How To Install Metal Roofing Over Old Shingles. The second way is to install 1×4 purlins over the shingles. If you are ready to give this a go, talk to us and let us help you out with your metal roofing needs.
Find out how to replace an old roof with a metal roof. Herein, can you put a metal roof over asbestos shingles? Do you have to remove shingles before installing a metal roof?
Although it is fine that you know how to install metal roofing over asphalt shingles, metal roofing always requires more specialized skill sets, making a job best reserved for professionals.
The purlins are screwed into the roof deck, and that depends on how the metal roofing brand has designed the panels to. A layer of underlayment installed on top of the existing shingles will help keep the granules of the old shingles from rubbing against the back of the metal and causing possible corrosion. Though there are many ways to install a metal roof over shingles, we recommend this installation method, which provides the most durability over time. It will also give you a nice, flat surface to install your panels on.