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Can Metal Roofing Be Installed Over Shingles?

Can Metal Roofing Be Installed Over Shingles?

Metal roofs offer the type of longevity and durability not often found in home building materials. In the humid and moist climate of Northern Florida, they can prove a far better option than traditional shingle roofs. Unfortunately, many people shy away from investing in a metal roof due to higher costs. Part of the high cost of metal roofs stems from installation best practices. After all, tearing off a shingle roof to install a metal roof can incur double the costs. This leads many to ask whether or not a metal roof can simply be installed over top of a shingle roof. We’re here with your answer!

Can Metal Roofing Be Installed Over Shingles?

Let’s say you already have a shingle roof, but you desire a new metal roof for the many benefits they can offer. Will you have to tear off your shingle roof first? No, you do not have to tear off your shingle roof. Metal roofing can be installed over top of shingles.

One of the major advantages of metal roofing is that it is very lightweight. This makes it a perfect material to be installed right on top of an existing shingle roof. Of course, there are some considerations to keep in mind. The first being: local building codes. Before you have a quality roofing company install a metal roof over your shingle roof check with your local building department to ensure it is one of their approved installation methods.

Ensure Your Shingle Roof Is In Good Shape

Almost every building department will comply with this installation process but may have a few caveats in terms of safety.  Generally,  they will check to ensure that the plywood of the existing shingle roof is in good shape and does not contain any soft spots.

This isn’t just to make your life harder. A metal roof is installed with screws that need something to hold onto. Soft or unreliable plywood won’t be able to hold the screws and thus your roof could come off during one of Northern Florida’s famous afternoon thunderstorms. Let’s not even get started on hurricane season.

Keep Building Codes In Mind

In Florida, some municipal building codes state that you cannot have more than two layers of roofing materials on a single residential house. The reason is that when most house trusses were engineered they were designed to only hold so much looking weight.

If one puts too many layers of roofing materials on a home there is a good possibility that the trusses could fall. This is why some counties will require you to remove any existing roofing materials regardless of whether or not it is the only layer of roofing on your home. Only in this way can the building department ensure that the plywood is in good condition and capable of holding another roof.

Of course, this isn’t par the course for most counties and many will allow you to apply a metal roof over the top of a shingle roof.

Installing Metal Roofing Over Shingles

There are two primary methods implemented when installing metal roofing over shingles. The first is running new underlayment over an existing shingle roof, thus covering the old roof. This allows the new underlayment to act as a line of defense in the event that water somehow gets under the metal roof. The second benefit is that it acts as a buffer between the metal roof and the shingle roof. Over time, a metal roof without a buffer can cause the shingle granules to wear away against the back of the metal roofing panels.

The second method involves installing a metal roof over a shingle roof with purlins or battens. In this method, the purlins are screwed down to the roof deck, depending on how the metal roofing manufacturer has designed the panels. The metal is then installed on the purlins. This method gives the installer a nice flat surface to install the metal roofing panels down to without the many grooves and irregularities of the shingles.

Overall, it is up to you the homeowner to decide which installation method is right for you!

The Takeaway

A metal roof can be installed over a shingle roof, but you’ll need to make sure the plywood under your shingle roof is in good enough shape to handle a new metal roof over top. Choosing to install a metal roof this way can save you some dough and garner all of the benefits of a metal roof in the humid climate of Florida!

About Prime Roofing

Prime Roofing is a residential roofing contractor based in Jacksonville, FL. Mark Young, a veteran in the industry, founded Prime Roofing to help homeowners get their roof replaced in a simple, organized, and stress-free manner.

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