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This may be a simple no-brainer for most members here...

I will be (re)roofing my small ranch home this spring. It currently has 3/8 sheathing that has sagged in some areas, and the "STAPLES" holding it down have let-go in others.

My simple question is...
can I just install 7/16 OSB over the exsisting sheathing? :eek: There have been no leaks or signs of rot on the current decking. (7/16 OSB because I have a 30 day price at 7.90 per sheet.)

TIA for any replies.
 

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Check with your local building code most cities will allow you to install new decking over existing. Grumpy is right it would be better to tear off old decking and install new 1/2 inch decking. I prefer OSB i will probably be one of the few that does on this message board. OSB won't warp, separate, or crack as easiely. It will swell up if exposed to moisture.
 

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The way I see it, I would not lay another thin ply over a saggy thin ply sheet. You may end up with two thin saggy ply sheets. I go with Grumpy. I like 5/8" CDX it is currently less costly than 1/2".
 

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Stumpbuster, follow the above advice. I've never heard of 3/8" roof sheathing. Going over it will create voids and potential future problems.
 

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Teetorbilt said:
Stumpbuster, follow the above advice. I've never heard of 3/8" roof sheathing. Going over it will create voids and potential future problems.
Good advice, as the voids can be super heated dead air space and ruin the integrity of the substrate.

If the rafters are 2' OC, go with 5/8" sheathing. If they are 16" OC, then 1/2" is ok. 3/8" is acceptable over skip sheathing, but I always use 7/16 OSB.

Best regards
 

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3/8 roof sheathing is acceptable by the BOCA 98 building codes. Actually the building codes discuss span ratings and not thickness of materials. 3/8 is soft as hell. There was a job I lost because I refused to re sheat a the roofs with 3/8.

DO it right or don't do it at all.
 
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