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Ask-The-Experts > Installation

Over Shingles? Or not?
I have several questions and maybe they can all be answered. First.....I now have heard there are two types of metal roofing...one that leaves screws exposed and one that has them hidden. Is this the case? If so, which is preferred and why? Bubble wrap or not? Over existing shingles or not? Why? I have a three skylights, is it easy to install metal using existing skylights? I have been told that I will need to replace them. They don't leak, and am afraid replacing will cause them too do that very thing. What about venting? I have a 28 x 70 Double wide mobile home. I know this is many questions and I thank all ahead of time in addressing them.
There are indeed exposed and concealed fastened products. Most folks will say that concealed fasteners ultimately are better but I am a believer in all metal roofing. Skylights present a challenge to all types of roofing but metal can be flashed around them. Going over old shingles is possible in many cases. I really would suggest contacting an experienced metal roofing contractor or supplier and having them take a look at your home and help with the other questions. There are so many variables. Feel free to call me at 1-800-543-8938 ext 201
We have a 20 year old shingle roof that most of the gravel has washed off. These are dimensional shingles so they are not flat. Wht would be the down side to putting the metal panels over the shingles? Is it becasue they are not flat? I would love to not have the clean up or have these shingles end up in a land fill. Do they rot or cause problems over time under the metal? I have read different opinions about installing the metal over shingles. I would appreciate your comments.
Many residential metal roofs are installed over old shingles. Every case must be considered individually and there are some differences based upon the type of metal roof that is being installed but this is done on a regular basis with no ill effects. The low weight of metal roofing encourages its installation over old shingles. Additionally, the design of many metal roofs, especially the heavier shingle profile metal roofs, encourages this practice as well. I do feel that in all cases underayment should be installed first over the old shingles.
We are considering installing metal roofing over the existing asphalt shingles that are over 30 yrs old. Could you please tell me the pros & cons other than saving for the tear off & clean-up.

Frank H
We have been advised by one roofer to go over our shingles. And that our skylights can simply be caulked around. Another roofer said it is a must to remove shingles and he wouldn't touch our job if we wanted them left. Also as for the skylights he said NO WAY to just caulk around. He said they needed to be removed totally and either replaced or just left out. He also said we could use a clear panel where the skylight was. Any ideas on this?
Alma, it would be helpful to see photos of your current roof and of the skylights. It also would be helpful to know exactly what type of metal roof you plant to install. Generally speaking, though, many metal roofs do install over the existing shingles. Additionally, though, skylights need to be flashed around, not just sealed (caulked) around. I hope this helps. Should you wish to email me photos and additional info, please do so at todd@asktoddmiller.com
I already asked if you could put a steel roof over existing shingles but I neglected to say 2 layers of shingles. Is the answer still that it would be fine?
Metal roofs, due to their low weight and design, are installed over multiple layers of roofing. However, each job must be evaluated on its own. Very uneven roofs can affect how the metal roof lays. Building codes in some areas may not allow three layers. If there are existing leaks or other bad areas, those should be addressed. In reality though a metal roof probably isn't adding much more weight than your last layer of roofing lost due to oil evaporation and granule degradation.
I am considering replacing my 20 year old roof with a metal roof but have a couple questions. With existing ridge vent and electric exhaust fan will I be able to keep both or should I consider gable roof vents with a fan in one end? Thank You
Most metal roofs have ridge vent options. A great way to vent passively is with continuous intake vents in your soffits and a continuous ridge vent for exhaust.

If you are going to be investing in a new and permanent roof option, update the soffit venting and combine that with a proper ridge vent. You won't have to worry about the fan in the future or waste the electricity to run it.


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