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Not so visible in photos because of the way the sun hits the roof but very visible by naked eye. Enough for my neighbors to stop by to ask me what's wrong. I had the new roof installed 2 weeks ago and the dipping effect was visible from first day. I spoke to the company that installed the roof and after sending over one of their production managers the told me that the job was done correct but my plywood under the shingles has buckled. I told them as we signed the contract that any damaged plywood can be replaced at my cost, but they say the plywood was not damaged only warped. The house is 16 years old. I have labor warranty with company. What should I do?

  • Can you inspect it from inside the attic?
    – Mattman944
    Oct 15, 2019 at 17:13
  • Yeah the plywood does not look discolored but several of the Hclips are compromised leaving the plywood uneven
    – Jagro
    Oct 15, 2019 at 17:24
  • Was the roof exposed to rain while the job was being done? Are you sure this is a new development? Plywood or OSB? OSB sheathing is subject to swelling when it gets wet. My guess is that it did during initial construction and you just haven't noticed until now.
    – isherwood
    Oct 15, 2019 at 18:43
  • I just bought the house a year ago so I haven't seen original placing of roof . On the day of replacement the weather was nice and sunny . Not even a drop. But even if it was from the original construction, when they stripped off the old shingles and the plywood was bear should they not have seen sagging plywood and replaced?
    – Jagro
    Oct 15, 2019 at 18:46

1 Answer 1


I had a similar issue on a house (built in 1973) that had 3/8" plywood for roof sheathing. Over the years it tended to bow downwards, leaving an odd look from the curb. To solve it, I cut multiple 2x4 stretchers that fit between the trusses and boosted the plywood even.

You didn't say if it was a truss roof or rafters, but the solution should work the same either way. You could install the 2x4 stretchers at the joint of the sheathing and it should level the roof out. I will say that unless you have good spacing in your attic, it will be a practice of straddling the trusses and getting in to tight spaces.

  • 1
    I just got off the phone with the roofing company and they suggested exactly that. Plenty attic space so they will come and try the 2×4 wedges to lift the roof from inside out. They told me it's under the warranty so it won't cost anything to me. Thank you for respond
    – Jagro
    Oct 15, 2019 at 18:42
  • 2
    Do not let the roofing company use 2x4 wedges of any kind. What you want is full 2x4 dimension blocks cut to the exact length as the space between the upper members of your rafters. These are then inserted in between the rafters so the top of the block is flat to the roof's under surface. You then nail through the sides of the rafter into the ends of the blocks. Typically you can stagger the blocks from rafter to rafter so you can nail each block easily from each end. In the case where you are placing blocks under the plywood seams you will not want to stagger those blocks. (continued)
    – Michael Karas
    Oct 15, 2019 at 21:28
  • (continued from above) When the blocks are aligned from rafter to rafter it is typical to toe nail one end of the block where direct access to the end of the block is covered by the previous block.
    – Michael Karas
    Oct 15, 2019 at 21:41
  • wow. 3/8" is incredible. I got lots of raised eyebrows on the house I just built because I insisted on 5/8 PLYWOOD--NOT OSB for roof decking. I sleep easier with that decision. I hate OSB.
    – peinal
    Oct 18, 2019 at 13:22

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