steel roofing over shingles 3 miles from ocean

Guest User
I have put on 11 steel roofs in Wisconsin over shingles--some had been on 10 years and still look good--the original company that I bought the steel from recommednded that I screw them down only on the high spot and they will look much more even--they were correct--the first one I put on was over shingles and I screwed it down on both the high and low spots and it looks ok but the next one I put the screws on the high spot only and it looks much better---My question to you is the roof I am looking to put on now is 3 miles from the ocean in biloxi,ms--I'm sure the salt water will have an effect on the durablity of the product but I see after the hurricane that the steel roofs with the 1x4 boards under them blew off much more then the ones that were screwed right down to the singles--they are only as strong as the 1x4 is connected to the roof and also the wind can get under the steel more if it is raised up. what is your take on the salt and the 1x4 boards--Jim
Allan Reid
Dura-Loc Roofing Systems, Inc.
Choose a system that has been tested to UL 580 and 1897 wind uplift tests. It will indicate gage, attachment, screw size and placement, etc. If it does not have this test do not use it. Certainly nailing 1 x4 to the existing deck will not pass this test. I would remove the existing shingles and renail the decking to the Florida building code standards and also look at the overhang framing. I recommend screwing the decking. Know what you are fastening into. Salt will not effect the lumber but it will effect the fasteners. Make sure they are long life coated and resistant to the pressure treated lumber you need for termite protection. As to metal roofing, at 3 mile inland the salt air is not as bad but the humidity is in your area. Make sure the roof is ventilated and use a G90 painted in a PVDF or CSMP paint system, or use a Galvalume AZ55 or granular coated product, or painted aluminum product that stand up long term.
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