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insulating un-insulated walls


havab's Avatar
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12-17-01, 03:57 AM   #1  
insulating un-insulated walls

I live in an old home and it appears that the walls in the house have no insulation.

I have heard that it is possible to insulate the walls by spraying insulation down from the attic. I'm assuming I would need to hire a contractor to do this. Does anyone have any idea on the cost of such a job? Any information (such as things to look out for) on this type of job is much appreciated. Thanks!

 
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12-17-01, 07:54 AM   #2  
The most common type of blown in insulation is cellulose. All that is, is munched up newspaper or similar product that is treated with boric acid. What the boric acid does is make the cellulose flame retardent. If you put a match up to cellulose, it will ignite. If you take away the match, it will go out.

Most wall insulating companies that use cellulose, use a technique known as dense packing. This is done primarily to get 100% coverage in the walls and to avoid settling of the product inside the wall. Some companies use thermal imaging to verify 100% coverage.

The type that you are referring to is a foam product that is sprayed into the walls. In new construction they mix the chemicals so that the foam expands within minutes of spraying and then they scrape away the excess. In old construction they mix the chemicals so that the foam expands slowly.

Both products are good, however, I prefer cellulose. They both are usually installed outside the home and what really counts if you have an experienced contractor doing the job. Always check with your local Better Business Bureau to see if the contractor you intend to do work on your home has any complaints against him.

 
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12-17-01, 11:21 AM   #3  
Insulman
I agree that in your situation cellulose is the way to go... Get at least 3 bids from different contractors in your area.. In this area of the country (S>E>Michigan) installed price by a reputable contractor would be approx $1.00 to $1.50 per square foot of insulated wall area...

If you have aluminum or vinyl siding be sure they don't drill through the siding and plug it from the exterior.. Sad to say but I have seen numerous homes in this area done that way.. A good contractor can remove the siding where he needs to drill to blow in the insulation..

Before you have any insulation blown in to the existing stud cavitys you should be 100% sure that there is no insulation whatsoever in the walls now.. Existing insulation in the walls will restrict the flow of the blown in cellulose, you will end up with huge voids that due not get filled.If there is any insulation in the walls at all, In my opinion it would be a total waste of money to try and add anymore.

Besides the insulation value the cellulose will provide, it will also help quiet down the sound transfer from the exterior to interior, as well as make your home more comfortable..

Good luck

Jim

 
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12-19-01, 04:49 AM   #4  
ohcowboy
Blow in insulation

I have a house built in 1925. The attic has plenty of insulation on the floor however there is no insulation in the walls. I do have acces to the wall cativity from the attic, where floor joist meet roof rafters. Has any one blown in insulation into wall cativities in this manner?

 
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12-19-01, 07:33 AM   #5  
ohcowboy

Yes, it is commonly done that way. However, you'll find out that not all you wall cavities will be accessable. A lot of times there will be fire stops placed, especially if the house has balloon construction. Actually if the walls are accessable that way, it's easier for the contractor.

 
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12-20-01, 01:23 AM   #6  
ohcowboy
blow in insulation

I have asked a few contractors regarding typs of insulation. Cellous,rockwool,cotton, and some type polystyrine foam. Most are saying that a foam pebble type would be the best. I am concerned with this house being a ballown style framing, regarding fire stops and possible moisture issues. what type of insulation would you suggest and what about fire stops?

Chris

 
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12-20-01, 05:55 AM   #7  
ohcowboy

I would recommend dense packed cellulose. There are basically two ways to prohibit heat from condensing in walls concerning insulation. One is to reduce the amount of humidity in the heat through the use of a properly placed vapor barrier and the other is to reduce the amount of air inside the insulation, which dense packing attempts to accomplish. You could further improve the dense packing by using a vapor barrier rated paint on the inside walls.

As far as the fire stops, the dense packing will provide that for you and cellulose is fire retardant because it is treated with boric acid. What that does for you is, if you put a match up to cellulose, it will ignite and if you take away the match, it will go out.

If you want to know more about insulation concerning vapor barriers, click on the little house icon with www next to it at the bottom of this message and read topic "Insulation".

 
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12-31-01, 07:01 AM   #8  
insulation

My husband and I are wanting to do this ourselves. Some of the do it yourself stores have the cellulose bags and if you buy so many you can rent the blower free. Is this something we can do from the inside or does it need to be done from the outside. We arent real comfortable taking up the siding. Any suggestions or tips?
Thanks-
Melanie

 
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