Installing a Metal Roof Over Shingles: A Comprehensive Guide

By Amanda Lutz Updated March 21, 2024

Metal roofs have many benefits. They’re long-lasting, weather- and fire-resistant, and both energy-efficient and environmentally friendly, with anywhere from 25% to 95% recycled content. However, metal roofs can be very expensive to install. One way to reduce costs is by installing a metal roof over shingles.

Our comprehensive guide will the benefits and drawbacks of this project, as well as the installation process and pricing.

Overview of Installing Metal Roofs over Shingles

Installing a metal roof over shingles involves a roofing contractor or other professional placing an underlayment over your existing shingle roof and then putting a new metal roof over the top of it. This process saves you the expense of removing your existing roof, effectively providing your home with enhanced curb appeal.

While most roofing materials are too heavy to make a roof overlay possible, metal roofs are unique due to their lightweight nature. They are relatively easy to install over your existing roof, saving you both money and time. Metal roofs won’t add significant weight to your roof, and they’ll offer you greater insulation, reflecting solar heat rather than absorbing it.

Before you decide whether installing a metal roof over shingles is right for your home, you’ll need to check with your local building department. Different cities have different building codes, and some counties and municipalities might require you to remove your existing roof to prevent trusses from falling. Most house trusses are designed to hold a limited amount of roofing weight.

Benefits of Installing a Metal Roof Over Shingles

Metal roofs are a popular option for many homeowners. They work with many architectural styles and can match most homeowners’ preferences. Here are a few benefits of installing a metal roof over existing shingles:

While metal roofing is incredibly safe and durable, it’s still important to have regular inspections. Roofing system inspections by a qualified roofer can detect underlying issues before they present a safety concern. Even as the roofing contractor inspects your roof replacement, they can examine the old shingle roof to make sure there’s no accumulated moisture or damage.

Environmental Impact of Metal Roofs

Metal roofing is one of the most sustainable and environmentally friendly options available. Metal roofs are completely recyclable, and, depending on the material, are made of primarily recycled content. Metal is much more lightweight than materials like asphalt and usually lasts more than 50 years, which is two to three times longer than other materials. Most asphalt roofs require replacement every several decades, even with proper care and regular maintenance.

When you opt for metal roofing materials for your reroof project, you’ll be contributing to a more sustainable environment. Best of all, you won’t have to sacrifice curb appeal since metal roofs are beautiful, functional, and earth-friendly.

Drawbacks of Installing a Metal Roof Over Shingles

Installing metal roofing is a big project to tackle, so it’s important to be aware of potential drawbacks. Here are a few possible issues associated with a new metal roof: 

To safeguard against damage, always hire a trained professional to inspect your roof after a hailstorm or other major weather event. Additionally, ensure proper roof installation by hiring a licensed roofer with underlayment experience and placing a new metal roof over layers of shingles. Your metal roof should last for decades with precautionary measures and appropriate maintenance.

Cost of Installing a Metal Roof Over Shingles

Installing a metal roof over shingles can significantly increase your home’s value, but it can be a very costly investment. A metal roof can cost between $5 and $10 per square foot or even more for premium materials. Placing a metal roof is often less expensive than doing a full tear-off, although there’s still an up-front cost. When making a budget for a metal roof project, factor in the cost of materials, labor, and any required tools.

Your home’s size also plays a role in cost since a larger roof requires more materials than a small one. While most metal roofing materials are more expensive than roofing materials made from wood, asphalt, clay, or composite shingles, remember that their life span is also longer. Depending on how long you plan to stay in your current home, the additional expense could be worth it.

Installation Process for a Metal Roof over Shingles

You can either install a metal roof over shingles yourself or hire a professional roofer to do the job. If you want to install it yourself, here are the steps to follow:

  1. Inspect the shingles: Before setting down a new layer over your old roof, you’ll need to evaluate the existing materials for damage or leaks. You can take this opportunity to check your gutters and trusses as well. Address and repair any areas of concern before installing a new roof.
  2. Install flashing and ridge caps: You can use flashing to seal areas where metal meets another surface, and you can use ridge caps to keep out water and give the roof a finished appearance.
  3. Lay down and secure metal panels: Start by installing metal panels at the roof’s eaves and work your way up, ensuring a panel overlap of at least 6 inches. Once the panels are in place, secure them with roof nails. Make sure to use a waterproof sealant to keep water from seeping into your attic.
  4. Clean up and inspect: After the panels are securely installed, gather any remaining materials and tools and thoroughly inspect the roof. Everything should be aligned, with no uneven edges or gapping.

If you are uncomfortable completing a roofing project on your own, reach out to a contractor. But if you decide to do it yourself, always follow the manufacturer’s instructions for any type of roofing material, and be safe. Use safety gloves and boots with cleats when working on a ladder or roof, or when handling nails and other sharp items.

Maintenance and Care for Metal Roofs

While metal roofing is durable, it still requires regular maintenance, including cleaning and prompt damage repair. Bring in a roofer every year to inspect your roof and make sure there aren’t any problem areas. If there is an issue with your roof, fix it as soon as possible since delaying necessary repairs can cause bigger problems down the road.

Clean your roof, including your gutters and the surrounding areas, using a roof rake or pressure washing tool. You can unveil potential problem areas and keep debris from piling up on your roof by regularly washing it. Routine cleaning and maintenance can prolong the life of your roof and protect your investment.

Life Span of Metal Roofs over Shingles

Most metal roofs can last anywhere from 35 to 70 years. Durability depends on the type of metal you use, but in general, all metal roofs will last longer than traditional shingled roofs. Asphalt shingle roofs usually last between 15 to 30 years.

Shingles come in a variety of different materials, all of which can influence your roof’s durability. For example, clay tiles can easily last around 50 years but are expensive, while fiberglass mixed with asphalt is inexpensive but not very durable.

Our Recommendation

Installing a metal roof over shingles can provide a host of benefits, including improved insulation and durability. While metal roofs over shingles aren’t ideal in every situation—and there might be times when building codes prohibit such a project—they’re a viable option for many homeowners looking to enjoy the positives of a metal roof without the costly labor.

If you want to embark on this roofing project, make sure you understand the benefits and drawbacks and the time it will take to install on your own. When possible, or if you don’t feel comfortable installing a metal roof on your own, bring in a qualified roofer. With professional installation and the right care and maintenance, a metal roof over shingles can provide you with years of security and aesthetic appeal.

Metal Roof over Shingles FAQ

Is it OK to put a metal roof over shingles?

In most cases, it’s OK to put a metal roof over shingles. If you live in an area where building codes prohibit roof overlays, or if there’s existing damage to your decking, you might want to consider a full roof replacement rather than an overlay.

Should you remove shingles before installing a metal roof?

There’s no need to remove shingles before installing a metal roof, in most cases. As long as the metal roofing material is properly installed, putting it over the top of your existing shingles shouldn’t be an issue.

Can you put a metal roof over shingles without furring strips?

We would not recommend putting a metal roof over shingles without furring strips. Furring strips help prevent the buildup of moisture and condensation, aiding in leak prevention and supporting the overall integrity of your roof.

How much more expensive is a metal roof than shingles?

A metal roof can be significantly more expensive than shingles. This is due to a metal roof’s increased life span and enhanced durability over most shingle types.

What is the life span of a metal roof installed over shingles?

With proper installation, most metal roofs have a life span of between 35 to 50 years. In contrast, most asphalt shingle roofs last no longer than two decades. However, this is greatly variable depending on the specific materials used, so consult with a roofing professional for quotes.