Reroofing is the practice of installing a new roof over an old one, ostensibly to save on tear off and disposal costs as well as save on installation time. While this practice is generally frowned upon by asphalt shingle manufacturers, it may be a different case when you intend to have a metal roof installed.
Reroofing Is Generally Not a Good Idea
Reroofing is entirely dependent on the state of the existing roof. If it happens to have structural issues like water damage, those will still remain and may even get worse. It also doubles the weight of the roof. While this increases the roof’s dead load and making it more resistant to updrafts, the roof structure may suffer from it. Installation doubles the amount of fasteners used on the roof, another factor that may compromise roofing integrity.
Metal Is Different
We at A1 Roofing & Construction do not recommend installing an asphalt shingle roof over another asphalt shingle roof. The risk of premature roof failure is just too great. Metal roofing, on the other hand, is a different matter. A standard standing seam metal roofing system weighs a fraction of an asphalt shingle roof of the same size. The existing roof actually serves as insulation since the outer metal layer doesn’t retain heat.
Work With a Knowledgeable Contractor
Your roofing contractor is key to a successful reroofing project with a metal roof. The existing roof will need to be assessed to make sure it’s structurally sound. The contractors should perform repairs if they find issues that could compromise roofing performance. Most importantly, proper installation techniques, including use of correct fasteners, can go a long way in making sure that your new metal roof will not fail during bad weather.