R Value Of Attic Spray Foaam

Closed cell spray foam has a far better r value per inch than other less effective insulations like cellulose fiberglass or even open cell foam.

R value of attic spray foaam.

When determining how much insulation you need don t guesstimate calculate. Since closed cell foam has a higher r value per inch installers generally spray 2 in walls and 3 in rooflines to meet the energy code requirements of r 13 and r 19 respectively. Closed cell spray foams are between 2 and 4 lbs. The r value of spray foam insulation is approximately 6 per inch so those using spray foam as their insulator will need about 6 3 inches of thickness to reach r 38.

Recommended insulation levels for retrofitting existing wood framed buildings. Wood has an r value of about one per inch of thickness. In comparison an inch of blown fiberglass insulation has an r value of 3 1 3 4 and an inch of blown cellulose in an attic has an r value of 3 2 3 7. Open cell spray foam typically has an r value of 3 5 per inch and it should be noted that open cell does not form a tight air seal.

As a benchmark one inch of solid wood has an r value of 1. All these have r values ranging from r 3 2 to r 3 8 per inch. It has a lower r value per inch than closed cell foam and is vapor permeable. Know exactly how much you need with our project calculators.

This is more common with closed cell foam but it happens with open cell foam too. Encapsulating the rafter or top truss chord roof framing members with spray foam will improve the energy efficiency of the attic space. The higher the r value the greater the insulation performance. The r value of closed cell foam is r 6 5.

Spray foam contracts and pulls away from framing. It performs much better than any form of batt for stopping air flow but it is not as complete of an air seal as closed cell spray foam. Two inches of closed cell foam will provide r12 r14 of insulation. Just like for open cell foam r values are additive.

They sport an r value of 6 0 8 0 per inch of insulation about double their open cell foam counterparts. This is because the effects of thermal bridging are limited which also results in the elimination of melt lines on the roof surface in cold climates. The r value of fiberglass insulation is approximately 2 2 per inch so much thicker fiberglass insulation is required to achieve the same r value of 38. How long does spray foam r value last.

R value is a measurement of thermal resistance and measures the ability of heat to transfer from one side of an object to another. Spray foam isn t thick enough. Closed cell spray foam insulation. Add insulation to attic.

Open cell spray foam absorbs and holds water. The r value is r 3 5 to r 3 6 per inch so filling a 2 4 cavity yields about an r 13. Open cell spray foam r values.