Open Cell Spray Foam R Value 2x6 Wall

Builders and homeowners are often surprised to learn that there isn t much difference in whole wall r value between a stud wall insulated with open cell spray foam and closed cell spray foam.

Open cell spray foam r value 2x6 wall.

He does however pass code using the performance method as opposed to prescriptive. To understand why we need to start by discussing the trimmability of cured spray foam. As it can achieve 2x the r value of open cell inside a standard wall. A spray insulation is referred to open cell or closed cell because of the difference between the small bubbles.

This process must be completed before the drywall is installed but after the exterior sheathing and all of. Open cell spray foam insulation. Comparing blown spray foam insulation cost vs fiberglass including a comparison of insulation types r values and the cost of spray foam and fiberglass insulation. If you want to install spray foam in a stud wall and price is no object then it would seem to make sense to specify closed cell spray foam right.

Open cell spray foam has a low density which makes it vapor permeable. Michigan code in my area says wall assembly has to be r 20 and r 49 for the ceilings roof. This can t be done with closed cell foams but they require much less thickness to provide the same r value. Open cell spray foam has an r value of about r 3 7 per inch while closed cell spray foam has an r value that may be as high as r 6 5 per inch.

You ll find it used for ceilings walls and roofs. The builder in question typically uses a 2x4 open cell spray foam wall assembly of r 14 and r 60 for the ceilings roofs. Spray foam insulation comes in two types open cell and closed cell. A 3 in thick layer of open cell spray foam has a permeance grade of 16.

Another option is to use a foam in place technique with open cell polyurethane foam. Closed cell spray foam and open cell spray foam have very different r values per inch. But that s not their most important difference. Use 2 3 inches closed cell foam it green for 2 6 walls.

Open cell foam is relatively easy to cut which allows installers to fill the cavity passed the edge of the studs and to cut off the excess.