Can a Metal Roof be Installed Over Old Shingles?

Nice white house with metal roof.

When researching for your roof replacement, one piece of advice given repeatedly is to avoid adding a second layer of shingles. If you consider a metal roof, a contractor may offer what seems like contradictory advice and suggest installing a metal roof over the existing shingles. Does this mean your metal roofing contractor is giving bad advice? In the cases of metal roof replacement, the opposite is usually true, and a metal roof can be installed over old shingles.

How is Installing Metal Over Old Shingles Different from Layering Asphalt?

Layering new asphalt shingles over old asphalt shingles is not recommended in most cases. This will typically void any warranty you may have on your roof. There are several reasons for this. One is that the combined weight of two layers of asphalt shingles is too much weight for the roof. Another is that the bottom layers of asphalt shingles will not allow the sun’s heat to pass into the attic, so the new asphalt shingles will end up staying warmer, which will shorten their life. Metal shingles don’t have these problems. The warranty on the metal roof will not be impacted by installing over asphalt, the weight of metal shingles is one quarter to one eighth the weight of asphalt, which is typically less than the old asphalt shingles will have lost due to wear, and temperature will not damage the metal or finish.

Why Choose to Install Metal Roofing Shingles over the Previous Layer Instead of a New Roof?

Because the typical issues with layering asphalt over asphalt are not a problem with metal, going over the old shingles has several advantages. It allows the homeowner to use their roofing budget for a higher quality metal roof, rather than allocating that part of the budget for removal and disposal. Avoiding a roof removal reduces the chance of damage from unexpected storms during the roof replacement process. From an environmental standpoint, forgoing the removal of asphalt shingles stops them from ending up in a landfill, and can actually increase the energy efficiency of your home during the summer months.

Finding a Quality Metal Roofing Contractor

When choosing a metal roofing contractor, it is important to take their recommendations seriously. If there are signs of water damage and leaks, those will need to be addressed, and that may necessitate removing the old shingles. A quality metal roofing contractor will also take building codes into account, which usually requires that there are no more than two layers of roofing. These roofing contractors will take your home’s situation into account and recommend what is right for your property.

When deciding on materials for your new roof, it’s important to research thoroughly and find a metal roofing contractor you trust to get the right advice. We have the reputation and local experience to install a quality new roof on your home. Contact All-Nu Construction today for an estimate, and for answers to your metal roofing questions.