How Tar and Gravel Roofs Stack Up Against Other Options

Referred to as “built-up roofs” (or BURs), tar and gravel roofs are a popular option for people who own a commercial space. But, just because they’re common on commercial spaces doesn’t mean you can’t have a tar and gravel roof installed on your home.

If you have a flat roof house and need a replacement, it’s time to learn about tar and gravel roofs, their benefits, costs, and more.

Types of Tar and Gravel Roofs

Tar and Gravel Roofs

There are two types of tar and gravel roofs: modified bitumen roofs and ballast roofs. Even though both types fall under the same category, they contain different materials, and the process of installing them is different. Before setting on tar and gravel, you’ll need to decide which type is right for your roof.

Modified Bitumen Roofs

Modified bitumen roofs are the result of adding modifiers to typical roofing asphalt. Once those modifiers are in place, fiberglass or polyester fiber matting reinforces the mixture, resulting in a more robust, longer-lasting roof. Depending on where you live, you’ll need to choose between SBS and APP-modified bitumen roofs. The primary difference between these two types is the roof membrane.

Modified bitumen roofs provide excellent traction, making repairs easier. The space between the gravel helps to promote evaporation and release heat, which helps protect the layers under the roof’s finish.

Ballast Roofs

The biggest difference between ballast roofs and modified bitumen roofs is the size of the gravel. If you live in an area with an ample supply of ballast (rocks and gravel of the right size), ballast roofs are more pleasing to the eye.

Ballast roofs are much easier to repair since the larger gravel isn’t embedded into the membrane. If there is a tear in the membrane, contractors remove the large gravel, repair the membrane, and put the stone back into place.

Ballast roofs provide Class-A fire resistance without needing expensive gypsum underlayment. This level of fire resistance can provide a benefit to your insurance policy. The makeup of ballast roofs makes them one of the most energy-efficient options in the industry.

Cost of Tar and Gravel Roofing

There are several factors to consider when determining how much a tar and gravel roof will cost. It’s important to remember that while you can only install a tar and gravel roof on a flat roof, flat roofs still have pitch. The size of your roof, the degree of the pitch, and local market factors will impact how much it costs to have a tar and gravel roof installed on your home or commercial property.

Based on national averages, it costs between $3,750 and $6,750 to have a tar and gravel roof installed on your home or building. Roofing contractors provide estimates based primarily on the square footage of the job.

In roofing, one square is equal to 100 square feet. Tar and gravel roofs cost between $250 and $400 per square, meaning they cost between $2.50 and $4.00 per square foot. The low price per square makes tar and gravel roofing very affordable.

How Much Does Tar and Gravel Roof Repair Cost?

No matter how often you have maintenance performed on your tar and gravel roof, there will come a time when you need to have the roof repaired. Tar and gravel roofs are affordable to repair. When a tar and gravel roof requires repair, the contractor will cut the damaged portion of the roof out and replace it with a new piece, creating a patch.

However, industry experts say that if 25% of your tar and gravel roof has patches, you should plan on having a new roof installed sooner than later.

The same square-footage prices for tar and gravel roof installation apply to repairs. That means that if your tar and gravel roof has a damaged area of only 3 square feet, you can expect to spend between $7.50 and $12.00 for the material. There will be labor costs to consider, but the low cost of materials will help you save on your repairs.

Frequently Asked Questions (FAQ)FAQ

How long do tar and gravel roofs last?

Tar and gravel roofs last between 20 and 30 years on average. This number can vary depending on the climate in which you are having the roof installed.

Are tar and gravel roofs easy to maintain?

Maintenance on a tar and gravel roof includes adding additional layers as needed. While this process isn’t “easy,” the materials are often more affordable than other types of roofing, making it more affordable. It’s also worth noting that this process won’t need to happen every year, unlike maintenance on some other roof types.

What is the most common repair on a tar and gravel roof?

The most common repair on a tar and gravel roof is a tear in the membrane, which allows water to leak into the building. You can easily repair these with a patch.


Tar and gravel roofs are some of the most popular roofing systems in the United States. They’re affordable, easy to maintain, and can last up to 30 years. Additionally, tar and gravel roofs provide Class-A fire resistance without expensive gypsum underlayment.

If you’re considering a new roof for your home or business, a tar and gravel roof should be at the top of your list.