A split image showing several commercial roof insulation options.

The importance of good commercial roof insulation is often overlooked. More often than not, business owners don’t worry about the quality of the insulation products installed in their commercial buildings. But this is a big mistake that could lead to costly energy bills. Even worse, it could cause damage to your building due to built-up mold or mildew.

You need to pay just as much attention to the quality of your insulation as you do your roofing materials – after all, they play an important part in protecting your business. Let us help you understand the difference between the different types of insulation options so you can select the best one for your building.

The Importance of Commercial Roof Insulation

If your commercial roof insulation isn’t good enough, it can cost you more than just making your building a little drafty. Commercial insulation is essential not only for comfort reasons but also for energy efficiency. Proper insulation maintains a comfortable indoor temperature and can help lower your heating and cooling costs – which is also important for the environment.

Without proper insulation, HVAC machines have to work harder to maintain temperatures inside your building. This strain may cause them to fail much earlier than they should.

Not only that, but proper insulation is important when it comes to preventing moisture from entering your building. If it fails to do so, you risk the health of your building and any of the machines within. Poor insulation can also increase the likelihood of rot in your roofing material, as well as ice dams that could threaten the health of your roof.

Investing in high-performance insulation can help save you money in the long run — keeping your most valuable assets protected.

How We Rank Commercial Insulation

Commercial insulation is graded on several factors that indicate how well it protects your commercial building and how well the insulation system fulfills regulatory requirements. There are many qualities that roofing contractors and other experts look at when determining the quality of insulation products.


R-value represents thermal resistance. This category judges how well insulation products resist heat transfer. The higher the R-value, the higher the resistance, the higher the insulation’s performance.

R-value rates start at R-1 and can increase to R-30. If insulation is rated R-1 to R-5, it has low thermal resistance. R-6 to R-15 is considered to be moderate. Insulation has a high R-value if it is rated R-16 and above.

Keep in mind that the R-value is additive, meaning it is calculated based on the thickness of the insulation or its individual layers.


The density of insulation is important in heat transition resistance and soundproofing. Typically, the higher the density, the better the protection and energy efficiency.

Fire Resistance

Insulation products are tested for their fire resistance. Those with high ratings in this regard can help contain flames and slow the spread of the fire.

Moisture Resistance

It’s important that insulation be resistant to moisture and water vapor transmission. Commercial insulation materials are tested to see how durable they are against moisture and rated based on their performance.

Building Code Compliance

Insulation is also rated on how well it meets building code compliance. Building codes are set at the state and local levels but often share similarities in safety requirements for commercial buildings.

Popular Roof Insulation Materials

There are a few commercial insulation roofing products available on the market. The most popular materials are made of fiberglass, foam boards, mineral wool, spray foam, polystyrene, or polyiso. Each comes with its own unique characteristics that are important to understand when selecting insulation for your commercial flat roof.

High-Density Extruded Polystyrene (XPS)

XPS is a rigid foam insulation made from resin derived from petroleum. It has a closed-cell structure that gives it high-performance moisture resistance. This makes it ideal for commercial buildings in humid climates or other applications where moisture control is crucial. Another perk of XPS is its high compressive strength, which is important if your roofing insulation is exposed to a lot of pressure.

Its R-value is rated between 4.5 and 5.0 per inch of thickness and decreases over time. Depending on its thickness, XPS offers fairly good thermal insulation that can help increase your building’s energy efficiency. Still, you may see a drop in performance as time goes on. For the environmentally-minded, it may not be the best choice since it’s derived from petroleum.

High-Density Expanded Polystyrene (EPS)

EPS insulation boards have an R-value similar to XPS. Like XPS, it’s not the most eco-friendly type of insulation product due to its manufacturing process. It also has limited resistance to fire and is particularly vulnerable to solvents.

However, its light weight makes it easy to install, and it has a high moisture resistance rating. It’s also one of the more affordable options when it comes to insulation materials.

Mineral Wool

Mineral wool is made from natural or synthetic materials such as basalt, diabase, limestone, or blast furnace slag. The R-value of mineral wool can vary based on the products used for its formation but typically ranges from R-3 to R-4 per thickness of the board. The higher its density, the higher its R-value tends to be.

Overall, it’s a very durable material that doesn’t deteriorate over time like XPS. It’s fire resistant, moisture resistant, and offers good sound absorption. A lot of the drawbacks of mineral wool have to do with its installation. It can be heavy and rigid, making it hard to install, and the material causes skin irritation.

Spray Foam

Spray foam comes from a mix of polyol and isocyanate. The polyisocyanurate is applied with a spray gun. You can find spray foam insulation with both open-cell and closed-cell structures. The closed-cell structures tend to have a higher R-value than the open, ranging from R-6 to R-7 per inch of thickness. The open cell typically has an R-value of R-3.5.

Closed-cell spray foam offers high-performance thermal resistance and air and moisture control. On top of that, it has a long lifespan. Closed-cell is one of the more expensive insulation materials on the market, but it’s a sound investment thanks to its long-term performance. It is important to have it installed by highly skilled roofing contractors, as some compounds release volatile fumes. Proper handling and ventilation during installation are a must.

Polyiso (PIR/ISO)

Polyiso insulation is made from a reaction of isocyanate and polyol and fiberglass or foil facer material. The reaction creates a rigid foam board that is lightweight and easy to handle while also providing high thermal insulation. Its R-value ranges from R-6 to R-7.2 per inch of thickness. It’s treated with fire-retardant additives that also give it a boost in fire resistance.

The facer material is moisture-resistant, but regular exposure to water makes it less effective over time. This insulation material is also on the more expensive end. Like EPS and XPS, its manufacturing method isn’t the most environmentally friendly.

Get the Most Out of Your Commercial Roofing System

From your roofing membrane to your commercial roof insulation – quality products require quality installation. If you’re looking to upgrade your insulation and roofing system, you need to work with the best to protect your biggest asset.

At TEMA, we have 50 years of experience providing premium roofing assembly services. Whether you need a low-slope roof repair or want to upgrade your roof to EPDM, PVC, or metal – we’ve got the skills you need, and that’s a warranty-backed guarantee. When you need a roofing contractor, contact us and put TEMA on your team.