Can you put metal roof on shingled roof (3 layers) or does it need to be torn off?

Answer 1

Best Answer - Chosen by Asker

Remove the shingles, in many states the building code stipulates no more than 2 layers.

But the attachment of the metal panels will be much more secure if the screws used can go directly into the wood below. Also if you leave even one layer below, the shingles being in contact with the back of the metal panels may void the warranty of the roof.

The best way to attach the roof is to strap the roof with wood or metal strapping every 48" running the length of the roof. This strapping should be screwed directly to the joists if possible. Then your metal roof would be secured to the strapping. Depending on your climate you may want to add rigid insulation board between the strapping, possibly use 2 x 4 as strapping to allow 1-1/2" of rigid insulation which is the equal of 3" blanket.

Source(s):

35 years construction experience, most using metal building materials.

Asker's Rating:

Asker's Comment:

Thanks, just validating what should be done. Owner didn't want to go to expense of tearoff, but this validates it. Good idea on adding purlins and rigid insulation.

Answer 2

you have way too many layers of shingles already. insurance companies will tell you it;s ok to have 2 layers on (because they don't want to pay to have them taken off and hauled away) you do not have to agree to that.

Answer 3

The metal roofing has to be secured with bolt type things which means you want it really tight to the surface, so yes the shingles have to go.

Answer 4

There should not be 3 layers of shingles, to start with. 2 is maximum allowable.

Answer 5

Yep, take off shingles.!!