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Insulating behind existing wood siding


rockford33's Avatar
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Join Date: Aug 2003
Posts: 239
MD

10-12-07, 07:04 AM   #1  
Insulating behind existing wood siding

My parents have a 31-year old house with the wood siding and 1x2 batter strips nailed on. Looks like it is just 2x4 construction, with drywall, stud, and wood siding. They had an addition added a couple of years ago and when some of the existing walls were removed there was practically no insulation left. I have been trying to find a way to insulate the walls, but I found somewhere that if you had exterior wood siding, you needed an air gap behind the siding to allow moisture to wick away, or run down the interior of the siding and go out a small gap at the bottom. I had looked at the DIY slow rise foam, but it would be $$$$, and blowing in cellulose would create a lot of holes and lose any air gap behind the siding. My mom does want/can't afford new siding, so replacing it and re-insulating it isn't an option. Any ideas? I thought about pulling off a panel at a time, installing new FG, and putting the siding back on (or replacing as necessary), but it is a 2-story house. It wold be quite a chore, especially getting close to winter, and I am moving out of state in the spring,so I won't be around to do it then. I am going this weekend to pull off all of the exterior window trim and foam around the windows to seal some of the potential draft areas. I was hoping to get an energy audit on her house, but have had trouble finding a company in MD that does them (and will return my emails). The local energy company doesn't do them.

Any thoughts on getting some insulation in the walls?

Thanks,
Neil

 
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d00bs's Avatar
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10-12-07, 03:52 PM   #2  
I would blow in dense packed cellulose into the walls. If you make it dense enough you dont need an air gap.

 
KField's Avatar
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10-12-07, 05:17 PM   #3  
d00bs is correct and when cellulose is installed correctly it has a very good R value. The holes get plugged when the job is finished so there is no place for air to move. Perhaps if you find a cooperative contractor, you could remove a few siding panels and he could blow the insulation and plug the holes, and then you could reinstall the siding.

Go to http://www.comfortinstitute.org/member_locate.php and see if there is a contractor in your area. These people are well trained to determine where houses are losing energy. Also ask if they do thermal imaging. It can reveal some hidden flaws also.

Ken

 
rockford33's Avatar
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10-23-07, 05:55 AM   #4  
Well, the other weekend I was doing some weatherstripping around windows and doors at my mom's house for her. After pulling off some of the trim, I was able to pry the siding out just enough to see behind it. It looks like there is still insulation in the walls. It did not look as bad as I thought it would, although I was only able to look in very limited areas. One thing that did kind of concern me was how loose the siding was. It was attached to the house, but there are definitely a lot of air gaps around the siding that can let in the cold winter air. While I had some window and door trim off, I use caulk and foam sealant to close up as many of the air gaps that I could, plus nailed the siding onto the house a little better around the window and doors before putting the trim back on.

There is still one main problem that I can see, but I am not sure if it can be fixed. The house construction (from whatI could tell), was basically drywall, insulation, tar paper or something (not Tyvek), and then the 1/4" +/- wood siding. The paper appeared to be attached to the siding, not the house. The siding overlaps the concrete slab foundation (no basement), and I could literally put my hand up under the siding and feel the top of the slab and the insulation in the wall. This would seem to be a large air gap along the foundation that would let air into the house, and the FG insulation, from what I understand, isn't great at stopping air infiltration. I would like to seal the bottom of the siding to reduce the air infiltration, but I am concerned that I could create a moisture problem in the wall since the moisture would have no where to go. Any thoughts on how to seal this air gap without creating a worse problem down the road?

Sorry for the long post.

Thanks,
Neil

 
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