R-19 insulation for walls


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Old 07-20-14, 09:59 AM
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R-19 insulation for walls

In california, Title 24 is requiring all exterior walls to have R-19 insulation now. This is a major inconvenient code that occurred this month

Does anyone know how to achieve an R-19 wall without significantly increasing the wall thickness?
 
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Old 07-20-14, 10:04 AM
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What is the space available to you for insulation?
 
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Old 07-20-14, 10:29 AM
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I am planning to use 2x4 studs for the walls. So that means I only have 3.5 inches for insulation. Can a R-19 batt insulation be stuffed into it?

Also I hear spray-in foam is too costly which is why I am trying to think of another way. If it isnt costly and I can achieve R-19 with the spray-in foam into a 2x4 studs, let me know.
 
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Old 07-20-14, 05:09 PM
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Fiberglass batts can be had in 3 1/2" thickness that yield an r-value of 15. They are known as high density batts. You can install them in 2x4 walls and install a 3/4" polyiso. Foam board over the interior of the walls before the drywall or on the exterior before finish goes on.

Is this a large project or simply a few walls? You can buy DIY foam kits that will give you the ability to attain the required R -value if you are dealing with a small area. The cost of the kits is almost on a par with hiring a foam contractor to come in and do the job.

The other option is of course just to upgrade to 2x6 framing.

BTW, I might expect r-19 urethane foam to run in the $ 2.50 to $ 3.00 /sq.ft. range depending on job size.
 
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Old 07-20-14, 07:07 PM
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As Calvert mentioned, and assuming the walls will be constructed from scratch as new construction (not retrofit) a combination of wall insulation (such as 3.5" Roxul...R-15) followed by exterior foam sheathing (such as 3/4" Owens Corning Foamular... R-4) would satisfy the R-requirement.
 
 

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