Bumps on a new roof


Old 09-05-12, 09:47 PM
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Bumps on a new roof

I have a new roof installed around almost 2 months ago. The new roof is made of Certainteed 3 tab shingles. After it was done I realised there weree some bumps on the roof. My contractor told me this is not a problem and that bumps would flat it out in a couple of months. After almost 2 months the bumps are still there, even in the hot summer of Missouri. I was looking at other new roof son my subdivision to see if they have those bumps too. There are many new roofs because we had a strong storm that damaged a lot of houses. I found no new roof with bumps. Now I am just wondering if I should pay the contractor the remaining part of the bill or if I should ask him to fix it before paying it. Would somebody share your knowledge and let em know if what the contractor told me is correct?
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Old 09-06-12, 05:47 AM
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Much depends on what is causing the bumps. It could be the structure or sheeting underneath, a ripple in the tar paper or shingles installed properly. If you could post some good pictures of the roof it would help determine what's going on.
Old 09-06-12, 06:16 AM
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Old 09-06-12, 08:13 AM
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Is this a re-roof over an existing roof or did you do a tear off of the old roof first? - Some places do not allow a new roof without a tear off because that allows access to correct and sheathing problems.

Old 09-10-12, 01:24 PM
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was the roof hand nailed or was a nail gun used?

A nail gun pressure has to be adjusted to make sure you don't under or over drive the nails. If a roof is old enough and the sheathing was poorly ventilated it will get spongy so when you nail into it it tends to take more pressure to set the nail properly. If you adjust your gun for this condition and then you drive a nail at a stiffer part of the deck like at a rafter or truss then the pressure will drive the nail head right through the shingle. Therefore the contractor backs off the pressure and some nails don't get set at the spongy areas between the rafters.

I would guess this was a re-roof with a nail gun and you have nails not fully set inbetween the rafters but I can not be sure. Pictures both overall and close-up would be good.
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