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  • Writer's pictureUnited Materials

A Brief Explanation of Built Up Roofs

Updated: Nov 25, 2023

Built up Roofs offer Many Benefits

As a business owner or building manager, you can’t be expected to know a lot about commercial roofing. But when it comes time to replace your roof, the term “built up roof” may come up. Here’s some information that helps explain what a built up roof is and the benefits these roofs offer.

A Multi-Layer Option

A built up roof is made of layers of material, built one atop the other. This layering creates a very durable roof. Built up roofs are commonly found on buildings with flat roofs or roofs with slight slopes and are an excellent choice for demanding applications.

A built up roof starts with a layer of durable cover boards that serve as the base of the roof. These cover boards can be installed over a layer of insulation, which increases the thermal efficiency of the roof.

Alternating layers of coated fabrics such as felts or mats that are covered with a layer of bitumen are placed over the cover boards. Hot bitumen is usually used, but cold adhesives are also available.

A top layer caps off the roof. Top layers can be gravel or other materials that are adhered to the roof with bitumen. Special reflective coating systems can also be used as top layers.


Built up roofs offer a number of impressive benefits.

  • Stable Surface – Built up roofs provide a stable surface for mounting roof-top mechanical equipment, roof decks, etc.

  • Wind resistant – The multiple layers create a strong roof that is very resistant to uplift caused by high winds.

  • Water Resistant - The multi-layer system offers excellent protection from water.

  • Energy efficient – When combined with insulation, built up roofs can help lower heating and cooling costs. Reflective coating systems and light-colored top layers, such as white gravel, can also increase the roof’s ability to reflect the hot rays of the sun.

Your Local Roofing Experts

The professional staff at United Materials are your local built up roofing experts. Our roofs provide excellent, long-term value.

For 99 years, United Materials has installed, maintained, and repaired commercial roofs throughout the Denver area and the Rocky Mountain West. Many of the most notable buildings in the region are protected with roofs from United Materials. We can install the roof you need.

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