Open cell foam insulation values r3 r4.
Spray foam insulation r value 2x6.
In your case you have a total r value of about r 27 8 and 41 of 27 8 would be r 11 4 but in fact you have about r 13 of closed cell spray foam which is more than r 11 4 so you are good.
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.
After a ton of geeking out about wall assemblies including reading lots of articles and speaking with insulation experts builders and energy consultants my favorite assembly is nail base insulation zip r or atlas nail base on 2x4 or 2x6 framing with about 3 of spray foam.
Why spray foam insulation is so effective in meeting code requirements is that it has a higher r value per inch of product used than batts.
2x6 frame looking at interior insulation and thinking chris s argument for flash and batt.
This gives you great r value a continuous thermal envelope and.
In zone 5 at least 41 of the total r value of the roof assembly needs to come from impermeable layer of rigid foam.
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.
Considering diy blown fiberglass insulation vs spray foam both require care to get the thickness right.
Spray foam insulation vs fiberglass r value is about equal for open cell insulation and about double for closed cell insulation per one inch layer.
For 6 inches r 15 or r 19 etc.
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.
Spray foam kits are quicker and easier to use plus you get a seamless air barrier and high r value in just 1 inch.
For example closed cell spray foam depending on brand can offer an r 6 or r 7 per inch.
If the house is constructed with 2x6 studs the r value when insulating with open cell foam can reach a maximum of r 20.
If you want to install spray foam in a stud wall.
The r value of the high density spray foam wall decreases from an installed r value of r 30 to approximately r 20 a decrease of r 10 because of thermal bridging.
The low density spray foam wall decreases from an installed insulation r value of 21 to a whole wall r value of approximately r 16.
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R values are additive so you can multiple the number of inches of insulation thickness times the r value to arrive at a total insulation value.
Our open cell foam product has an r value of 3 5 per inch and in most applications a house constructed with 2x4 studs will have 3 5 inches of open cell foam thus resulting in a total r value of 12.
