Options in a Roof Replacement When You Want to Switch From Shingles to Metal Roofing

If your shingle roof is old, you might want to replace it with a metal one instead of getting new shingles that wear out faster. When you get a new metal roof, you might have it installed over your old shingles or the contractor might tear off all your old roofing and put on completely new materials. Here's a look at these two approaches to a roof replacement when you want to switch to metal roofing.

Covering the Asphalt Shingles

First, find out if adding metal roofing to your old roof is permitted by local codes. Your roofer knows the codes, but you might want to call the codes office before you talk to the roofer. One requirement will probably be that your current roof is still in fairly good condition, even though it's old.

A metal roof can be installed over asphalt shingles because metal is lightweight. The roofer may put down a framework of boards first that are nailed to the rafters and then nail the metal roofing to the boards rather than your old roof. This ensures the metal roof is attached as securely as possible and can withstand storms with strong winds.

In some cases, underlayment may be put over the old shingles to add another barrier against rain. If you choose to cover the shingles when you get a roof replacement, the roofer will install the new roof so the old shingles are protected and at low risk of damage and moisture problems.

Tearing Off the Old Shingles

Your roofing contractor may not recommend covering your old shingles. For example, if you cover the shingles and the deck has soft areas that are not discovered, they get covered over. This could cause your roof to wear out quicker and shorten the usual long lifespan of a metal roof.

Another problem that might develop is that a leak could be much more difficult to pin down and repair. Although it is quicker and less expensive to cover your old roof, a complete, new roof replacement has its advantages. Your roofer removes all old roofing to ensure the deck and everything placed on it are strong and ready to last for decades.

A metal roof is usually more expensive than asphalt shingles, so if you're paying for the increased durability and longer life that metal provides, you might want to start with all new roofing materials. However, you can discuss your options with your roofer and figure out the right approach for your home, given the condition of your old shingles.