Flat roofs last anywhere from 10 to 50 years. Why is this lifespan range so long? It has to do with the wide variety of roofing materials available for each flat roof.

Each of these sits somewhere on a scale from least to most durable. Roof materials on the latter mentioned side last longer than those on the former. Knowing where each one lies can help you choose the longest-lasting flat roof type for your business.

Read on to learn more about these and their levels of durability.

What Is a Flat Roof?

Children will often draw buildings in which a square represents the main floors and a triangle represents the roof. The latter shape does not accurately portray a flat roof. Rather, it more closely resembles a simplistic version of a sloped roof.

To depict a building with a flat roof, the child wouldn’t include the triangle. They would instead simply draw a horizontal line at the top of the square as per usual. More detailed drawings may include railings or furniture, but this isn’t necessary.

However, one thing to keep in mind is that flat roof surfaces are not exactly the same as most floors. Instead of building one side level with the other, roofers will set one side higher than the other. Roofers do this to facilitate drainage and keep the water from pooling.

How Is a Flat Roof Built?

When standing on a flat roof or looking at one from above, you’ll notice that roofers have placed gravel, bitumen, or another material over its surface. However, there is a lot more that remains unseen.

When flat roof installers first create a roof, they build the foundation first. This usually consists of joints and a deck. Once they finish this, they place multiple materials over this construction in layers.

Each material that a roofer uses has a specific purpose. Typically, each roofing type will have weatherproofing, reinforcement, and surfacing layers.

The exact materials the roofers use for these purposes vary. Each one has its own levels of strength. However, except with custom jobs, a flat roof company most often installs specific groups of materials together with different surface layer types.

For this reason, this article won’t go into the specifics of the durableness of each material involved in flat roof construction. Rather, it will describe the average strength of each group of materials. It will also, as roofing contractors do, label these groups by their top layers.

Tar and Gravel (BUR) Roofs

A tar and gravel roof, often also known as a conventional built-up roof, has a top layer of gravel and a layer of tar directly below it. This is a very popular roofing type as it’s cheap and low-maintenance. When properly maintained, it lasts around 15-30 years.

However, there are a lot of things that can go wrong during that lifespan. Experts say that this roofing type doesn’t hold up well in extreme weather conditions. Also, once it springs a leak, flat roof contractors can spend a lot of time looking for the location of the damage.

Still, once contractors find the damages, it’s usually easy and cheap to fix.

Bitumen Roofs

Bitumen is a roofing material consisting primarily of asphalt. One of its downsides is its complicated installation process.

On top of placing all the under-layers, flat roof installers also have to perform several steps on the top bitumen layer. These can include melting the seams of bitumen sheets together and adhering them to the layer below.

However, enduring this process is worth it. A bitumen roof lasts 20 years or more. They also fare well against most weather conditions and roofing contractors can repair them easily.

Membrane Roofs

Membranes are different coverings that roofers can place on the top layer of a flat roof. All the roofing materials in this category are waterproof. As a result, they often do an excellent job of keeping moisture out of a building.

There are a few different varieties of this roof type and each has its own pros and cons. For example, rubber or EPDM membranes last from 25 to 30 years. They also have the advantages of a cheaper cost and a quick installation process.

Thermoplastic membrane roofs (TMR) fare well in higher temperatures. They are also a cheap option and very energy efficient. They have a lifespan of around 15-20 years.

Spray-On Polyurethane Foam Roofs (SPF)

The roofing installation process of this material involves spraying it onto the top layer of a flat roof. Flat roof installers will then wait for it to expand into foam. While it does so, it will fill the full flat roof surface, including every crack, and adhere to it.

After this, an installer will spray on a waterproof topcoat. This leaves the flat roof invulnerable to moisture. While this roofing type is expensive, it’s well worth the excellent protection it provides.

It also has a long lifespan of 40 years or more.

Metal Roofs

Metal is one of the strongest roofing materials. Its average lifespan is around 35 years. However, a flat roof of this type will often only last this long in climates that are warm and dry.

In addition, the final lifespan can vary based on the exact type of metal that you choose for your project. For example, steel is stronger than metals such as aluminum.

Concrete Roofs

Concrete is another incredibly strong roofing material. Flat roofs made with it can last around 50 years. It is also easy to maintain and endures most weather conditions well.

However, keep in mind that concrete is a porous material. This means that water can seep through it and then make its way into the building below.

Let Us Lengthen Your Flat Roof’s Lifespan

Along with choosing a long-lasting flat roof material, choose the best flat roof company you can find to install it. Doing so will ensure you will receive the highest-quality roofing installation process. With this, your commercial building’s roof is more likely to last for its maximum lifespan.

In addition, you want to make sure that your roof receives proper maintenance. Consider hiring us to perform this service for you. For over 25 years, we have provided most of Wisconsin with unparalleled roof restoration services.

Contact us today by phone or email for a free price quote.