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Insulation exterior block wall?

Old 04-15-2012, 07:45 AM
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Default Insulation exterior block wall?

The standard around here is 3/4" rigid insulation with 3/4" furring strip on top then drywall. That leaves a 3/4" air gap. Would the R-value be greater with the air gap or another layer of 3/4" insulation and no air gap?
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Old 04-15-2012, 08:12 AM
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Vermiculite
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Old 04-15-2012, 08:41 AM
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Originally Posted by 04keywest1720 View Post
The standard around here is 3/4" rigid insulation with 3/4" furring strip on top then drywall. That leaves a 3/4" air gap. Would the R-value be greater with the air gap or another layer of 3/4" insulation and no air gap?
I am not sure I am picturing this right but I would guess its better as required - adding material of any kind could increase conductive losses. A vacuum space for example is the best insulator. So I owuld say no. BUT if you do just make sure you do not also add a second vapor barrier.
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Old 04-15-2012, 01:07 PM
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Originally Posted by 04keywest1720 View Post
The standard around here is 3/4" rigid insulation with 3/4" furring strip on top then drywall. That leaves a 3/4" air gap. Would the R-value be greater with the air gap or another layer of 3/4" insulation and no air gap?
Fill the block cells with insulation, you can google that and find different types of materials that's if you haven't capped your block off yet.
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Old 04-15-2012, 06:25 PM
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Its existing block wall. So that option isn't going to work. Im just looking to see if the 3/4" airspace or an extra 3/4" of insulation is better. I'd assume the insulation is. The airspace gives and a 1 or 2 R Value and the 3/4" insulation is 5. Just not sure how important the airspace is.
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Old 04-15-2012, 06:32 PM
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http://www.energystar.gov/index.cfm?...vement_sealing
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Old 04-16-2012, 02:06 AM
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Z - Bar furring allows you to use 2 inch rigid then rock . There are no gaps between the sheets of rigid using Z .
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Old 04-16-2012, 03:09 AM
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closed or open cell spray foam?
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Old 04-16-2012, 07:31 AM
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We used 1" blue board, then 3/4" fur strips w/ 3/4" blue board in between. Reason was elect. boxes are 1 5/8" deep.
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Old 04-17-2012, 06:33 AM
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I've got an ICF house..2 1/2" foam on both sides of 6" poured concrete. Outstanding.

how about stripping with 2X (1 1/2") and solid foam? Even better.

Filling block is worthless..the heat is transferred through the webs of the block, not the dead air space.
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