Reroofing question

My cabin needs a new roof. We want to put on a metal roof. I have been told that a metal roof can be installed directly over the old shingles.
My manner of doing things tells me that the shingles should be removed first, then the new roof put on over new paper, etc., on a flat surface.
Yet, I have heard of many people putting one layer of roofing upon another, sometimes with quite a buildup.
Who's right? Take the old shingles off, or roof over them?
Steve
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Steve,
It is possible to put new shingles over old on many roofs. Probably possible to put metal roofing over shingles as well. Taking off the old shingles will allow you to assess the roof deck and replace rotten parts. You really need to have a roofer come out and look at your roof unless you can tell whether the roof will support the weight of the metal roof and whether the roof deck needs work.
Dave M.
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Both. Depends on the situation. If you have a lot of broken or curled shingles, or more than one layer, take them off. Do you know the condition of the deck? If not, take them off.
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Steve B wrote:

pros: steel might lay flatter. can fix any deck problems. no need to worry about weight of multiple layers if your roof is underframed.
cons: stripping shingles and disposing of them is a lot of work.
you can go over the old, but if it was mine, i'd tear off the shingles. there is no one right answer.
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Steve B wrote:

I'd like to add to the answers you've gotten so far, did you know the metal roofing will not be nailed directly to the old shingles or the roof. They put down runner strips that run up and down so far apart that will leave a slight air gap between the existing shingles or roof. That's what the metal roof is nailed onto.
J
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On Sun, 21 May 2006 15:27:20 -0700, "Steve B"

Doesn't matter what we guess, you want to even see if you local codes allow for two layers. I've been told some areas of the country do not allow this, for cosmetic and fire reasons.
Afte checking codes, around us metal roofing is still a scarce service, so out local guys are typically 'certified' by the manufacture, you can ask them too.
imho,
tom @ www.FreelancingProjects.com
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