I have a garage with a roof which has a wooden king post truss that spans 4m ( with a total of 14 trusses spaced 450-550mm apart). Roof pitch is 35deg, and beam dimensions are 38mmx90mm, soft wood I am guessing C16, with modern stamped metal joints.

I was expecting to find a simple table or calculation which would give me the maximum distributed static roof loading which I am expecting to be 0.75kN/m2 but after many hours of searching I am struggling to find anything.

Can anyone point me in the right direction ?

Thanks in advance.

  • $\begingroup$ Aaah the art of safety factors in civil engineering... Reason you may be lacking literature is that 38mmX90mm is commonly referred to as a 2x4. Don't forget to account for the weight of your roofing! $\endgroup$
    – Abel
    Aug 9, 2022 at 0:00
  • $\begingroup$ Thanks Abel, but data on 2x4 doesn't seem to be any better. Really surprised that there are no look-up tables on this, and I have hunted hard. Any references appreciated ! $\endgroup$
    – Marky0
    Aug 17, 2022 at 14:03
  • $\begingroup$ The CivE approach. (Wander the maze some more).. nachi.org/structural-design-wood-framing-home-inspector.htm. Or bypass it and go the mechE approach google.com/amp/s/www.engineeringtoolbox.com/amp/… and model as beams... $\endgroup$
    – Abel
    Aug 17, 2022 at 23:17


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