Plywood thickness 1

[E Ward]

I have a building going up that has mostly 24" oc rafter spacing. because of the span, one section / plane, of the roof has an increase in LVL size from 1 2/4"x12 to 1 3/4x14, with a decrease in the spacing to 16"oc. The sheeting that has been spaced is 3/4" osb or plywood for the whole job. I have a stockplie of 5 ply 5/8" plywood that has no span index stamped that is readable. Can this material be used for the sheeting? My engineer, who happens to be the plan checker for the County is on vacation until the first of Sept. I'd like to get the roof sheeted before that. Any help?
Thanks, Eric

 

[phamENG]

If it has no readable span index I would not allow it without a detailed review. And then only if it had been stored adequately. Sitting in a yard or even under a carport? Hard pass. If it was inside a warehouse I could get on board with it if it's provenance can be established.

 

[SWComposites]

If 3/4 sheeting is spec'd on the drawing, why would you think 5/8 sheeting would be acceptable? its a lot more flexible.
And since when is this site for contractors to ask random internet engineers if various substitutions are acceptable?

 

[E Ward]

Thanks for the quick response. The material was the old roof sheathing. It is 45 years old but looks a feels at least as good as the new material. Your thoughts?

 

[phamENG]

My thought is no. Unless you had an architectural conservator painstakingly remove each nail with a pair of tweezers, it's probably damaged more than would be acceptable. The work that's being done needs to provide an extended service life to the building. It may not seem like much now, but trying to push plywood to 100 years after damaging its edges is not going to pan out in the long run. Just use what what was spec'd.

 

[WinelandV]

Is 3/4" @ 2' o.c. equivalent to 5/8" @ 16" o.c.? Possibly, it's hard to say. While we are engineers, we are not the engineer whose seal is on the drawings. We can give an opinion, but ultimately you'll be at the mercy of the engineer.

To boot, assuming that the 5/8" thick you have on hand is rated for this application, it's 45 years old. I would be hesitant to approve that substitution.

An aside, on my jobs I prefer the chance to evaluate a request for substitution, as opposed to being told a substitution was made and could I sign off on it. It's similar to going to a restaurant, ordering a New York Strip, but getting a ribeye brought out to you - "turns out, we're out of the New York Strip, so we did this instead". Yeah, you could send it back, refuse to pay, etc, but you'd rather not be put in that position to begin with.


Please note that is a "v" (as in Violin) not a "y".

 

[phamENG]

"turns out, we're out of the New York Strip, so we did this instead"

You must work with some great contractors. I usually get shoe leather in lieu of my NY strip....

 

[WinelandV]

For the purpose of my illustration, I thought it best to at least be somewhat equivalent.

Please note that is a "v" (as in Violin) not a "y".