Best Roofing Systems for Flat Roofs


When starting a roofing project, it can be overwhelming. There are many types of roofing systems for all of the types of facilities out there. A roof type that would work for a low slope roof may not work as well for a steep slope roof on a residential home. It’s important to know what works best for your facility.

A highly trained contractor will be able to help you choose the best type of roof system for your facility, but it never hurts to be prepared!

At West Roofing Systems, we have been helping customers for decades choose the right roof for their building and their budget. We want everyone to feel empowered when they start getting quotes from their contractors. In this article, we break down the five most common types of commercial roofing along with their average costs* and advantages.



Spray Polyurethane Foam Roofing

Spray Polyurethane Foam (SPF) is an eco-friendly roofing option for commercial, industrial and manufacturing facilities. Spray Polyurethane Foam, more commonly referred to as SPF, is a material that is sprayed as a liquid so it can expand into a foam, creating a solid layer across an existing roof.

Read More: Spray Polyurethane Foam (SPF) Roofing: Installation & Performance

While SPF roofing is not the most known type of roofing material, the technology has been around since the early 1960s for industrial, commercial, and residential facilities. An SPF roofing system can be used in any climate, and when correctly installed and maintained, can last over 50 years.


Spray Polyurethane Foam Cost

For an average 20,000 sq. Foot commercial roof, it will usually cost between $4.00 and $7.00 per square foot* in materials and labor to install a typical SPF roofing system. This price range is for an SPF roof of average thickness and building structure.

Read More: Cost of a Spray Polyurethane Foam Roofing System


Spray Polyurethane Foam Savings

The energy efficiency and environmental sustainability can lead to lower life-cycle costs to install and maintain an SPF roofing system. When installing an SPF roofing system, in some instances, there is no need to strip the existing roof. This saves money on labor and debris removal. The longevity of a properly maintained system can be beneficial in the long run when there is no need for replacement.



Single-Ply Membrane Roofing

Single-Ply Membrane EPDM Installation

Single-Ply Membrane is a time-tested roofing option for commercial, industrial and manufacturing facilities. Single-Ply Membranes are sheets of rubber and other synthetics that can be ballasted, mechanically fastened or chemically adhered to insulation creating a layer of protection on your commercial facility.


Single-Ply Membrane Insulation Choices

After the existing substrate is prepared, either by cleaning or removing the existing roof, the insulation is installed. In general, two layers of insulation are used.

There are a few types of insulation options the facility manager/owner can to choose from:

  • Polyisocyanurate (Polyiso) – Polyiso is the most commonly used insulation for roofing. It’s a rigid material that can be cut to size for installation. The R-Value for Polyiso lasts longer, and the aged R-Value is still higher than EPS and XPS.


  • Expanded Polystyrene (EPS) – EPS can be used for roofing, walls or floor insulation, but more commonly used with concrete. You get more R-Value per dollar with EPS being the lowest cost insulation choice.


  • Extruded Polystyrene (XPS) – XPS insulation can be found in blue, pink or green and is most commonly used for wall insulation. This is probably what you think when you hear insulation because it is the middle of the road regarding cost and R-Value.


Single-Ply Membrane Cost

While Single-Ply Membrane Roofing is one of the most well-known types of commercial roofing material, there are several types to fit your budget and facility needs. For an average 20,000 sq. Foot commercial roof, it will usually cost between $3.50 to $7.50 per square foot for EPDM and $3.50 to $6.50 per square foot for TPO*, including materials and labor warranty.

Read More: Cost of Single-Ply Membrane Roofing




Metal Roofing

Metal Roofing is one of the oldest commercial roofing systems on the market. Most metal roofing systems use corrugated galvanized steel, although other materials such as aluminum or tin can also be used.

Since metal roofing material is rather light in weight, it can be installed right on top of the existing roof. After a metal roofing system is installed, a coating can be added for waterproofing, rust protection, and UV protection.


Metal Roofing Cost

For an average commercial roof, it will usually cost between $5.00 and $10.00 per square foot* in materials and labor to install a typical metal roofing system. This price range can change depending on the type and style of the metal panels you choose.



Built-Up Roofing

Built-Up Roofing Systems have been in use in the U.S. for over 100 years. These roof systems are commonly referred to as “tar and gravel” roofs. Built-up systems are installed by alternating layers of asphalt or tar and supporting fabrics directly onto the roof. You can choose the number of layers (or plies) that are installed. The final layer of a built-up roofing system consists of stone or gravel.


Built-Up Roofing Cost

For an average commercial roof, it will usually cost between per $5.50 – $8.50 square foot* in materials and labor to install a typical built-up roofing system. This price range can change depending on the materials you choose.


West Roofing Systems, Inc. installs sustainable and efficient roofing systems for commercial, industrial, manufacturing and municipal buildings. In over 37 years, we have installed over 57,000,000 square feet of commercial roofing, and our expert team is ready to help you.

If you are looking for maintenance, repair or replacement of your facilities roof, fill out our quote form for your free no-obligation commercial roof quote from our team of experts.

*Reported costs are not quotes, they are approximate costs. Please contact West Roofing Systems to request a quote and proposal for your roof.


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Author: Jack Moore

Jack Moore is President and CEO of West Roofing Systems, Inc. With 21 years of SPF Roofing experience, West Roofing Systems has received numerous accolades for his leadership in the commercial roofing industry, including 18 industry excellence awards from the Spray Polyurethane Foam Alliance. He is an active member of the National Roofing Contractor’s Association and the Spray Polyurethane Foam Alliance.

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