Going back with metal roof after our hurricane damage. What's the best method? Remove the shingles? Over top of shingles? Strip with 1x4 or 2x4?
I know somebody on here does roofing just can't remember who....

Is Trox still on here?

Not a guru here but I can tell you that every metal roof that was put right on top of shingles here are about a mile to the north and west of the house it was on. The ones that were stripped with 2x4s and good long screws into the rafters are only 1/8 of a mile away with the rafters still entacted. Just kidding. These roofs were still on the houses. Some had minor damage and some were just fine. My old house was stripped with 2x4s and good screws and it survived Rita and I asked my Godfather( the person who bought it) and he said the roof survived Laura also. I hope this helps you.

I've put a bunch of metal down and never removed the shingles. When I did my roof, straight on top of the shingles. The way I always looked at it was if a big hail storm hit it couldn't beat the metal up as bad having something directly under it. Maybe I'm wrong in my thinking but seems logical.

Download some installation guides from various manufacturers. The ones I read all directly prohibited putting it down on shingles. The thermal expansion scratches the metal underneath causing corrosion. The guides I read seemed to prescribe exactly what marshmud described. That, and placing insulation board in between furring strips (2x4’s screwed to rafters) to displace volume of air that will contain water vapor and condense underneath. The guides also go to a great deal of detail on the screwing patterns around the perimeter (key to preventing uplift and peeling off from wind), and a great deal of detail on the various flashing and sealing. I think even if you are hiring it out it’s a good idea to locate and download 2 or 3 of those product brochures/installation manuals. After educating yourself you can better decide who is a quality installer.

EDIT: BTW depending on how your house is built, finding the rafter centerline at the ridge and eave as you progress across the roof length may not be trivial. The one roof I did was very time consuming because it was not laid out on 16” centers and varied from ridge to eave. I had to probe with screws to establish each rafter and snap a chalk line for each rafter. A professional no doubt knows more tricks than me, but I could see how someone competing on jobs would avoid doing that if possible and the customer didn’t make them.

Good advice. If you are in a coastal region different codes apply for roofing. IIRC, mobile and Baldwin counties started requiring an ice/water shield under all new roofs a few years ago. This is not just for new houses but replacement roof projects.

Tear the shingles off and Do it right and save some headaches in the future.

We did a metal roof on our house about two years ago. 1x4’s over existing shingles. Just about everything else in the neighborhood blew down last week but the roof

Au7mm08

Yeah buts he's an expert on everything. 😉

Exactly what my insurance guy told me just a few days ago

Mackdaddy is a professional roofer

Furring strips and put the screws an inch or more into the rafter if at all possible. It adds structural stability to the whole unit when done correctly. I have no idea how to do that other than poking a bunch of holes in the shingles - not a roofer or a carpenter.

I put down a synthetic underlayment over the shingles. I have used furring strips before but only if the homeowner insists on them. There is really no reason for them. Pm me if you have any questions I’ll be glad to help

I've done several over the years but none in the last 8 years. I removed the shingles and felt completely, put down a fresh layer of decking, new 30# felt then the metal. Screws every 8 inches at the facia and ridge, then rows every 24 running inches. No issues with any so far, but I'm not on the coast either.

Just a layer of felt between the shingles and the tin will be fine. The gravel on the shingles will actually over time rub holes in the tin if this is not done, causing lots of issues

Thanks guys! Mackdaddy I will probly lean on you next couple days keep eye on PM box.

I’ll be glad to help