# R503.2.1.1(1) code on roof sheathing thickness



## atvjoel (Nov 26, 2021)

Am I reading it right that if I have 60psf snow load in my area (thats what trusses are engineered for), I could not use 7/16 osb because that only allots 40psf with 24" O.C?

I would have to use 15/32 plywood they dont sell 15/32 osb where I am at, or 19/32 OSB?

I will probably go with 15/32 plywood if I am reading this right.

Thanks in advance.


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## e hilton (Nov 26, 2021)

Can yo7 do trusses at 16” and use the lighter sheathing?


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## atvjoel (Nov 26, 2021)

e hilton said:


> Can yo7 do trusses at 16” and use the lighter sheathing?


Trusses are already up, I am ready for sheathing today after I get my other overhang built


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## bill1952 (Nov 26, 2021)

I read span tables same. 7/16" tops out at 40 psf when on 24" centers.  15/32" which tops out at 65 psf on 24" centers.

If you own and can't or won't return 7/16, strap trusses with furring 20" on center.  I'd think 1x3 would be adequate for furring but not sure.


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## e hilton (Nov 26, 2021)

atvjoel said:


> Trusses are already up, I am ready for sheathing today after I get my other overhang built


A little late to be asking the question …


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## steveray (Nov 29, 2021)

e hilton said:


> A little late to be asking the question …


Not too late.....Sheathing isn't nailed down yet....


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## e hilton (Nov 29, 2021)

steveray said:


> Not too late.....Sheathing isn't nailed down yet....


True … but if he is expecting to install the sheathing “today” … the day he posted the question … it’s a little late to be realizing the material he bought won’t work.


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## tbz (Nov 29, 2021)

e hilton said:


> True … but if he is expecting to install the sheathing “today” … the day he posted the question … it’s a little late to be realizing the material he bought won’t work.


EH,

At least he was smart enough to double check and correct the issue before making it more than just a delay and then pull off and do over.

Joel, I for one give you credit for the catch and looking for a correction and the fortitude to post again.

I also don't know the exact cross strapping pattern nor sizing allowed, but hopefully a call to the truss company or someone who knows at your supplier or maybe someone here can provide a table specific pointer which provides the direction. 

The obvious was getting the correct plywood, but it looks like that is not available from your local suppliers, thus the outreach and question.

Good luck


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## atvjoel (Dec 1, 2021)

e hilton said:


> True … but if he is expecting to install the sheathing “today” … the day he posted the question … it’s a little late to be realizing the material he bought won’t work.


I didnt say i was expecting to do it that day. I work at a remote Mine Site and have to leave for weeks at a time. I meet my project milestones as much as possible.


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## atvjoel (Dec 1, 2021)

tbz said:


> EH,
> 
> At least he was smart enough to double check and correct the issue before making it more than just a delay and then pull off and do over.
> 
> ...


They happened to sell 15/32 plywood (not OSB) at my local HD. My wife is just listing it on FB today for a couple bucks a sheet less. I will just have Home Depot deliver 15/32 plywood. I would even go 5/8 OSB but its substantially heavier and due to being on hillside lot a zoom boom or man basket isnt an option on one side. I might email my engineer thatstamped my trusses and see what he thinks. I am stuck in remote Alaska for next week and a half anyway so i have time.

Thanks for everyones response. It will help people in the future that live in areas with higher snow load then those of Southern US and Hawaii.


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## atvjoel (Dec 1, 2021)

steveray said:


> Not too late.....Sheathing isn't nailed down yet....


Not too late until the shingles are on haha but ya I was not in a hurry to nail it down. Last house i built I went 5/8 but this hillside lot much more challenging and have to manually lift the sheathing up to the roof. Weight is the factor not the extra money. Think I can zoom boom one side but other side way too sketchy, plus there is about a foot of snow.


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## ICE (Dec 1, 2021)

Blocking the edges might be an option.  Whatever the option is, it will be additional work and material.  A few dollars more for plywood makes sense.  If radiant barrier is specified, I don't think that it is available on plywood.


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## e hilton (Dec 1, 2021)

atvjoel said:


> I didnt say i was expecting to do it that day. I work at a remote Mine Site and have to leave for weeks at a time. I meet my project milestones as much as possible.


Well my bad … that’s how i interpreted this statement: _Trusses are already up, I am ready for sheathing today after I get my other overhang built_


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