By: Jim Nugent, Regional Sales Manager
It has been very exciting to see the continued growth in the use of EPS in a wide range of below-grade, underslab, and frost protected foundation applications. The growth of ACH Foam’s brand of architectural grade insulation, Foam-Control Plus+ has been particularly impressive. Foam-Control Plus+ highlights the EPS material types from ASTM C578 that range from 15 psi to 60 psi, or as we like to call it “architectural grade” EPS. Beyond the applications previously mentioned, Foam-Control Plus+ is also being used is plaza decks, green roofs, cavity walls, precast concrete cores, and more.
For several years ACH Foam has been committed to educating the engineering and architectural design communities about the benefits of EPS rigid insulation and EPS Geofoam. In recent years our focus has been on below-grade and cavity wall applications where extruded polystyrene had long been the default specification. The primary reason XPS had been in so many specifications was the marketing of their ASTM water absorption data. In simple terms, the ASTM test used to evaluate water absorption of both XPS and EPS is a short term laboratory test intended for quality control guidelines for the manufacturers but in no way is indicative of the in-service performance of either material.
There is now a significant amount of data available to owners, architects, engineers and contractors that evaluates the performance of both EPS and XPS in below-grade applications. These evaluations are from real world projects, where EPS and XPS were installed on buildings for many years, then excavated and measured for water absorption, R-value retention, and permeability. Permeability is the ability to shed moisture (or not shed moisture in the case of XPS) during drying conditions and is a critical physical property that is often overlooked. All evaluations were done by third party testing laboratories.
This post does not allow me space to detail the results of each evaluation. You can certainly visit www.achfoam.com and review moisture bulletins 101,102,103,104, and 105 to review the findings. To summarize what you will learn from these moisture bulletins:
- When in service on buildings both EPS and XPS can absorb moisture beyond their ASTM data which will impact R-value; however, in many cases XPS absorbed significant amounts of moisture.
- EPS showed the ability to shed moisture during drying conditions while XPS did not as easily. Shedding moisture in drying conditions is a key factor to long term R value performance
- EPS out performed XPS in R-value retention when confronted with bulk moisture.
This eye opening data is the driving force behind the success of Foam-Control Plus+. Architects around the country are now specifying Foam-Control Plus+ where they had previously specified XPS. Contractors are also benefiting from the lower cost of Foam-Control Plus+, the handling advantages of installing larger pieces, and in some cases the ability to have custom sizes.
On a personal note this year I have been involved with a dozen Passive House projects where either Foam-Control Plus+ or EPS Geofoam was used in frost protected shallow foundations. (The similarities of these two materials is a topic for a future blog post.)
Passive House designers prefer the design flexibility and insulating properties of EPS for their super insulated shallow foundations. This is just one more example why Foam-Control Plus+ is the right choice for below grade and perimeter insulation.