adding a metal roof over ...: "I'm putting Master-rib metal roofing over an existing asphalt shingle ..." - Guest User (5/28/2004) | Roofing over existing roof | Archive

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I'm putting Master-rib metal roofing over an existing asphalt shingle roof. What should the screw spacing be on both the edges and in the field.	Guest User 5/28/2004	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/2738/find/
30-pound felt is considered a moisture barrier rather than a vapor barrier. Vapor barriers, when installed, are usually behind the drywall in walls and ceilings for the purpose of keeping moisture from migrating into walls and attics. Felt, a moisture barrier, acts to protect the substrate beneath a roof from condensation. It can also help guard against roof leaks to some degree. In your case, the old shingles are in place to protect the decking. I personally am not fond of installing over asphalt shingles without an underlayment in between because expansion and contraction of the metal can cause abrasion to the metal as it rubs against the rough granular surface. In your case, though, your roof system is not designed to have a lot of movement so it is less of an issue. Just the same, my recommendation is to always have underlayment between the metal roofing and old shingles. I would look into what the installation procedures put out by the metal roofing manufacturer call for.	Todd Miller Isaiah Industries, Inc. 5/29/2004	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/2739/find/
Screw spacing is based upon numerous things including the roofing profile and the metal thickness. This information must come from the manufacturer of your roofing material and will be based upon load tables which have been established through physical testing and engineering studies done on the roofing.	Todd Miller Isaiah Industries, Inc. 5/29/2004	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/2740/find/
What should the spacing between the 1X4s be?	Guest User 5/29/2004	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/2741/find/
All information concerning fastening, spacing, etc. must come from the roofing manufacturer. These specifications vary from product to product based upon physical testing and engineering studies.	Guest User 5/29/2004	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/2742/find/

adding a metal roof over existing asphalt