What is expanded polystyrene (EPS) exactly?

By: Tamara Middleton, Sales Representative – Architectural Products

EPS (Expanded Polystyrene) is a closed cell insulation manufactured by expanding a polystyrene polymer.  Originally discovered in Germany by Edward Simon by accident. Polystyrene is extracted from crude oil along with many other products.  4% of crude oil is used for plastics and 0.1% of the plastics is used for polystyrene. The production process uses a pure hydrocarbon, which does not contain halogens and does not damage the ozone layer.


Polystyrene’s main component is styrene (C8H8), derived from petroleum and formed by a reaction between ethylene (C2H4) and benzene (C6H6).  The styrene is polymerized by heat and beads are formed by suspension.  These tiny beads are expanded using special blowing agents, to achieve the right density.  This pre-expansion involves heating the beads with steam or hot air.  The pre-expanded beads are then aged for 24 hours, allowing the air to diffuse into the beads, cooling and drying them.  Once aged, the beads are molded, using low-pressure steam, expanding them again and fusing them.

While waste or used EPS can be incinerated creating only carbon dioxide and water if done correctly, it is usually recycled.  Recycled EPS can be used in many office products, hangers, CD cases, and even crown molding.  According to the EPS Industry Alliance, 125 million pounds of EPS were recycled in 2013, with a commercial recycling rate of 34 percent.


  • The Balance, ‘Introduction to EPS Recycling’ by Rick LeBlanc, October 20, 2015
  • About.com, ‘What is EPS – Expanded Polystyrene’ by Todd Johnson
  • Made How, ‘Expanded Polystyrene Foam (EPF)
  • Jayshree Machines & Tools, ‘What is EXPANDED POLYSTYRENE (EPS)’
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Hitting the (Roofing) Slopes

By: Jim Nugent, Regional Sales Manager

With snow season here many are thinking about ‘hitting the slopes’ to go downhill skiing. In the commercial insulation business, slopes aren’t nearly as fun or exciting but a critical component of tapered roof insulation design. There are many new code regulations this time of year that will have an affect on the way roofing contractors bid projects which could potentially increase their costs.

Specifically, there are new developments in the 2012 International Energy Conservation Code (IECC) on how commercial roof insulation contributes to R-value when tapered insulation is required. Many states have already adopted the 2015 version of the code; however, some states are just now beginning to adopt the code.

Code language can be confusing and that is certainly the case when it comes to how the code explains the way tapered insulation contributes to the R-value of a roof assembly. To simplify, states that have adopted IECC 2012 or newer comply with the following:

When insulation is sloped ¼” per foot you must be at the code required R-value 4’ from the drain. If the insulation is sloped 1/8” per foot you must reach the minimum R-value 8’ from the drain.

For example, in the state of Illinois where I do business the required R-value on a commercial roof is R30. This means the tapered system would need to reach the required R30 either 4’ or 8’ from the drain.

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Due to this code change, it’s not hard to imagine that tapered systems are getting thicker and more expensive. Foam-Control® and Foam-Control® PLUS+® tapered roof insulation is your solution:

roof9• Depending on the material type Foam-Control® and Foam-Control® PLUS+® costs 35-40% less than the widely used Polyiso, while offering a comparable R-value.
• A Foam-Control® or Foam-Control® PLUS+® tapered system can be designed in 1 or 2 layers which can dramatically reduce the number of squares rather than using a multiple layer polyiso system.
• Reducing squares reduces labor costs and adhesive costs.
• Both Foam-Control® and Foam-Control® PLUS+® offer compound hip and valley pieces which dramatically cut waste and labor time.

As you can see there are many advantages of tapered Foam-Control® and Foam-Control® PLUS+® roof insulation. ACH Foam Technologies also offers tapered design service in many of our manufacturing locations. We will also accommodate other taper designs.

Contact your local ACH Foam Technologies roofing expert to quote your next project.

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The Load Reduction and Arching Effect of Geofoam on Culverts & Pipelines

By: Terry Meier, Geofoam Specialist

It has been stated that an amateur sells products, a professional sells solutions to problems. One of the many problems that Geofoam solves is vertical load reduction on underground structures. The problem of earth pressure on deeply buried utilities has a great practical importance in constructing embankments over utilities.

EPS Geofoam blocks have been used for load reduction on buried utilities since 1988. The 100 to 1 weight ratio difference between conventional fill material and Geofoam brings about a significant load reduction on underground structures such as pipelines and culverts. In addition to its ultra-light weight advantage Geofoam has well defined compressibility characteristics which allow for controlled compression and yielding.

Copyright ACH Foam Technologies' EPS Geofoam

Geofoam also creates a compressive soft zone layer above the utilities.  The soft zone (Geofoam) compresses more than the surrounding fill and thus induces positive arching above the utility. Earth pressure on deeply buried utilities is greatly affected by this arching effect. Arching diverts soil pressure away from the utility thus reducing expected vertical earth pressure.

postitive-arching-effect arching-effect negative-arching-effect

A better understanding of the arching effect of EPS Geofoam on buried utilities has been obtained from field study full scale test measurements. Four instrumental field tests using Geofoam for load reduction on buried utilities were performed over a four year period. The Geofoam was placed above the utilities. Hydraulic pressure cells were placed at various locations above and adjacent to the utility to measure vertical and horizontal earth pressures.


Using Foam-Control® Geofoam was successful in reducing the vertical loads on the buried utilities. The average measured earth pressure above the crown of the utility ranged from 23% to 45% of the overburden pressure depending on the type of backfill which was used. Long term monitoring of the installations indicate no increased pressure on the buried utilities. Once again Foam-Control® EPS Geofoam is indeed a problem solver.

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Key Features to Evaluate When Selecting Roof Insulation

By: Brent Tanimoto, Sales Representative – Architectural Products

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With 2017 upon us and New Year’s resolutions in full swing, it time to consider ACH Foam Technologies’ Foam-Control® Plus+® architectural roof insulation needs?

Let’s take a moment to review a few of the advantages to using Foam-Control® Plus+® in your roofing application:

    • Expanded polystyrene (EPS) is highly customizable and versatile. Unlike other rigid insulations, EPS is available up to 40 inches thick and can be factory cut to nearly any size or shape. Because of this, fewer layers are required to achieve R-Value, resulting in less applied squares and significant labor savings.
  • Available in four different compressive strengths, up to 60 psi, Foam-Control® Plus+® is an extremely durable material and offers the highest R-Value per dollar, with up to 30% savings over tapered ISO systems.
  • Unlike XPS and ISO, EPS does not contain blowing agents, which results in a loss of R-Value over time. This is known as thermal drift and in January 2014, the roofing industry changed LTTR R-Value testing which shows that XPS & ISO can lose their thermal stability over time. This did not affect Foam-Control® Plus+® insulation.
  • Foam-Control® Plus+® is compatible with almost all major single-ply roofing systems and meets or exceeds ASTM C578 requirements.
  • EPS is a closed cell insulation that not only has superior moisture resistance, but has a high drying potential with the ability to quickly release any absorbed moisture.
  • ACH Foam Technologies’ Foam-Control® Plus+® architectural roof insulation is environmentally sustainable. It is 100% recyclable and may contain up to 25% recycled content. Our material contains no dyes, formaldehyde or HCFC’s and can contribute towards LEED® credit requirements.

For more information on roofing products and applications visit ACH Foam Technologies website. On behalf of everyone at ACH Foam Technologies, we wish you a happy and prosperous New Year!

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You Can Trust Geofoam

By: Nick Harvill, Sales Representative

nick-harvillGeofoam is a cellular plastic material that is strong with a very low density, one percent of traditional earth materials. Geofoam has been used in engineering and geotechnical applications worldwide for more than 30 years. Yet many engineers seem to be leery of the load carrying capacity of Geofoam and specify the highest grade to be cautious.

EPS Insulation is specified using ASTM C578. It lists the physical properties of each grade and the insulation value. The compressive strength is listed at 10% deformation. This value is listed for comparison purposes of various insulations and is measured near the failure point. For loading purposes, it has been recommended that 1/3 of this value be used. But for Geofoam use, we have ASTM D6817. It lists the load carrying capacity of each grade of Geofoam at 1% deformation. The compression test is also different from the Insulation compression test to better simulate Geofoam use. This takes the guesswork out of designing for loads.

However, many Engineers do not seem to trust the data. Recently, one engineer specified EPS 46, a material capable of carrying 2680 Lbs./sf, under a 4” retail slab supporting only the store and its occupants. Usually an application like this would require EPS 15 at 520 lbs./sf capacity. EPS 15 is the most commonly specified Geofoam grade; used in stadium and theatre seating, slab on grade fill and other areas where the Geofoam is only needed to provide low load fill. Not only did they specify EPS 46, but they specified 6” steel reinforced knee walls every 5 feet to the existing slab. Under this construction, the Geofoam is not really carrying any load at all and EPS 15 would have been more than sufficient.

Geofoam provides High Strength. It has Predictable Performance with No Settlement. Densities are engineered for applications. If the load approaches the limit of a grade, it is economic to increase to the next grade for safety. Geofoam has Low Water Absorption and is economical, especially when the correct grade is used. Geofoam is:

  • Easily Modified on Jobsite
  • Variety of Sizes & Shapes
  • Termite Resistant
  • Environmentally Friendly

Geofoam has been used in engineering and geotechnical applications worldwide for more than 40 years. In a correctly designed application, it will perform for the life of the project.

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