Is A Tar & Gravel Roof Right For Your Commercial Property?

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Is A Tar & Gravel Roof Right For Your Commercial Property?

Is A Tar & Gravel Roof Right For Your Commercial Property?

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Tar and gravel as a roofing material have been around for over a hundred years.

Among its many benefits, it’s a popular roofing option mainly for its affordability, durability, and ease in installation. It can be used for other forms of construction too.

Whatever your reason may be for looking into tar and gravel roofing, we hope this article will be of great help.

What is a Tar and Gravel Roof?

Tar and gravel roofs are also known as “built-up roofs” or BURs.

The process of tarring a roof involves adding alternating layers of hot tar, roofing felt, and gravel.

Other roofing materials of mineral aggregates and fiberglass are often explored for built-up roofs. Waterproof materials are also placed to maintain the dignity of your tar roof.

You can choose the number of plies once you have them installed.

This will highly depend on the type and weight of your chosen roofing materials, your building’s structure, and the weather of your location. Make sure to get the expert advice from roof professionals on this matter.

Gravel roofing is usually the choice of roof finish because of its “flood coat”. Pea gravel minimizes sun damage and protects the roof from heavy rains. Others also prefer other roof alternatives like crushed ballast stones.

Built-up roofing is the more economical choice for a flat roof.

Although, you will often only find tar for roofing in commercial buildings rather than residential homes. Not that it is not a viable option, but it is important to note that tar roofs can be troublesome when it comes to water leakage.

We will look more into the pros and cons of a tar and gravel roof later on in this article.

Advantages of a Tar and Gravel Roof

Before considering built-up roofing for your home or commercial building, check out these advantages to boost up your confidence in your decision.

Water and Weatherproof

Tar and gravel have great protective qualities from harsh climates like heavy rain, wind, snow, and hale.

The amount of layers, quality, and thickness of your built-up roof plays a big factor in this too. With proper maintenance, you’d expect it to last for decades.


Tar and gravel roofing systems have a life expectancy of 20 to 30 years. It’s not as long as your metal roof options, but you get the value of what you pay for.

After those years, you’ll most likely see degradation and perhaps experience some bad performance. However, for as long as you get them immediately repaired when deterioration starts to show, you’ll definitely be adding more years to your roof’s life.

Tar and gravel are very resistant to extreme sun exposure. It is also a fire retardant.

The final gravel coating effectively reflects sunlight and protects your roof from harmful UV rays. This keeps your house well insulated especially during hot summer days.

Apart from that, tar and gravel roof surfaces are also very tough, which gives it added strength.

Layers of bitumen and rocks keep the surface from wearing and tearing easily. Even if you walk on them, or have some leaves and unwanted debris, it won’t cause you potential problems.


From the roofing material itself, installation costs, down to maintenance, repairs, and replacement costs, a tar and gravel roof is your most cost-effective option.

Material costs will greatly differ depending on the number of sheets and layers you want to be installed on your flat roofs.

Since overall, this type of roof is not so much of a pain for your pockets, we encourage homeowners to might as well hire experts to install them.

Ease in Installation

It won’t take long for a roofing contractor to install your built-up flat roofs.

In spite of its ease in installation, we don’t recommend having this as a DIY project. Pouring hot asphalt, and roof gravel materials is a tedious job with many risks. Under the wrong conditions, hot tar can burst into flames.

Energy Efficiency

As earlier mentioned, the features of these BUR roofing materials allow you to regulate the temperature of your home.

This means you don’t need to spend extra on energy costs caused by necessary air conditioning during the summer. You are sure to end up with lowered electricity bills.


Tar and gravel roofs are aesthetically pleasing. They give a minimalistic style and clean touch to any roof.

Disadvantages of a Tar and Gravel Roof

I guess you can say nothing is perfect. Here are some of the disadvantages that come with tar and gravel roofs. If these don’t bother you as much given all its wonderful benefits too, then why not still give it a shot.

Added Weight to Structure

A tar and gravel roofing system can substantially add to the weight of your roof structure.

After adding layer over layer of tar, supporting fabrics, and gravel, you could add around 5 to 10 pounds per square.

If the condition of your overall structure is not that great or has a weak resistance to harsh elements of nature, then maybe you should give it a second thought.

Difficult to Perform Maintenance

In case of damage or leakage, it’s easy to tell where the problem is coming from. However, removing the entire region of the roof’s problem will take quite some time and money as compared to membranes or polyurethane foam roofs.

Gravel can also clog gutters and scuppers.

A roof contractor may remove the thick layer of gravel with the use of a vacuum or by way of shoveling it off.

Breaking down of Gravel Stones

With the test of time, weather, and foot traffic, the gravel stones on a commercial roof may start to break down.

If they do so, they become less effective and become more prone to cracking and leaking. Adding an extra layer for repair and maintenance should be done at this point.

Foot Traffic Damage

Most commercial roofs can be walked on. Foot traffic may be caused by a maintenance team who needs to clean the windows and decks.

If there are sharp pieces and persistent forces that push into the underlying layers of protection, this will make the roof vulnerable over the course of time.

To increase the lifespan of your roof, best to create a specific walking area or path on your gravel roof.

Prone to Mold

A flat roofing system is always prone to standing water. When installing a single ply, contractors should be mindful of a drainage system.

Water can be trapped with every layer of gravel. Evaporation is a slow process that leads the way for moisture and mold growth.

Not Earth-friendly

The materials for this type of roof are not recyclable. Once it no longer serves its purpose, the asphalt and stone go directly to the pile of dump. It is non-biodegradable too.

As much as possible, we would want to have eco-friendly roof options.

How to Maintain Built-Up Roofing

Ideally, you would want your roofing structures and underlayments to be inspected every year.

In any case you encounter damages, don’t wait too long to have them fixed.

Regularly cleaning your roofing system including the drainage slope, especially after strong winds is a good maintenance habit.

Make sure to hire service from trusted professionals to avoid further concerns.

How Long Does a Tar and Gravel Roof Last?

So far, based on the experiences of roof system experts, BUR roofing systems can last for as long as 30 years.

Yes, it is resistant to UV rays, extreme weather, and foot traffic. Over time though, discoloration, loose areas, and cracking will soon show. Patching it up with added layers of weatherproofing will help.


There’s quite a number of options for roofing materials. A tar and gravel roof would be best if you are working on flat roofing, preferably commercial, and on a tight budget.

The big advantage of this roofing system is surely its durability. However, it is still far from perfect.

We encourage you to weigh in all the advantages and disadvantages we’ve provided for the choice of a tar and gravel roof, in this article. For any questions, feel free to leave us a message.

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