typical wood roof trusses
typical wood roof trusses
(OP)
I,m in the middle of thinking about floor plan for my new house. I am trying to decide on a great room design, I need to span 30 feet without a support wall. I know everybody going to tell me to go to a truss mfg, and I will when the time comes i just need ideas now. It going to be a typical buildup roof. singles, plywood, a/c ductwork, insulations, drywall, no crawl space or storage. can it be done and how, what size wood.






RE: typical wood roof trusses
You mentioned a typical built-up roof. Does this mean you will have a flat section? You also mentioned shingles and plywood sheathing. Will these trusses support a flat roof section as well as a steep roof section? If so, this will throw a few curves into the truss design. If just typical steep roof (shingles, underlayment, plywood) then pretty straightforward.
RE: typical wood roof trusses
He went by close to the maximum spacing (~24") to save a couple of trusses. Cost him in the long run. He now has cracks in the first floor dry wall. If he had bought the couple of extra trusses and put them on 18" or 16" spacing, he would have been fine. He's happy with the trusses, realizing that the spacing was his fault.
I'd also suggest that you not let the truss bear (even via deflection) on any walls as this tends to crack the wallboard. Put a 1/2" sponge between the top of the wall framing and the bottom of the truss. This will let the truss deflect without imposing any loads on the wall. This lets non-load bearing walls remain non-load bearing. The sponge gives you something to "mud" and paint.
Good Luck,
Imagineer
RE: typical wood roof trusses
There are companies in Southern California that specialize in wood truss calculations, for a fee. Usually the truss manufacturer will provide these for free if you purchase your trusses from them.
David Allee, Architect
darct@tfb.com
Professional affiliations include International Conference of Building Officials and Light Gauge Steel Engineers Association.