Insulation R-Value: the minimum allowed or as much as possible?

I recently reviewed a beautiful house that was in the process of being built. Clearly, no expense was spared to make this a beautiful home. During the walk-through, I asked the builder how much insulation was being used in the attic. He replied ResCheck (a code compliance energy modeling tool) says R-30." He seemed quite proud of that and we continued our evaluation.

The Department of Energy has been studying homes and insulation levels for decades, and they recommend R-38 for our area. In fact, most green minded builders prefer even more due to the very high temperatures found in attics. And yet builders are only looking to satisfy minimum code requirements.

While the argument is often made that adding more insulation doesn't appreciably reduce the total energy required to heat and cool a home, the fact remains that the recommended R-38 attic insulation results in 27% less energy loss through the attic than does R-30. This affects your utility bills as well as your family's comfort.

In fact, the real situation is worse than the numbers show. Fiberglass batts, by far the most common insulation material, are difficult and time consuming to install properly, so most builders install fiberglass in a way that can reduce the R-value significantly. to do it right, the fiberglass must be carefully cut and fitted so that it isn't compressed or gapped. In addition, while not widely known, fiberglass loses R-value as the temperature drops, so it provides, about 30% less R-value when it is the coldest outside.

If you are planning to insulate your home, there are other insulation products that can be much more effective than fiberglass. Blown in products such as dense packed cellulose and spray foam give more consistent R-values in typical installations. They also block air movement, greatly reducing the actual energy loss.

So when you're considering how much insulation to use and what type, remember that there's a lot more than the R-value printed on the paper facing. While it may be "acceptable" to the code officer for you to install R-30 fiberglass batts, wouldn't you rather use the r-value recommended by decades of research? Wouldn't you prefer a product that actually keeps insulating when it gets really cold or hot out? Once you close up the walls and ceiling, you're not going to want to change the insulation. So think carefully about it. Insulation isn't sexy but it affects your quality of life every day you're in your home.

This article was written by Ted Inoue of Energy Testing & Consulting LLC.

Ted Inoue
Energy Testing & Consulting llc.
New Hope, PA 18938
215-760-0211
www.etccreations.com