5 rib exposed fastener metal roof over existing roof DIY


I have a 35 year old house with 24 inch eves and 4-12 pitch & asphalt shingles
I am located in dry dry AZ so I am not concerned with mold,condensation & ect
I want to put a metal roof on my house (see subject line)
I know a guy who screwed his roof down on top of the existing asphalt shingles
To me this seems like a bad idea B/C the screws might not squish the neoprene washers properly
I have seen vids of guys nailing down furring strips so the screws will have a good surface to seal against
This seems better but the metal roof would not be completely supported
I am wondering about putting down a complete layer of OSB instead of furring strips


Put down your metal directly on top of the shingles (well at least put a layer of underlayment over the shingles first) or put down furring strips and metal on top of them. But I would NOT recommend putting a layer of osb or sheeting over your shingles! With that idea you are making it just as much work and cost of tearing your old roof (best option) for a subpar alternative. I’ve screwed down metal over existing shingles many times before, never had an issue with the washers.


You just need to make sure your existing roof sheeting is in good enough shape (no rot) that all your screws have something to bite into. If its not than my recommendation is for you to install horizontal furring strips (16" on center).


OK thanks!
It is allways good for a DIY like me to talk with experts
What would be good for furring strips?


1x4, 1x3
I dont like the usual ones with the hard edges.
Look around until you find the ones with softer, rounded off edges.


Yeah I recommend anything 3/4 to 1" thick. Anything thicker and sometimes it can be difficult to find wide enough trim pieces.


Choose your manufacturing company for your metal. Follow the instructions from manufacturer to the letter.:+1::+1:


Remember if using furring strips…they need to be treated or strip covered with peel n stick. Metal condensate so spruce or fir will rot rapidly. Make sure to SCREW lathes to rafters.