By: John Myers, Sales Representative – Architectural Products
Wait a minute! You mean the published R-Value is not always an accurate reflection of the actual performance I will receive? How does that happen?
The reality of published R-Values for rigid foam insulation is somewhat like the estimated fuel mileage on the sticker of your new car. Rarely is it an accurate reflection of your actual mileage. Driving conditions, your lead foot, and other real life conditions will have an effect on your car. As will the quality of the fuel you put in your tank.
In the world of rigid insulation, the factors to consider are as simple as the method of production. First to consider is that all foam insulation boards are made from a type of plastic. The raw material is expanded into blocks then cut into sheets OR extruded into sheets. When the production process requires the use of gasses to extrude a raw material, the initial R-Values of the finished product can be overstated. The gas that is used for expansion is not permanent, and is eventually replaced with atmospheric air that rem
So when do we measure the R-Value? Just like the auto industry, the R-Value is calculated at the best possible condition, and in the case of rigid insulation it is at the time of manufacture. This is not always the R-Value you can expect to receive in the field, as verified by outside entities such as the National Roofing Contractors Association and Building Science to name a couple.ains for the life of the product. At that point the R-Value becomes stable.
What is the answer? There is one type of foam that does not temporarily capture gas in the manufacturing process. Expanded Polystyrene (EPS)
does not inject gasses into the product and therefore arrives at the job with an R-Value that will remain constant throughout its lifetime. It is manufactured with trapped atmospheric air and thus never changes its R-Value.
Take a drive with EPS Insulation and know that you will enjoy the consistent performance as your insulation of choice for below-grade, roofing, and cavity wall applications. You will feel confident that the R-Value you thought you were designing with or purchasing is exactly what was stated on the sticker.