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Install Metal Roof Over Asphalt Shingles? (SMART Idea?!)

install metal roof over asphalt shingles

So you want to replace your current asphalt roof with a new metal roof, but you want to know if it’s ok? You’ve certainly heard about the potential when you install metal roof over asphalt shingles after doing some research or speaking with a professional.

Is this, however, a good idea? We’ll break it down for you since we want you to have all of the critical facts concerning such a huge decision.

Once you finish this article, you’ll know whether it’s a smart idea to install a metal roof over an existing asphalt roof, as well as some precautions to take.

Would It Be A Great Idea To Install A Metal Roof Over An Existing Asphalt Roof?

So, can you put a metal roof over your existing asphalt roof? Yes, a new metal roof can be installed over an old shingle roof.

One of the many reasons metal roofs are becoming more popular is that their installation does not necessitate entirely taking off the previous roof, which is a time-consuming and costly job.

Given the correct conditions, you can roof over your existing asphalt roof with a new metal roof. Your current asphalt roof is probably nearing the end of its useful life and is still very level (no lifted or cracked shingles, blisters, or bumps). With that in mind, most roofs will not be excellent options due to the wear and strain they endure during their lifetimes.

It may be done without a problem as long as the new metal roof is properly placed and your local roofing contractor handles everything correctly. 

You can save up to 25% on labor costs by avoiding taking up your old asphalt roof, installing new underlayment, or paying disposal fees for the old roofing materials.

Metal And Asphalt: The Common Residential Roof Types

Metal roof

Metal roofs are classified into two types: standing seam and screw-down panel. A standing seam metal roof system is made up of panels that are joined together at the seams or mechanically seamed. When the metal heats up, this permits the panels to expand and compress freely.

A screw-down panel is exactly what it sounds like: it’s screwed down. Because the screws are screwed through the panel, there is no room for expansion or contraction. Due to its lack of expansion capabilities, I would not recommend installing a screw-down panel over a hot location such as your house or office.

Asphalt roof

Asphalt roofs are classified into three types: 3-tab, dimensional, and luxury. While 3-tab shingles used to dominate the market, dimensional shingles are now the most often installed variety on roofs.

Luxury-style shingles are just as highly marketed as dimensional shingles, but they cost nearly twice as much. Read this article on the three varieties of asphalt shingles to learn more about asphalt shingle roofs.

3 Things You Should Be Wary Of When Installing A Metal Roof Over Your Asphalt Roof

Your decking is hidden beneath your old asphalt roof

Decking refers to the wooden boards that form the roof’s framing. These are the boards on which your roof and other components are installed.

When you receive a new roof, the old one is ripped down to the decking. This allows your contractor to evaluate the decking’s integrity to see if it can withstand the weight of your new roof.

If you install a metal roof over an asphalt roof, you won’t be able to inspect the decking. If your contractor is unable to test the integrity of your decking or examine for rotten boards, it could lead to a pricey problem down the line.

Future roof leaks will be more difficult to detect

When you put a metal roof over your leaky asphalt roof, you are masking the problem rather than addressing it. Water will run down and across your old asphalt shingle roof if it gets beneath your metal panels.

The water will continue to flow until it reaches problem spots and begins to leak into your home. These leaks will be difficult to monitor and locate because they originate in two separate regions of two different roofs.

It’s nearly impossible to discover the source of a leak in your roof when water is streaming across and down your tiles. If you wish to place a metal roof over an asphalt roof, consult with your contractor about the state of your current roof and whether a metal roof-over is a viable option for you.

You will not be able to repair critical roofing materials

When you get a metal roof-over, you avoid the tear-off process that comes with having a new roof. You will save money, but you will miss out on replacing critical materials that are included in a full roof replacement.

Underlayment, for example, is one of these critical elements. It is the last line of defense for your roof system in keeping your decking dry. When you install a metal roof over an asphalt roof, you must rely on the underlayment from the existing roof. You will also not receive the right type of underlayment built exclusively for a metal roof.

Roofing materials aren’t meant to last indefinitely. As a result, if you’re going to invest in a metal roof, beginning from fresh with clean decking is suggested.

install metal roof over asphalt shingles


You now understand how to put a metal roof over an asphalt roof. You also learned three precautions to take before obtaining a metal roof replacement.

Remember, while it is possible, I would not advocate it. I appreciate that everyone has a budget, but if you’re going to invest in a metal roof, you should remove your old asphalt roof first. To acquire the greatest quality roof possible, start with clean decking and replace all critical roofing elements.

Metal, while extremely strong, is extremely light, weighing less than a pound per square foot compared to up to four pounds per square foot for asphalt shingles. The addition of a metal roof over existing shingles does not considerably increase the overall load on the housing structure.

Installing a new metal roof over an existing roof not only saves the cost of entirely removing the present roof but also provides the benefit of more insulation above your home to keep heat and cool from escaping.