Can You Install a Metal Roof Over Asphalt Shingles


When your current shingle roof becomes less efficient, you may want to upgrade with better material. Most homeowners will go for metal roofs because it’s more durable and energy efficient. However, the way you do it matters a lot.

Should you install metal roofing over your old asphalt shingle roof? This is a question that brings out different views from different people.

Having metal roofing panels over asphalt shingles seems cost-effective, but it might not be the best idea. Not only is an asphalt shingle roof different from a metal one in terms of material and quality, but metal roofing installation is also different.

For instance, installing metal roofing materials requires a more qualified contractor. This is because metal roofs seem more complex than asphalt ones, which you can simply DIY.

So, you may have heard about the possibility of double roofing. But is it worth it? We will answer this question in this with more information from our roofing experts.

About Metal and Asphalt Shingle Roofs

Knowing as much information about roofing materials before using them is important. You can check with your local building department if you are not sure where to start. Here, we introduce you to metal and asphalt roofing materials. This will help you determine whether installing one over the other is worth the trouble.


Asphalt Roofs

Asphalt roofing systems are extremely popular. It is a common material that you will see in most homes. These roofs come in three types; 3-tab, dimensional, and luxury, with 3-tab as the dominant option.

When installing a metal roof over shingles, it matters a lot which specific type is on your existing roof. It’s much harder to install a metal roof over luxury shingles, for instance, as they are relatively heavier and more expensive.


Metal Roofs

Just like asphalt shingles, you may have come across a steel roof in your area because metal is another common material. They are usually made from steel, aluminum, zinc, or copper. You will either have a standing seam or screw-down panel on your home.

Standing seam metal roof systems come as a series of panels locked together at the seams or seamed mechanically. The seams can expand or contract easily. The screw-down roofs are screwed on the frame through the panels, which leaves no room for expansion.

Installing metal depends on the specific roofing material you choose. Some are more challenging and costlier per square foot, while others are easier and more affordable. You need to put this into consideration when looking for a roof replacement, especially where double roofing is concerned.


Can You Install A Metal Roof Over Asphalt Shingles Existing Shingle Roof?

A new roof is necessary when your old roof becomes less efficient, and your existing shingles start falling off. Installing metal roofing over an existing asphalt roof is an option, but it’s not good. Your roofing contractor may advise you to just tear the old roof off and get a new one in place – follow that lead.

As you can see, there are clear differences between metal and shingle roofs. Still, some people will want to install one over the other. Some of the reasons for this include:

  • To reduce labor costs. Installing a brand new roof requires the old roof to be removed, something not every homeowner wants. It costs more than just patching other material over the current roof.
  • It seems easier. You may not know what material is on the previous roof when another one is installed on top. It seems like the easier solution, especially when you lack time.

But should you do it? Experts recommend against double roofing. Some states even have laws and regulations against it.

Reasons Why You Should Not Install Metal Over Your Asphalt Shingles Roofing System

And here are some reasons why having a double roof over your house is not a good idea.

The Old Roof Covers the Decking

Depending on your installation method, the roof may have a specific type of decking. These wooden boards create the roof’s framing to hold the roofing material.

A complete tear-off is required for a proper re-roofing process. The old roof is torn down, leaving the decking. The contractor then inspects its integrity and determines whether it can handle the new roofing materials.

With two layers on the roof, there is no way the roofer will check this decking. And if its integrity cannot be ascertained, there is no way of knowing how long the roof will last.

You may want to save money by installing two or three layers on your roof, but the long-term costs may not be worth the risk. You may end up paying a lot more in damages than you would have with a full replacement job.

It Might be Hard to Work on Future Leaks

Leaks and high energy costs become constant issues when an asphalt roof gets old. Installing metal materials over these old shingles just covers the problems without fixing them. What happens when water gets under the metal panels? It will keep running across the old roof with no chance of fixing.

You can install a metal roof on the shingles to improve curb appeal, but that will not matter when water leaks inside your home. It will be very hard to track and find a solution because the leaks come from two different roofs. And that is why it’s not worth it to install metal over an asphalt roof.

Makes the Roof Too Heavy

The roof decking is often designed to handle a specific weight. Every roofing material comes with a standardized decking. That is why every new installation requires new underlayment to meet those demands.

So, the additional weight that comes with installing a metal roof over an asphalt one may make it less efficient. Your roof can even collapse, forcing you to spend more on damages. You can avoid that by following the recommended methods.

You Can’t Replace Important Roof Materials

With one layer on your roof, a complete tear-off is necessary for the new roof to be installed properly. Installing a metal roof over it means bypassing this process and missing out on replacing some crucial materials, like the underlayment. Remember, these materials are not meant to last forever.

It Might not be the Most Eco-friendly Solution

Metal is one of the most environmentally friendly materials on the market. Asphalt shingles offer the same benefits. But this is only possible when the roofs are one layer. Heat build-up in your house is inevitable when too many layers are installed.

Ask your local roofing contractor, and they will tell you that is not the best way to go. Installing a new material directly on the underlayment allows the contractors to check other features that make a house more eco-friendly.


Installing a metal roof over an asphalt shingle roof seems like the best way to save on the cost of replacing a new roof. However, it is only a cheap option for homeowners who don’t want a good roof and a lasting solution. And that is why expert roofers will never let you follow such a path. The risks are more than the rewards; the law may not even allow it in some states.

Do you need a new metal roof to update your current asphalt roof? Equity Roofing is here to help you. Our roofing experts will come to assess your current roof before offering the best solutions. We are the most experienced roofers in the region, with many years of experience and an eye for quality materials.


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