# T1-11 for roof sheathing?



## DBB (Jul 10, 2010)

I am planning a screened in porch, and considering T1-11 for roof sheathing. I would install such that the plank grooving is on the ceiling side, which will be open for appearance. Is this an acceptable application for T1-11?


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## DangerMouse (Jul 17, 2008)

I don't see why not, it IS plywood, after all.... 
I'd be more concerned, since you'll see the underside, as to what roofing materials you'll be using?
Shingle nails will show beneath if not short enough. I'd consider a rubber sheet roof instead.

DM


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## seeyou (Dec 12, 2008)

I've done similar. As mentioned above, you'll need to add a second layer of regular sheathing (plywood, osb) so the roof nails don't protrude. Even if using a fully adhered membrane, the roof edge must be nailed/screwed.


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## OldNBroken (Jun 11, 2008)

Guess I'm late so all I can say is pretty much what they said. I would definitely do as CU says, double sheet it.


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## Gary in WA (Mar 11, 2009)

Read the stamp on the siding, the left hand number is for roofs (on center member spacing)/ right hand number is for floors. Ask your LOCAL Building Department. T1-11, part of 303 siding group, has the grooves which reduce the shear value (thickness) required for the roof to resist wind and seismic loads. If using 3/8" reduce the shear value to 5/16" which *may not pass *your roof's Inspector. 19/32" thick reduces to* 3/8"*, which will probably pass. But, you will still probably have to double sheath, as mentioned, required for shingle nail penetration through the sheathing, as per Code. (Unless a glue down).

Be safe, Gary


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## Michael Thomas (Jan 27, 2008)

Every once in while you get a post like GNR's which gets me to pause to consider something to which I had previous never given a thought. I like that.


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## Tom Struble (Dec 29, 2008)

i think Gary got it right..as usualt1-11 is a wall sheathing,you need a structural panel over it for the roof


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## the roofing god (Aug 2, 2007)

reality is you need to have the second layer 3/4-1" sheathing so using 1 1/4" nails will not penetrate thru the t-111 ,which should also be 3/4" thickness for this application,,assuming you are going to have a shingle roof installed


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