Roof Insulation Performance in Cold Climates

By: Pat Austin, Sales Representative – Architectural Products

In the northern parts of the United States and Canada, insulation usage is largely designed to keep buildings warm. In Wisconsin, where I live, our average year-round temperature hovers around 45°F, depending on which part of the state you live in. This means insulation performance is very important when temperatures drop.

Recently, the National Roofing Contractors Association (NRCA) conducted research on the cold-temperature performance of polyisocyanurate insulation. The results were both surprising and disappointing considering the volume of polyiso installed in heating climates. To summarize the NRCA’s findings, polyiso performs at R-5.55 per inch at 75°F, and drops as the temps fall.   At 40°F polyiso is not quite achieving an R-5.0 per inch and at 25°F it’s down to R-4.0 per inch.

Read more in the NRCA March 2015 Tech Talk Bulletin

To further study the impact of this in northern climates, I looked at the heating degree days in Wisconsin, as compared to the temperature curves in several cities across the state. It turns out that we spend upwards of 75% of our energy budget heating on days averaging 40°F or below and over 50% of our dollars on days 25°F or below. Insulating with a product that loses R-value as the temperature falls makes zero sense and costs money.


Comparatively, Foam-Control® and Foam-Control PLUS+® EPS roof insulations gain R-value as temperatures decrease. Our Foam-Control PLUS+® 150, for instance, increases from R-4.2 per inch at 75°F to R-4.8 per inch at 25°F. We gain R-value when we need it the most! And best of all, EPS provides this performance at a cost-savings to the owner.

In northern climates, when designing insulation envelopes to keep our buildings warm in the most cost-effective manner, the choice is clear. Foam-Control® and Foam-Control PLUS+® EPS roof insulation provides performance, saves money, and keeps you warm!

About Pat Austin

BSIE from Marquette University in 1986, MSMSE from UW Madison in 1989. General contractor for 13 years before joining the ACH Foam team in 2007. Married to Kelly, with four sons.
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