With the advent of Spray Polyurethane Foam (SPF), the importance of R-Value needs to be re-evaluated. For example:
. Just ¼ inch of closed-cell foam can stop 99% of heat loss by convection.
. Three inches of closed cell foam will prevent 95% of heat loss by conduction.
The same holds true for air-conditioned structures.
As The R-value is less standardized for SPF products than for fiberglass or mineral wool products, (it varies by manufacturer), here is a Guideline we think you may find helpful:
|
Spray Foam Insulation – Type |
R-Value Per Inch (Average) |
|
2 Lb. Closed Cell |
6.6 |
|
½ Lb. Open Cell |
3.6 |
|
1 Lb. Open Cell |
4.5 |
So, to revisit our question – True, a higher R-value is better, but in light of today’s superior insulation products, maybe the question should be: Do we need a different grading system for thermal performance? SPFs will create an air-tight seal for your home, and closed cell SPFs offer higher R-Values per inch than conventional insulating alternatives. This is something to consider when weighing your options for an energy-efficient, comfortable, and healthy building environment.
