OSB Roof Decking Thickness - 7/16", 1/2", Or 5/8"

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Old 08-07-2011, 08:13 PM   #1
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OSB Roof Decking Thickness - 7/16", 1/2", Or 5/8"

Currently we space rafters 16" oc and use 7/16" OSB with H clips. We're in Dallas so we don't engineer for tremendous live loads for an asphalt shingle and we feel comfortable with 16" oc rafter spacing and 7/16" OSB decking.

I'm contemplating upgrading to 1/2" or even 5/8" OSB though to reduce roof sag hopefully to nil. We get snow from time to time, especially the last few years. We actually got a good accumulation of snow on the roof a few times. I'm see very minimal sag from time to time and want to cure that being a perfectionist. I'm considering what the additional cost is and whether it's worth the added expense.

Any input on whether the added thickness will help roof sag or should we go to 12" oc spacing. I'm thinking either way will cost quit a bit.

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Old 08-07-2011, 08:17 PM   #2

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Re: OSB Roof Decking Thickness - 7/16", 1/2", Or 5/8"

Keep the 16" oc, go with 1/2" osb, and add an extra clip in each space. Very economical upgrade.


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Old 08-07-2011, 08:37 PM   #3
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Re: OSB Roof Decking Thickness - 7/16", 1/2", Or 5/8"

if were using osb we get 9/16, we dont worry about getting both 7/16 and 9/16 for walls then the roof, we just get all of the same.. this way no worrying about grabbing scraps to fill in small spots and not having the correct thickness.

most our truss packages come as 24" o.c code only calls for a single H clip between trusses but we do 2 per spacing to give it extra strength
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Old 08-07-2011, 08:53 PM   #4
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Re: OSB Roof Decking Thickness - 7/16", 1/2", Or 5/8"

7/16" wall sheathing. 1/2" for roof sheathing. We get snow loads though.

I've never heard of 9/16" sheathing.
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Old 08-07-2011, 09:30 PM   #5
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Re: OSB Roof Decking Thickness - 7/16", 1/2", Or 5/8"

1/2" is standard for 16oc around here, but I prefer 5/8" upgrade. I also like Warrens suggestion
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Old 08-07-2011, 11:45 PM   #6
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Re: OSB Roof Decking Thickness - 7/16", 1/2", Or 5/8"

Our choices are 7/16 or 23/32. We get a fair to middling snow load here in central PA, and the 7/16 seems to do just fine on 16" centers.
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Old 08-07-2011, 11:50 PM   #7
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Re: OSB Roof Decking Thickness - 7/16", 1/2", Or 5/8"

We use 7/16 on a 2' OC with no snow load and use H clips
We use 5/8 on a 2' OC with no snow load and no H clips


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