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Community and Q&A

Roofer put new 1/2″ OSB over old 1/2″ OSB

hubbhunter | Posted in Building Code Questions on

I recently had my roof replaced but have not paid the final bill. My roofer called me yesterday to advise me the entire north side of my house was going to need all new OSB installed.

When I showed up 2 hours later the new OSB had already been put on (which I thought was extremely fast). Last night I went into my attic and noticed I could till see all the old original OSB. Turns out, all he did was put new OSB over top of the old 1/2″ OSB that was already there. There was no water damage but there was dry rot and poor ventilation because no ridge vents had been installed originally.

My question…. Is this considered up to code? Is this actually going to fix the structural integrity of roof since he is putting new OSB over old shotty OSB? Also, i’m upset because in my original bid he states I am responsible for $40 per sheet of replaced OSB. Key word is replaced. He didn’t replace anything technically, only went over top? What should I do?

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  1. GBA Editor
    Martin Holladay | | #1

    This is hard to judge from the information you provided. We'd need to know how extensive the rot is, and how advanced. (You might be able to determine that from the attic).

    Going over the old OSB isn't necessarily a problem, as long as the rot area was small and the rot was not advanced. That said, if the rot area was small and the rot was not advanced, one might have expected the roofer to remove and replace just one or two sheets of OSB instead of re-sheathing the entire north side of your roof.

    It never hurts to call up your local code enforcement official to ask what their office expects.

    -- Martin Holladay

  2. hubbhunter | | #2

    Talked with the roofer, he stated no rotting wood but the plywood was delaminated and that's why they went over it with 7/16 OSB. For my area a permit is not needed to tear off and add shingles. It is required to replace OSB, he didn't replace, just went over top and I'm not sure if that's his way of avoiding the permit requirements. I'm not able to speak to anyone to confirm currently

  3. user-6184358 | | #3

    If the original plywood is bad, the new sheathing needs to be nailed per code to act as the new roof diaphragm to properly distribute and resist the forces placed on the building. Building inspectors usually want to inspect the nailing.

  4. hubbhunter | | #4

    It's a cape cod, so unfortunately the entire roof isn't accessable from the crawlspace/attic. Im waiting until Monday to speak to the code enforcement to see if a permit should have been pulled for the new OSB. But, my concern is the bad plywood underneath should have been torn out vs gone over, in my opinion

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