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Insulating Older Home with 2x3 walls and no vapor-barrier

DIY_DOUG's Avatar
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09-18-05, 01:36 PM   #1  
Insulating Older Home with 2x3 walls and no vapor-barrier

Hello All,

I am renovating a small older cottage home (800 Sq/ft) in the Bay area of California. (Dry 9 months of the year, the other 3 months are nearly constant drizzle). The entire home is framed with 2x3s which measure 1 5/8 by 2 5/8. The only covering on the exterior side of the walls is 4" Teardrop shiplap siding. The finished interior side will have 7/16 or 15/32 OSB for shear-wall and 1/2" drywall. What can I put inside these walls for insulation that will not cause a moisture problem? Assume that moisture can get in through the old siding. If I put a moisture barrier on the inside of the walls, won't the insulation absorb moisture that gets in from the outside through the clapboards? I am almost considering not insulating the walls at all and letting them "breathe" so that moisture that finds it's way in also has a way out... The City may force me to insulate, however. I do plan on insulating the attic and have no issues there. Additionally, If I put bats that are made for 2x4 walls into my 2x3 walls, my R-value will go down. What should I do? I believe cellulose is out as that will just get damp, compress, and become worthless or even worse, hold moisture that will rot out my framing. Any help would be appreciated...


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resercon's Avatar

Join Date: Nov 2001
Posts: 1,873

09-24-05, 08:53 PM   #2  
First and foremost, you should check with your local building officials what is and is not acceptable for your area.

If allowed I would choose blown in cellulose (dense packing) in your situation. All cellulose products are treated with chemicals. Not just to make them flame retardent but to make them moisture and odor resistent, like borate and amonia sulfate to name a couple.

Dense packing is a method of application with cellulose that reduces the probability of settling and increases the R-value.

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