How to Boost Energy Efficiency with a Built-Up Roof

built-up roof

Better energy efficiency could save companies around the globe $437 billion a year. Business owners and homeowners are rightly interested in ways to save energy. Lower energy use can significantly reduce utility costs, and it’s better for the environment.

Installing a built-up roof is one way to improve your energy efficiency. It can also give you more protection against fire, moisture, and storm damage. Learn more about the benefits of a built-up roof for your home or business.

What Is a Built-Up Roof?

A built-up roof is one of the most popular roofing systems for flat roofs. Built-up roofing involves layers of roofing material. Most built-up roofs have three or four plies.

The roofing system starts with a layer of insulation and a cover board. The installer then applies alternating layers of bitumen (asphalt) and ply sheets. Roofing felt and fiberglass are common choices for the ply sheets.

The final layer is either a mineral-surfaced cap sheet or bitumen covered with surfacing aggregate.

Installation of a Built-Up Roof

Hot mop installation is the traditional method for built-up roofs. The roofing crew pours hot asphalt onto the roof surface and mops it into an even layer.

Cold-applied asphalt is becoming more common than hot installation. Cold installation uses cold asphalt adhesives. The roofing crew can spray it on or use a squeegee.

Your local roofing contractor will partner with you to decide which application method best fits your commercial or residential roof.

How a Built-Up Roof Improves Energy Efficiency

The way a built-up roof is constructed helps boost energy efficiency in several ways. A built-up roof will reduce your cooling costs and can lower your heating costs as well.

Reflective Coating

Most built-up roofing systems have a reflective layer. This can qualify a built-up roof for cool roof status.

A highly reflective layer prevents the roof surface from absorbing the sun’s heat. It lowers the internal temperature of the building.

The reflective layer is usually either a white-coated cap sheet or an aluminum coating on the roof surface. A white coating is also an option, but the installation team must be careful to ensure it won’t yellow over time.

Multiple Layers

The use of an insulation layer combined with the other layers in a built-up roof contributes to energy efficiency. Integrating the layers together gives you a higher R-value and better thermal performance.

The layers reduce heat transfer in and out of the building. This makes the building more comfortable. It reduces the need to pay for heating and cooling the building.

Using a layer of gravel gives you even better thermal performance.

Other Protective Benefits of a Built-Up Roof

A built-up roofing system can protect your business against more than high energy costs. It can prevent damage from moisture, fire, and other threats.


Moisture is one of the main causes of roof damage. A built-up roof can be very effective at preventing moisture from entering. People have used bitumen for thousands of years for its waterproofing capabilities.

Built-up roofs have layered construction and minimal seams compared to other types of roofing. These features contribute to its protective qualities against moisture. If the top layer is damaged, the other layers continue to prevent water from entering the building.


A built-up roofing system can protect your building against fire damage. With aggregate as the top layer, it will usually meet the Class A standard. Class A is the highest fire resistance rating.

Bitumen can withstand significant heat before it will ignite. You can increase the fire resistance by ensuring that other parts of the roof system are fire resistant.

If the roof deck is made of combustible material, you can apply a fire protection coating. This can help you maintain a Class A rating even with a plywood roof deck. The roof insulation should have fire-retardant properties or resistance to high temperatures.

Using a cover board also improves the fire rating. A cover board helps prevent fire from getting to the insulation underneath.

High Winds and Other Severe Weather

Wind resistance is important because the wind load on a flat roof is more than for pitched roofs.

Built-up roofing systems have very good uplift resistance in extreme winds. Each ply of the roof adheres directly to the next without the need for fasteners. Fasteners cause stress points and penetrations that can reduce wind resistance.

The installation process can improve the wind resistance of your built-up roof. The roofers should ensure the metal flashing around the roof edges is attached as securely as possible. The fascia needs to be strong enough to resist wind uplift that would damage the flashing.

Pressure and Impacts

The layered construction of a built-up roof makes it a very sturdy roof. A durable roof surface is especially important for flat commercial roofs.

You likely have mechanical systems, HVAC equipment, or other machinery on the roof. The roof needs to support the weight of this equipment. It must also handle the foot traffic of your personnel accessing the roof.

A built-up roof will resist damage from falling debris, hail, or other types of impact. The gravel layer protects the roofing surface.

Cost-Efficiency of a Built-Up Roof

A built-up roof is a cost-effective option for flat roofs. The cost depends on factors such as:

  • Size of the roof
  • Materials
  • Complexity of the installation

You get a very good return on your investment. The average lifespan of built-up roofs is 20 years. They can last 30 years or more with regular inspections and maintenance.

Built-up roofs are low-maintenance compared to other types of roofs. You need to reapply the UV protection layer every five years or so.

Regular inspections will help you identify any potential problems before they turn into leaks. Your roofing contractor can repair most of these issues, avoiding the need to replace the roof.

Start Benefiting from a Built-Up Roof

A built-up roof has many advantages for your home or business. It improves your energy efficiency. It protects against fire, wind, and moisture.

You can trust Smith Roofing to install and maintain your built-up roof. Our professional team has experience in residential and commercial roofing systems. We’ve been serving our neighbors in northeast Indiana since 2001.

Contact Smith Roofing & Remodeling today for a no-obligation evaluation of how a built-up roof can improve the look and function of your building.