question – 39′ wide frame over, shallow pitch, super wide valley sleepers
I am getting ready to add some covered patio space to our home. i have engineered trusses coming that will be set over an existing 14’x20′ room, and they will span another 19′ out over our patio to create covered outdoor space. total span is 39′. they will be on 24″ centers headed back to the house. the trusses are only 5′-9″ tall at the peak to match the existing ridge on my home. the trusses is also offset – 19′ one side, and 20′ to the other. the home is a 4/12 pitch. the engineered trusses will be 3.42/12 on the 19′ side and 3.25/12 on the 20′ side. the section over the existing roof will be hand framed rafters to a 1-3/4 LVL ridge board. the rafters will be 2×12 DF for the first 4 becaus of the wide span and shallow pitch. my bottom cuts are going to be around 36″!! that is a super wide valley sleeper, and i am going to have a fortune in 2×12’s laid flat next to each other. has anybody ever used anything else in their projects? maybe some 1-1/8″ subfloor plywood ripped down to width?
Replies
For the part of your new roof over the old one, could you not support it mid-span (in a couple places if needed) instead of a full span?
This might let you reduce the joist depth and make life easier.
You also could talk to your truss supplier about a set of valley trusses.
If i throw a perlin midspan on the rafter, i was under the impression it needed to be resting on a bearing wall (one that connects to the foundation). I dont have any bearing walls available in that area.
i would be a little nervous to have the truss supplier build me some step downs. I measure the existing roof at a 4/12, but it is a 35 year old house and things arent perfect. I feel like my 24" spacing would be compromised trying to keep all of the trusses in plane. Maybe not -- but that would be my luck
Any added loads you put on an existing roof need to be carried to the foundation.
It would be prudent to review the capability of existing roof to carry any extra loads.
Your valley sleepers will spread the new valley end rafter loads to several rafters; an intermediate support could do the same.
You are correct. There is already an over build there that is being wrecked out. I am kind of gambling building the new one as it is definitely larger than existing. Almost twice the size. I think i had answered my own question. If i just use 16" spacing i can use much smaller lumber