Old 06-14-03, 09:54 AM
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I need to replace my roof. The contractor said the roof is OK (no hail damage, leaking, etc.) but it is 28 years old and wearing "thin." The contractor (this guy seems very professional and strikes me as being honest) also said the roof deck feels strong everywhere and does not "give" when walked on. When I got the estimate he figured in a tear off. My question do I need a tear off? What are the advantages and disadvantages to tearing off verses not tearing off? It is a standard gabled asphalt roof. Also what are the advantages to using "Three Tab 250lb. shingles" verses "Shake 235 lb. shingles?" Any help would be much appreciated. Thank you. Ed.
Old 06-14-03, 12:16 PM
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Your contractor sounds more honest than most. The one point I question is why he is doing a tear-off. You do not mention having more than 1 layer currently, and most zoning regulations allow at least 2, most allow 3 layers. The benefit of removing the old roof is weight reduction, but should not be a problem to leave it there.
One problem with most people doing their own roofing is getting straight lines. With the old shingles to go by, this is not much of a problem. Check the price difference of buying the shingles and nails to do it yourself. Also, most building material outlets have trucks which can unload the shingles onto the roof for a few dollars more. This is usually worth the price to not have to carry dozens of bundles up a ladder.
Old 06-15-03, 08:17 AM
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Thank you very much dragongate for your reply. I appreciate the info. One question I still have; what are (if any) the specific disadvantages to roofing over an existing roof? Does it look as good? As far as advantages, does having more than one roof layer enhance the insulation properties of the structure? Can you still install gable vents when putting on one roof layer over another? Thank you, ELS.
Old 06-15-03, 04:59 PM
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Disadvantages to a roofover.
First, the old roof needs to still be flat. In other words, if the old shingles are curled, etc., the new roof will not lay flat, which would make it necessary to strip the old roof.
The only other thing which comes to mind is the previously mentioned weight. This should not be a problem. If there were some sort of structural problem which would make this a consideration, you would have seen other problems by now.
In appearance, there is virtually no difference. The only part that is visible is if you look closely at the end, it will be twice as thick.
Insulation value is virtually nil.
Not sure what you mean about the gable vents, as the gable is the triangular part of the vertical wall at the end of the roof.
If you are referring to roof mounted vents, yes, they can still be used. If you are planning to do this yourself, get advise from someone knowledgeable at a building material center. This way they can show it to you with the parts in hand to make sure it is clear, with no misunderstandings. Do NOT be afraid to ask what might seem like a silly question. It is much cheaper than fixing a mistake.
Hope this helps.
Old 06-15-03, 07:46 PM
bungalow jeff
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I recommend the tear off. You will never get the same life out of a new roof that is placed over an existing one, and you will have to tear off two layers that much sooner. Structural problems will remain hidden and some manufacturers will not warrantee a roof over. You are hiring a pro who can easily lay shingles in a straight line and will not need the existing roof for a guide. If that were done, any lines that are slightly off are exaggerated through the second layer, and it will not look as good.

The heavier shingles will wear better than the lighter and resist wind better.

Gable vents are on the gable ends of the house and are not on the roof. The switch between gable vents and soffit/ridge vents brings the attic/roof insulation into the picture.

Your contractor has given you good advice. Hopefully, some of the regular roofers/moderators will chime in too.
Old 06-15-03, 07:54 PM
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Roofovers are not recommended. Doing so will cover over any problems that you have. Addressing future problems will require cutting through roof layers, if you are lucky enough to locate the leak. Have existing roof removed and new flanges installed around vents and other openings in roof. Protect the investment in your home and don't take short cuts that can run into $$ later. When it comes time to replace the roof again, you will be charged extra for removing two roofs. Do it right the first time. A job worth doing is a job worth doing well.
Old 06-15-03, 08:19 PM
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Tear it off.
You're only asking for problems if you don't.
You may not have a leak now, but it is likely that you will have inherent moisture in the roof system that you will be roofing over.
Manufacturers frown upon that.
Better to spend a little more now than a lot more later.
It is rarely, if ever, recommended to do a "roofover".
I agree with Bungalow and Twelvepole.
Tear it off.

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