Monday, January 10, 2011

Hybrid Insulation Systems Give Best of Both Worlds in Performance

Courtesy of Lucas Hamilton, Manager, Building Science Applications for CertainTeed Corporation.

While making a presentation recently at the Oakland Space and Science Center in California, the topic of fiberglass versus spray foam insulation came up and was quickly followed by questions about hybrid insulation systems. It seems like a lot of people have hybrids on their mind these days.

One of the positives about spray foam is that the insulation itself is air resistant. The gas or air which does the majority of actual insulating is trapped in bubbles inside the plastic foam matrix and can’t be washed out by air flow. Now that we recognize the influence of air leakage on a home’s energy consumption, many builders and homeowners are trying to get their houses as “tight” as they can. Installing spray foams where air is leaking through the building envelope can reduce that flow rate. One of the issues people struggle with when considering foams as a solution has been their cost- they can have a significantly higher installed cost than fibrous insulations.

For this reason, in some markets, contractors are turning to hybrid insulation systems often referred to as flash and batt insulation. To fill a 2 x 6 inch empty wall cavity, first add a flash coat of closed cell foam on the exterior wall to a thickness of 1 -2 inches then take a low density batt to fill in the space before the drywall is installed. What you get is the best of both worlds – the inexpensive high R-value of the fiberglass batt combined with a smaller amount of foam which gives you the air tightening effects desired.

To read more, visit the CertainTeed blog