"Long" Span Roof Sheathing 1

[T_Bat]

Hey everyone,

I have a small pavilions structure with CFS scissor trusses bearing on steel beams. The contractor has requested we use a thicker sheathing so we can put trusses @ 4'-0" oc. Using 1-1/8" sheathing I can make the numbers work for my loads (wind is 115 mph ultimate and SDC C). However, I've personally never used sheathing spanning this long. I've still got to check the diaphragm capacity but I'm wondering if anyone here has done this or if there are some reasons I haven't yet discovered in detailing the structure that would make this a bad idea. Roof slope is 12:12 and the overall plan dimensions are 20'x20'.

I know this is a general question but I'm just looking for anything I should immediately be looking for for proof of concept.

Thanks!

 

[JAE]

There is plywood with span ratings of 48/24 which represents roof / floor span limits. Usually these are 3/4” thick panels so a 1” plus thickness wouldn’t be a problem.

Check out Eng-Tips Forum's Policies here:
faq731-376

 

[JAE]

Check out Eng-Tips Forum's Policies here:
faq731-376

 

[JAE]

Attached below is a pdf from APA with sheathing span/load tables.

Check out Eng-Tips Forum's Policies here:
faq731-376

 

[XR250]

Don't forget that span adjustments must be made for single span conditions. This usually occurs at some location in the field - especially during repairs. Honestly, I have never done it, but I also try not to max-out sheathing spans.

 

[T_Bat]

Wow - thanks everyone. I've been looking at the APA table. As mentioned, I can show on paper it works - just leaving my standard designs so I wanted some second opinions.

 

[T_Bat]

Just to close this thread - I went with 1-1/8" sheathing at the contractor's preference. We did not want to install blocking at all panel joints. The APA document limits the span of 1-1/8" to 48" without blocked panel edges. It also required 6" spacing on attachment in the field of the panels. Granted that's specifically for wood framing but I'm having them use the same for the attachment to the CFS trusses.

Thanks again for the help!