How To Install Metal Roofing Over Old Shingles. This is because by installing the new roof over the old one, you can easily miss any damages, water spots, mold, or rot that may be underneath the old singles or. The low weight of metal roofing is one thing that encourages this.
A benefit to doing it this way is that you can see if there is any rotten plywood that needs to be replaced before installing the new roof. Metal roofs also offer greater insulation during the colder months, especially when you install them over top of your old shingles. The industry standard for underlayment is often thought of as felt paper (tar paper) but there are also many newer synthetic underlayments that are designed to work well with metal roofing.
The first is to apply an approved underlayment over the old shingles.
The first one being that the new. Pros and cons for metal roofing installation A benefit to doing it this way is that you can see if there is any rotten plywood that needs to be replaced before installing the new roof. The metal roof must rely on the building’s framework for full support.