Home>Discussions>INSULATION & HVAC>what do I get if I press R19 into small space?
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walenta
what do I get if I press R19 into small space?

I have 4-5 inch space which I want to fill with fiberglass batts
I can put R13 in which takes about 3.5 inch or I can put down R19, - howwver R19 is 6.5 inch deep, and I Know but pressing it into smaller space I loose on insulation capacity - ie less than R19 ..... If I press R19 into 4-5 inch space - how much R does it represent?
Does R19 presssed down to 3.5 inch like R13 batts, have a higher insulation value than R13 - or might I install R13 right away...

canuk
Re: what do I get if I press R19 into small space?
walenta wrote:

Does R19 presssed down to 3.5 inch like R13 batts, have a higher insulation value than R13 - or might I install R13 right away...

I highly doubt it'll have a higher R value. Fiberglass bats rely on the air space that exists between each glass fiber for its performance. When you compress the the bats you are eliminating the air air gap and having the glass fibers contact one another. Glass is a poor insulator by nature. For example if you have a glass of ice cold water in a warm room you will notice the glass is cold to the touch and condensation will form. If you were to take that glass and put into a larger glass container with an air gap separating the two there wouldn't be that issue. Just like a basic thermos ... a glass bottle inside another container separated by air.

In my opinion there would be no performance advantage using the R19 stuffed into a space for the R13.

ed21
Re: what do I get if I press R19 into small space?

What canuk said.
I don't know what the R value would be compressed, but it likely will be less than R-13 or the maufacturers would document the 5 1/2" insulation at the compressed value too.
I would add that it's probably a PIA to install that way & could effect the drywall.

walenta
Re: what do I get if I press R19 into small space?
ed21 wrote:

What canuk said.
I don't know what the R value would be compressed, but it likely will be less than R-13 or the maufacturers would document the 5 1/2" insulation at the compressed value too.
I would add that it's probably a PIA to install that way & could effect the drywall.

Sorry - what is PIA?

ed21
Re: what do I get if I press R19 into small space?

pain in arse

goldhiller
Re: what do I get if I press R19 into small space?

walenta,

http://www.google.com/search?hl=en&q=compressed+fiberglass+batts+r+value

I would likely choose a different type of insulation if I wanted to completely fill these stud bays without breaking the bank, such as blown high-density cellulose or BIBs (blown in blanket which amounts to short strands of FG)

(Actually.....I would choose a different type of insulation.... period.)

The ultimate would be blown foam, but it's pricey and depending upon where you live......pay-back might be measured in decades instead of years.

goldhiller
Re: what do I get if I press R19 into small space?

walenta,

http://www.google.com/search?hl=en&q=compressed+fiberglass+batts+r+value

I would likely choose a different type of insulation if I wanted to completely fill these stud bays without breaking the bank, such as blown high-density cellulose or BIBs (blown in blanket which amounts to short strands of FG)

(Actually.....I would choose a different type of insulation.... period.)

The ultimate would be blown foam, but it's pricey and cost-effectiveness depends upon where you live, etc. Pay-back might be measured in decades instead of years when installed in walls.

neilc
Re: what do I get if I press R19 into small space?

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