T1-11 Siding as Roof Sheathing
T1-11 Siding as Roof Sheathing
(OP)
Hi Everyone,
Background:
I have designed a simple patio canopy that is 20'x20'. It's like a deck in the sense that it is attached to the existing house wall framing by a ledger and the joists are attached to the ledger. I currently have the roof designed as 2x6 T&G decking spanning the joists at 12" oc with 1/2" plywood on top. The canopy will be roofed with built-up roofing.
Question:
The owner's architect friend was reviewing the preliminary drawings for him, and now the owner is asking if we can replace the decking and the plywood both with T1-11. Is this feasible?
Thoughts:
The framing will be exposed, so I thought the 2x6 decking would be nice. I added the plywood to provide diaphragm action and to provide a surface for roofing. I don't see an issue with the T1-11 because it is plywood with sufficient shear value for this application. Also, the joists are at 12" oc so the span shouldn't be a problem either. I just wanted to get some other opinions in case I am overlooking something, since I've never seen T1-11 used in a horizontal floor/roof type application.
Thanks in advance.
Background:
I have designed a simple patio canopy that is 20'x20'. It's like a deck in the sense that it is attached to the existing house wall framing by a ledger and the joists are attached to the ledger. I currently have the roof designed as 2x6 T&G decking spanning the joists at 12" oc with 1/2" plywood on top. The canopy will be roofed with built-up roofing.
Question:
The owner's architect friend was reviewing the preliminary drawings for him, and now the owner is asking if we can replace the decking and the plywood both with T1-11. Is this feasible?
Thoughts:
The framing will be exposed, so I thought the 2x6 decking would be nice. I added the plywood to provide diaphragm action and to provide a surface for roofing. I don't see an issue with the T1-11 because it is plywood with sufficient shear value for this application. Also, the joists are at 12" oc so the span shouldn't be a problem either. I just wanted to get some other opinions in case I am overlooking something, since I've never seen T1-11 used in a horizontal floor/roof type application.
Thanks in advance.






RE: T1-11 Siding as Roof Sheathing
Yes you can use T-111 for roof sheathing, just make sure it's at least 5/8" thick to insure you have at least 3/8" left for structural purposes and the grooves run across the rafters. NOW a reality check. How are they planning to fasten the roofing down? If they use nails they need to be less than 5/8" long or you'll get what they call shiners (tips of the nails sticking below the sheathing). Not a pretty sight.
Lonnie
RE: T1-11 Siding as Roof Sheathing
RE: T1-11 Siding as Roof Sheathing
Normally T-111 is placed with the grooves parallel to the wall studs. For strength here, as the roof usage is more likely to see higher load than a wall usage, place the grooves normal to the trusses/rafters and upside down as Ron suggested.
Mike McCann
MMC Engineering