Is it Possible to Install a Metal Roof Over Shingles?Published on Monday June 1, 2020
Metal roofing is a more efficient and longer-lasting roofing alternative to asphalt shingles. While asphalt shingles are the traditional option, metal roofing is becoming more and more popular in the residential space.
If you already have a shingle roof and are looking to make the switch to metal roofing, you may be wondering how that process works. Do you need a complete roof replacement? Or can you install a metal roof over shingles?
You can generally install a metal roof on top of shingles as long as there are fewer than four layers of shingles on the roof, but the exact standards vary by area. However, that process can lead to a variety of complications and therefore is not recommended.
Why Not Install a Metal Roof Over Shingles?
While installing a metal roof on top of shingles seems like it makes the job easier, metal roofs are a challenging project. If you don’t have experience in roofing, or skills with metal roof installation specifically, you should always call in a professional roofer with metal roofing experience to ensure the job is well done and damage is avoided.
When bringing in a roofing professional to install a metal roof over shingles, this is the process they typically follow:
First, the roofer creates a slat board base to support the metal roof on top of the shingles. This is created by laying lengthwise furring boards every two feet along the roof, and then attaching them to the roof with 3-inch wood screws from the bottom of your roof up.
Next, they install metal edging around the perimeter of your roof as well as metal sheets to the framing. Metal sheets need to be installed one at a time with screws spaced two feet apart. Each following sheet overlaps the sheet before it.
Once the roof is covered in metals sheets and attached with screws, the roofer will install metal trim along the roof’s edge and top ridge. They should then use notching scissors to put a notch in the metal in the middle so it bends over the ridge.
Lastly, the roofer will install closures or a self-adhesive to seal any openings and prevent moisture, debris and pests from getting under your metal roofing.
This may seem like a fool-proof method.
But there are a variety of problems that can arise when installing a metal roof on top of shingles: It’s more difficult to inspect, it could create an uneven surface, and it can ultimately shorten its lifespan.
Here are the details on some of the most important reasons why the existing shingle roof should be removed prior to the installation of a new metal roof:
1. The only way to inspect the roof decking and ensure there’s a solid foundation for the new roof is by removing the existing shingles and stripping the roof down to the wood. This gives the roofing professional a more accurate view of what’s going on beneath the hood. If there are any signs of damage, like wood root, the entire roofing system needs to be rebuilt.
2. When installing the furring boards over shingles, you risk creating an uneven surface for the metal roofing that can make the final product appear wavy or deformed. This creates both functional and aesthetic issues for the new roof.
3. Some roofers will install metal roofing directly to shingles without laying a wooden base to build upon. When metal roofing is attached directly to shingles, the asphalt granules can wear holes into the coating of the metal roofing and shorten its lifespan.
Making the switch to metal roofing is a big investment, so you shouldn’t cut corners that will ultimately diminish the value of the new roofing system. When installing a metal roof, it really is best to remove the existing shingle roofing first to avoid any undesirable results.
Benefits of Having a Metal Roof
As you browse the material options available for your roof, you should consider the benefits of metal roofing — it could be one of the best investments you make for your home:
When compared to traditional shingles and other roofing materials, metal roofs do a much better job of keeping your home cool during the summer months. Reflective coatings and thermal breaks can reduce cooling costs by up to 20 percent. This improves your home’s energy efficiency since your AC unit won’t need to run as hard to cool the interior air.
Fire and Wind Resistant
Unlike traditional asphalt shingles, metal roofing is resistant to fire damage caused by electric storms and lightning. Additionally, since most metal roofs panels interlock or overlap in some way, they are far more wind resistant than other roofing materials.
50+ Year Life Expectancy
While other roofing materials like asphalt shingles can diminish in value and quality as they age, are exposed to wind and rain, and undergo snow and ice exposure, metal roofs provide long-lasting benefits as they are more resistant to weather elements. Most metal roofing has a life expectancy of 50+ years.
Metal roofs come in a wide variety of designs, making them highly adaptable. There are different metal roofing materials available for different types of roofs, including products that mimic the appearance of wood, slate, tile and even shingles. No matter the style of your home or the complexity of your roof, there are metal materials to suit your needs and preferences.
The older your home gets, the more damage a weighty roof can cause. Lightweight roofing materials like metal roofing help protect your home from structural movements and the damage caused from that, especially in areas susceptible to earthquakes. Metal roofs are one of the lowest weight roofing options available for residential homes.
Cost to Install a Metal Roof
Metal roof installation is a labor intensive task, requiring a competent, skilled roofer with a great deal of experience to manage this type of installation project. When you’re using a more expensive material, the cost to install a metal roof can be on the higher end of the scale. However, the benefits that come with a metal roof are worth the investment.
Ready to Upgrade Your Roofing?
Interested in making the switch to metal roofing? Trust Long Roofing for the job. With a Class 4 distinction in impact resistance and a Class A fire rating, our metal roofing is made to withstand a variety of damaging forces. More durable than wood, slate and asphalt, as well as algae, rust and mold resistant, your metal roof from Long Roofing is sure to last a lifetime.
Contact the Long team online today to get a quote, schedule a free, in-home consultation or find answers to any of your roofing questions.
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