Photo courtesy of Insulfoam

Since the 1930s, the commercial building industry has utilized expanded polystyrene (EPS) rigid foam insulation to achieve high-performance alongside cost-effectiveness. A critical component of a building envelope, insulation is more important than ever as today’s commercial contractors aim to ensure compliance with stringent code-required R-values, while staying under budget.

Contractors can economically increase a building’s R-value by using ultra-lightweight, moisture-resistant EPS panels that are customizable to meet project needs. EPS shows off its high-performance capabilities in all areas of the building, including walls and below-grade, due to its ability to increase thermal resistance, provide moisture resistance, and meet required compressive strength.

Continue reading to gain further insight into the advantages of building with EPS as Insulfoam expert Chip Coughlan addresses commercial contractors’ frequently asked insulation questions.

Why is EPS insulation right for my job?

COUGHLAN: EPS insulation is typically engineered to a 4-foot x 4-foot x 8-foot block and can easily be cut down to the exact size needed for the job. Because of the flexibility of the product afforded by its large size, EPS is expertly suited for an array of commercial jobs. Commercial contractors can install the solution via an exterior wall, below-grade and in all other parts of the building envelope.

How is this insulation cost-effective?

COUGHLAN: Often times, contractors require multiple layers of insulation to meet R-value mandates. Below-grade applications, for example, may actually require several feet of insulation to fill voids under slabs.

In contrast, EPS is available in large blocks, and professionals can cut the material to satisfy virtually any project need. This makes it possible to elevate R-values without the material or added labor costs of building up multiple insulation layers on site. EPS’ customization capabilities call for less material handling, and its lightweight nature results in quick installation—all of which aid in accelerating jobs’ timelines, contributing to contractors’ ability to stay in the black.

Is EPS water-resistant?

COUGHLAN: When contractors have a project that will likely be exposed to moisture, EPS can rise to the challenge due to its water-resistant properties. For example, during 15 year in-situ testing below-grade, where wet soil and freeze-thaw cycles are commonplace, EPS saw only 4.8 percent water absorption. The material further delivered 94 percent of its specified R-value after the allotted time.

These long-term performance advantages make EPS a preferred choice for contractors looking for a reliable insulation material.

Is the material easy to work with in the field?

COUGHLAN: Crews can simply mechanically fasten EPS insulation directly to the application using cap screws, cap nails, staples, or adhesives. And, thanks to its light physical properties, teams can easily maneuver EPS insulation into the proper position.

What adhesives, caulk, and insulation tapes do you recommend when working with EPS?

COUGHLAN: There are a variety of compatible adhesives, caulk, and insulation tapes available on the market today. Keep in mind—water-based, urethanes and polyether’s adhesives work best, and should not use solvents that could deteriorate the insulation.

Ultimately, the choice of adhesives, caulk and tape for a contractor’s insulation job depends on the application at hand.

How can the material meet continuous insulation requirements for walls, optimizing energy-efficiency?

COUGHLAN: The key to optimizing energy-efficiency is to create a virtually airtight envelope by eliminating thermal breaks. Because manufacturers can produce EPS blocks in large sizes to cover an expansive wall, there are going to be fewer air gaps and reduced thermal bridging from fewer connections. This affords contractors the ability to meet stringent continuous insulation requirements without racking up material costs.

And, speaking of energy-efficiency, EPS’ thermal properties will remain stable over its entire service life. Some EPS manufacturers are even able to guarantee R-value over 20 years.

Why should contractors insulate below-grade, and what are some key considerations to keep in mind when doing so?

COUGHLAN: Since uninsulated concrete provides a thermal bridge between a commercial building’s heated interior and the relatively cooler earth surrounding the building or through exposed slab edges to the outside air, blocking that heat flow with insulation is critical. Below-grade insulation also helps mitigate moisture to reduce interior condensation on foundation walls. Or, when installed on the exterior, insulation helps prevent freeze-thaw cycling damage.

That being said, it’s important for contractors to determine the most appropriate insulation method for their application. For example, insulating below a concrete slab is much different than insulating below a commercial-grade freezer.

Secondly, professionals must judge the appropriate compressive strength needed for the job. EPS’ flexible product offerings allow manufacturers to meet a range of compressive strengths for a project, up to 60 psi.


Insulfoam, one of the nation’s larger manufacturers of block-molded EPS, recommends a few insulation best practices to help contractors get the most out of working with EPS:

  • When using an unnecessarily high-strength insulation, contractors end up paying for something they don’t really need. Since EPS is available in a range of compressive strengths (from 10 to 60 psi), using it in below-grade applications can lower material costs. Contractors should keep in mind that because Insulfoam provides countless variations of thicknesses to fit the application, they will likely end up installing fewer layers of insulation.
  • Unlike insulation that fills wall cavities between the studs, crews apply EPS rigid foam insulation over the entire wall to provide a continuous thermal layer making it an ideal choice for wall applications.
  • A simple way to check the long-term thermal performance of any insulation is to review the manufacturer’s warranty. Insulfoam proudly warrants 100% R-value for 20 years.
  • With extensive building code requirements, it can get confusing deciding which product is best for the job at hand. If contractors have questions about code requirements or simply want to learn more about their insulation options before getting started, connect with an Insulfoam rep or contact Insulfoam directly.


EPS is going to be commercial contractors’ best bet when it comes to delivering desirable performance capabilities such as moisture retention, R-value stability and compressive strength. And, the rigid foam offers these high-performance capabilities without breaking budgets. It’s a no-brainer.

for more information:

Chip Coughlan is the Southeastern and Mid-Atlantic territory manager for the Insulfoam location in Lakeland, Florida. He can be reached at

Modern Contractor Solutions, June 2020
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