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?
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.
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.
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.
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.
tom @ www.FreelancingProjects.com
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