New Roof Shingles

larrylwillDecember 15, 2009

I bought a house 2 years ago, it is a 60's rancher. The pitch is low maybe 4x12. I believe the current shingles were put on in 2000 or 2002. They are 20 year 3 tab. I am on a bluff and the winds get high at times, 25-35 with gusts to 45 or so. Since I moved in every strong wind storm bends back and breaks tabs off. I have noticed that many tabs were not stuck to the next shingle, I have also noticed that they seem to get debris under the tabs witch prevents them from sticking. The ones that are stuck down seem ok. I have been putting roof cement under the tabs of the ones I find not stuck.

I am thinking about a new roof with 30 year single tab shingles which look like these. They are 140mph rated and about 2x as heavy as the old ones.

The roof sheathing feels like 1/2" plywood and is a little wavy in places.

Although the underside looks good. I know the best thing to do would be remove the old shingles and re sheath it with 3/4" plywood.

My question is: If I just re shingle over the existing shingles just how would it affect the life and wind resistance? If I get 25 years out of them I would be 90 so I don't think I would still be in this house.

Opinions please.

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Putting new shingles over old ones is never a good idea - especially since you're in a windy area.Some manufacturers also void their warranty if the shingles are installed over old ones. Shingles rated for high wind areas should help. You may also be better off with "organic" shingles rather than fiberglass ones, assuming this is what you have. Fiberglass has a greater tendency to break rather than flex, especially in cold weather. The tabs of shingles are not intended to stick; the cement is in a line just above the slots between tabs. This is where they are nailed.

    Bookmark   December 20, 2009 at 5:32AM
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"The roof sheathing feels like 1/2" plywood and is a little wavy in places"

If severe enough, that's causing areas of the shingles to get "pockets" allowing winds to get up underneath and roll them up and off. If you insist on recovering over the old, put a barrier of 30# saturated felt between the two as the existing shingles will draw the oils out from the new shingles if not felted. As stated above, the best route to take would be to pull the existing, skin over with another layer of sheathing, and shingle away. Dimensional/architectual shingles do better than standard 3-tab shingles in high wind areas. Doing it right will be better for re-sale or for whoever gets your home when you are done with it. Pay more now or pay worse later.

    Bookmark   December 20, 2009 at 1:23PM
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