Roofing Insulation: Impact of Temperature on R-Value

By: Tamara Middleton, Sales Representative

Roofing3016_Page_1Most flat roof commercial buildings today use one of three insulations, polyisocyanurate (polyiso), extruded polystyrene (XPS) or expanded polystyrene (EPS).  These insulations are used above the roof deck and protected by the roof membrane.  Polyiso is the most commonly used of the three, this is due to its higher initial R-Value; however, not only does polyiso lose R-Value over time, its R-Value varies with temperature.  In reality all three roof insulations R-Value will vary based on the mean temperature, but how they vary is rather important.

Polyiso has a published R-Value of 5.6 per inch at 750 F mean temp.  XPS is published at R-5.0 per inch and EPS Type II is R-4.2.  The 750 F mean temp is based on testing using a 500 F differential, cold side at 500 F and warm side at 1000 F.

All three insulations have been tested extensively by BSC (Building Science Corporation) and the NRCA (National Roofing Contractors Association).  These tests have shown that all three insulations have changes in R-value as the mean temperature changes.  At a mean temp of 400F polyiso’s R-value drops to R-4.9, while XPS Type IV and EPS Type II increase to R-5.4 and R-4.6 respectively. As the mean temp drops to 250F polyiso’s R-value changes significantly to R-4.0, while XPS and EPS continue to improve at R-5.6 and R-4.8 respectively.  All the mean temperatures are determined using a 500F differential, so at 250 F mean the cold side is at 00F and the warm side at 500F.  At mean temps well above 750F all three have lower R-values.  At a mean temp of 1100F (cold 800 and warm at 1300), polyiso’s R-value is 5.0, XPS Type IV, R-4.7 and EPS Type II, R-3.9.

It has already been show and proven that Polyisocyanurate loses R-value over time, now we can see that polyiso also loses R-value at the temperatures drop.  We can also see the polystyrene insulations improve in R-value with decreasing temps.  Based on these tests by BSC and NRCA, when the outside temperatures drops roofs with polyiso insulation need to have at greater thickness than that based on a 750 F mean temperature.


Professional Roofing, “Testing R-values, Polyisocyanurates R-values are found to be less than their LTTR values”, March 2015

Building Science Corporation Information Sheet 502, “Understanding the Temperature Dependence of R-values for Polyisocyanurate Roof Insulation”, September 2013

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DuraTherm® Kitting Services Expanded Nationwide

By: Greg Aron, Regional Sales Manager

Screen-Shot-2012-02-28-at-11.08.43-AM (1)Back by popular demand, ACH Foam Technologies has expanded its DuraTherm® insulated shipping container fulfillment services, specifically its corrugated box kitting solutions to include a wider range of sizes across multiple nationwide manufacturing locations.  These items will  also be available on demand with shorter lead-times.

ACH Foam Technologies’ DuraTherm® kitting service locations include McCarran, NV, Denver, CO, Kansas City, KS, Washington, IA, Fond du Lac, WI, and Gainesville, GA. ACH Foam Technologies offers a full range of services for DuraTherm® Insulated Shipping Containers:

  • Engineering & Design
  • 3D Modeling & Prototyping
  • Testing
  • Fulfillment Services

Please contact your local ACH Foam sales representative for further details regarding available kitted solutions for your area.

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Geofoam at 11,000 Feet: Reaching New Heights

By: Terry Meier, Sales Representative

In the winter of 2015/16 Snowbird ski resort opened a new upscale cafeteria-style restaurant known as “THE SUMMIT”.

It is located at the top of the tram on Hidden Peak, 11,000 feet above sea level making it the highest year round alpine facility in North America.

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The 23,000 square foot facility offers stunning views of the Salt Lake Valley and 360 degree views of the surrounding area.

Over 9,100 cubic feet of EPS 22 Geofoam was selected as backfill for this facility. The Geofoam was placed between the existing tram building and the concrete retaining walls. By using Geofoam the contractor was able to greatly reduce the thickness of the retaining walls due to the elimination of lateral soil pressures.

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In addition to lateral soil pressure concerns the General Contractor, (Layton Construction), had a number of challenging problems building a structure on top of an 11,000 foot high peak.

Two of those challenges were: 1) how do we get building materials to the jobsite and 2)how do we accomplish that without damaging the environment?

Because Geofoam is so light, (1/100th the weight of conventional fill material), it was much easier to transport the numerous truckloads 3,200 vertical feet to the jobsite location.

Since the completion of the construction of this beautiful structure I have visited it many times on ski trips and to enjoy the restaurant. I also come back to take in the beautiful panoramic views of one of the most beautiful places on earth.

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Simple is Better

By: Jim Nugent, Regional Sales Manager


Many of us have heard the expression “spoiled for choice”. As consumers today we have so many choices for the products and services we use, and the construction market is no exception. Architects and engineers have thousands of products available to them for each CSI construction division. In division 7 (thermal & moisture protection), the construction division most relevant to ACH Foam, architects need to choose products for Roofing, Siding, Waterproofing, Sheet Metal, Exterior Claddings, Fireproofing and others. It is understandable that architects are not always quick to try new products when there are so many to consider.

Specifically in the area of thermal protection I would like to think that simple is better. For the purpose of this blog post let us consider this question; if an architect could only pick one material to thermally protect a building in addition to providing structural support for concrete slab or a paver system, what product would they chose?

Let’s look at the fiber insulations like fiberglass and mineral wool. These products are used regularly on the inside of above grade walls, occasionally rock wool is used in cavity walls. However these products would not work well, on foundations, underslab, or beneath waterproofing membranes. Limited compressive strengths and poor moisture management are the issues.

Extruded polystyrene is a product that is commonly specified for foundation walls, underslab insulation, and in cavity walls. XPS is available in limited thicknesses which makes it harder to use to meet the new continuous insulation (CI) code requirements. New independent insitu data is showing that XPS used in foundation applications or in horizontal applications, holds moisture which impacts long term R-value. Extruded polystyrene is not very practical for use under roof membranes. The thin layers combined with the difficulty to create tapered XPS systems makes it impractical in roofing applications.

Polyisocyanurate (Polyiso) is commonly used in cavity walls and under roof membranes. Polyiso is available in a wide variety of thicknesses which helps meet changing CI R-value requirements but it has never been a good choice for foundation walls or underslab insulation due to issues with moisture retention and limited compressive resistance options.

New independent data from the National Roofing Contractors Association (NRCA) regarding the temperature sensitivity of polyiso is compelling. The roofing industry is learning that in cold climates the R-value of polyiso drops. At 25 degrees EPS actually has a higher R-value than Polyiso.

That brings us to EPS and Foam-Control® and Foam-Control PLUS+® below-grade insulations offered by ACH Foam Technologies. Starting at the foundation and underslab, independent testing shows Foam-Control PLUS+® is a great choice. The ability of Foam-Control PLUS+® to shed moisture in drying conditions makes it ideal for wet environments. With compressive strengths of 25, 40 and 60 psi Foam-Control PLUS+® is ideal for underslab and pedestal paver projects. Foam-Control® and Foam Control Plus+ are available in a wide range of thicknesses making it easier to meet CI requirements in cavity walls or other wall insulation applications, and also has many NFPA285 approved assemblies.

Lastly, Foam-Control® and Foam-Control PLUS+® EPS roof insulations are proving to be the right choice under roof membrane applications as well as above membrane horizontal applications. Larger pieces for tapered systems are outperforming polyiso R-values in cold climates, making EPS ideal under roof membranes. High compressive strengths, larger pieces, and better bulk moisture management make it ideal for above membrane applications in plaza decks, green roofs, and split slabs.

Initially the premise of only using one rigid insulation to thermally protect a building, may have seemed funny, but if you think about how this could simplify the specification for an architect this premise has serious merit. A very strong case can be made that simple is better and Foam-Control® and Foam-Control PLUS+® can meet all the thermal protection needs of a building.

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Join ACH in Chicago for PackExpo 2016

By: Chris Benson, Packaging Specialist

2016_PACK_EXPO_International_LogoPackExpo is rapidly approaching as this year seems to be flying by.  The 2016 PackExpo will be Chicago, IL November 6th through the 9th at the McCormick Convention Center.

ACH Foam Technologies welcomes you attend and to stop by our booth at Upper Lakeside Center #E-6716  . We will have samples of our EPS manufacturing capabilities to show off along with a few of our highly knowledgeable and experienced sales team members to answer any questions.

For over four decades ACH Foam Technologies has been a leader in Expanded Polystyrene (EPS) manufacturing for packaging and industrial applications. With 8 manufacturing facilities across the United States, our customers have found ACH to be conveniently located, market competitive pricing on all our products, and a valued source to assist with any packaging or OEM solutions your company may need.

Please stop by the ACH Foam booth #E-6716 and meet our experienced and dedicated packaging team. We look forward to meeting you and working on a cost saving packaging solution that will meet your company’s needs.

We look forward to seeing you in Chicago!

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