I'm building a triangular pavilion that will be 18x24x30ft with a 1 foot overhang. The roof will be corrugated metal and the wood will be western red cedar. The posts will be anchored to concrete footings that are already poured (24 inches deep below the frost line).

I live in Portland Oregon where the snow load is "20 psf + 5 psf rain on snow surcharge".

What I want to know is,

  1. what size posts do I need to use if I use three posts (one in each corner of the triangle)?

  2. what if I have six posts (with a center post between each of the corner posts)?

  3. what if I do a pole-barn style build? how large would the poles need to be?

  4. finally, is there some way for me to figure this out on my own? I keep coming up blank but maybe I just don't know the right search terms.

  • It is the number of posts and the size of wood/steel beams you want to use that are important. The greater the span between posts, the greater the size of the beams. Post size you probably want 6x6 at ~10 to 12 foot spacing.
    – crip659
    Commented Aug 6, 2023 at 11:57
  • 1
    Aside: The wind loading on an open pavilion is likely to be rather different than an enclosed structure.
    – HABO
    Commented Aug 6, 2023 at 13:33
  • @HABO Good point. The uplift force can be strong so OP will need good anchors.
    – crip659
    Commented Aug 6, 2023 at 14:48
  • Usually your building department will have recommendations on what is required.
    – crip659
    Commented Aug 6, 2023 at 16:32


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