new sheathing on top of old?

10-30-2009, 05:51 PM	#1
tns1 Member   Join Date: Jun 2009 Location: San Diego, CA Posts: 180	new sheathing on top of old? When I redo my asphalt shingle roof, I'll be stripping it first, and then I'll need to replace an unknown amount of sheething. If it turns out that most of it needs to be replaced, would I be advised to remove all of the old stuff or layer on top?

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10-30-2009, 06:13 PM	#2
jogr Member   Join Date: Jul 2007 Posts: 1,463	new sheathing on top of old? I'd remove the bad to make sure the deck is fllat and secure.

10-31-2009, 01:19 PM	#3
tns1 Member   Join Date: Jun 2009 Location: San Diego, CA Posts: 180	new sheathing on top of old? I guess what I was wondering is if layering new osb on top of my existing plywood would even be permissible from a load standpoint. Are the load calcs based on what the framing will bear or just what the sheething will bear?

10-31-2009, 06:48 PM	#4
BamBamm5144 Member   Join Date: Oct 2009 Location: Wisconsin Posts: 132	new sheathing on top of old? You will have to check with your local building codes. From an added weight standpoint, I would assume it to be against codes. I have never done it like that but I usually rather do things right the first time.

11-01-2009, 07:31 AM	#5
Slyfox Residential Roofer     Join Date: Jun 2008 Location: Struthers, Ohio Posts: 803	new sheathing on top of old? If you replace any bad / rotted sheathing with the same type, than cover over all with a lighter weight / thickness you should be fine. But that's assuming there's no structural damage, bad trusses, etc. You do not want to cover rotted lumber with new tho. __________________ God Family Country Work Play To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

11-01-2009, 11:28 AM	#6
ausblake Member   Join Date: Aug 2009 Location: Seymour, TN Posts: 41	new sheathing on top of old? Agree with Slyfox. You never cover bad wood with good wood. Tear up the bad and replace.