nockbalkar-och-takasar/
https://www.byggbeskrivningar.se/dimensionering/nockbalkar-och-takasar/
There are a few different options to choose from. This one might fit better? https://www.byggbeskrivningar.se/dimensionering/pulpettaksbalkar-och-balkar/
The design roof load decreases with increasing roof inclination. The dimensions applicable for 5 degrees will never be too weak for 20 degrees, albeit at the price of slight overdimensioning. Otherwise, you can multiply the roof load you have calculated with the cosine of the angle to get the factor you should use. Cosine 20 degrees is about 0.94. Then it depends on how much deflection you can accept or if you should design with respect to the breaking limit. If you want the deflection to stay under 1/300 of the span, 70x220 C 24 (alternatively glulam 56x225) is required, otherwise 45x220 C24 is sufficient. It's not always that the differences in conditions are evident from the various apps.