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How Far Will 1/2" Plywood Span?

PostPosted: Sun Nov 18, 2007 11:03 pm
by bdosborn
I'm working through the framing for a standy floor I'm designing and I don't know how far I can span with 1/2" plywood. I would think that I could go 24" but I'm not sure. Anybody have any input?
Thanks,
Bruce

Re: How Far Will 1/2" Plywood Span?

PostPosted: Sun Nov 18, 2007 11:29 pm
by Podunkfla
bdosborn wrote:I'm working through the framing for a standy floor I'm designing and I don't know how far I can span with 1/2" plywood. I would think that I could go 24" but I'm not sure. Anybody have any input?
Thanks,
Bruce

I guess a lot would depend on the quality of the plywood? Nine to eleven ply 1/2" cabinet grade ply is a lot stronger (and flatter) than say, CDX roof sheathing or common A/C plywood from the big box stores. Considering a couple more 2 x 2's wouldn't add any significant weight, I'd prolly go 16" OC or thereabouts?

PostPosted: Mon Nov 19, 2007 3:45 pm
by bobhenry
Span stamp is on the plywood, the 2 numbers are roof span 1st and subfloor span 2nd. This stamp shows 1/2 at 32 / 16 so for floor max of 16"
this will appear a bit spongey if you are a big fellow.

Image

PostPosted: Mon Nov 19, 2007 6:42 pm
by bdosborn
Cool! I didn't know that. Now I wonder how far a 2x2 will span. I hope its 54" because that's how wide my trailer is.

Thanks,
Bruce (who seems to becoming a bigger fellow every year) :oops:

PostPosted: Mon Nov 19, 2007 7:33 pm
by mikeschn
That sounds about right... the dropped floor in the ET was real saggy until I braced it up in the center. Now it's not too bad. I guess my span is about 27" across the trailer, and slightly less fore to aft. That's 1/2" furniture grade birch (not baltic).

Mike...