Metal roofing has taken the residential roofing industry by storm in recent years. However, it causes sticker shock when homeowners get an estimate.
This has led some homeowners to look for ways to get a metal roof without making the full investment. That’s why a new question I’m frequently asked is if installing a metal roof over old shingles is possible.
For over 30 years, the team at Bill Ragan Roofing has provided transparent information for homeowners to use to make the right decision for their situation. Because of this, I’ll help you understand what you need to know about installing metal roofing over shingles.
This article covers the following:
- Can you install a metal roof over shingles?
- 4 things to know before installing a metal roof over shingles
Can you install a metal roof over shingles?
Yes, you can install a metal roof over shingles under the right circumstances. Your current shingles must be near the end of their lifespan and can't be lifted, cracked, blistering, or bumpy.
As long it’s properly installed, installing a metal roof over shingles can be done without a problem. You’ll save up to 25% in labor costs by not tearing off your old asphalt roof, installing new underlayment, or the fees to dump the old roofing materials.
While this sounds great, the truth is that most roofs won’t be a good candidate for installing a new metal roof over the shingles. And even if your shingles are in good condition and a metal roof over is an option, I do not recommend it.
4 things to know before installing a metal roof over shingles
So, installing a metal roof over shingles is an option and will save you money. But as I said, I don’t recommend it.
Now, I’m not saying this as a roofing contractor trying to get you to spend more money. Instead, I want you to be 100% sure you’re making the right decision if it’s actually an option for you.
Below are the 4 things every homeowner needs to know before installing a metal roof over shingles.
1. Your decking is covered up
Decking is the wooden boards that make up the framing of your roof that the materials and components are installed on. Your old roof is torn down to its decking when getting a full roof replacement, which gives your roofer a chance to determine if it can handle your new roof.
If you install a metal roof over shingles, there’s no opportunity to inspect your roof’s decking. If your contractor can’t test your decking’s integrity or inspect for rotten boards, it will lead to costly problems down the road.
This is especially true because you’re adding the weight of a metal roof to an already heavy asphalt roof. The combined weight creates a ticking time bomb for severe structural damage if there’s rotten or compromised decking.
2. You’re covering up a roof that’s at the end of its life
When your asphalt shingle roof has reached the end of its life, all that’s left to do is replace it. Once they’ve reached this point, the shingles have done their job, and the functionality has maxed out.
When installing a metal roof over shingles, you’re just putting a new roof over a failing roof. So, while the metal roof on top looks great, it covers an old roof with problems that haven’t disappeared.
This leaves your home vulnerable to leaks if water gets under the metal panels. And once it happens, you’re looking at extensive and costly repairs if your old shingle roof is bad enough.
3. Future leaks are harder to track and repair
Speaking of leaks, installing a metal roof over shingles makes it much harder to track roof leaks. Once water gets under the metal panels, it runs down and across your old asphalt shingle roof until it finds the path of least resistance into your home.
Because these leaks come from two different parts of two separate roofs, it’s incredibly hard to find the origin. Unfortunately, finding the source is just the first part of the problem.
The roof leak must also be repaired, which gets expensive very quickly because of the skill, time, and labor required to do it right. Even worse, there’s no guarantee the leak will be found and repaired the first time.
4. Crucial roofing materials and components won’t be replaced
Installing a metal roof over shingles means you skip the tear-off process, and, as I said, you’re putting a new roof over a failing one. Not only do you miss out on replacing crucial roofing components, but you also don’t get the right materials specific to metal roofing.
This is especially true for underlayment, a roof system’s last line of defense to keep the decking dry. Not only do you have to rely on the underlayment from the shingle roof, but you also won’t get the right kind of underlayment for a metal roof.
At the end of the day, roofing materials and components aren’t meant to last forever. That’s why it’s better to start from scratch with clear decking if you’re already investing in a metal roof.
Are asphalt shingles or metal roofing right for you?
Now, you know you can install a metal roof over shingles and what you need to know before doing it. As I said, I don’t recommend it.
I understand everyone has a budget, but a new roof is a large investment, no matter what. So, to get the best quality roof possible, you should always start from clear decking and replace all the crucial roofing materials.
With that in mind, you still have a decision to make. But now we’re getting to one of the biggest showdowns in the roofing industry, asphalt vs. metal.
Both types of roofing materials are great options with their own pros and cons. So, you need to know how asphalt shingles and metal roofing compare to each other on key decision-making factors.
Check out Metal Roofing vs. Asphalt Shingles: Which is Right for You so you have the power to make the right decision for your upcoming roof replacement.
