exterior insulation

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  #1  
Old 11-18-11, 11:09 AM
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exterior insulation

Hello,
I have a 1965 era ranch in northeast Ohio where it gets somewhat cold and windy, with limited insulation in the exterior walls. I think I have at best 2.0 or 2.5 inch batts in the walls. The master bedroom with three exposed walls is cold(one wall is 20' and two are 10'). It is over a crawlspace and has baseboard heaters.
I am thinking of adding insulation from the outside by taking the vinyl siding and celotex off, adding insulation and replacing the sheating and siding. I have talked to an insulation installer who told me due to the sagging of the old insulation they wont blow insulation int the walls from the outside.
Do I have a reasonable plan or will it be too cost prohibitive
 
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  #2  
Old 11-23-11, 07:40 AM
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I've been doing this to my home built between 1910-1920. I am on my last wall just about done. We had NO insulation between our studs in about 50% of the cavities since there really wasn't any insulation for large areas like wall cavities back in the day. The areas that did have insulation had been renovated in the past.

I used 3 inch polyisocyanurate boards that I cut slightly short and spray foamed in. I got much of the board for free on craigslist as to purchase it is quite expensive. BUT, if I had to buy it I would have as our home is only 2x4 balloon construction. 3 inches of polyiso is R-20 as apposed to R-13 fiberglass. This also made it nearly air tight.

Doing fiberglass would be good too and really not too expensive. Don't forget the federal tax credit is still an option this year if you didn't claim over $500 in energy efficiency stuff last year.

If you are going to rip off the siding you might as well cover the sheathing with foam board before you re-side for added R-value and a thermal break. We used 1.5 inch foil faced Thermax (more polyiso board) for an additional R-9.9. If you do do this you will have to re-trim the doors and windows as the wall will stick out farther.

This has made a HUUUUGGGGEEEEE difference in our home's comfort and heating bills and I highly recommend it. (I also added 2 layers of R-30 insulation to our attic for a total of 24 inches or R-73)

Mind you I was replacing the siding anyways so it made sense to insulate under the sheathing between the studs.
 
  #3  
Old 11-23-11, 08:19 AM
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What kind of insulation do you have in the floor from the crawlspace?
 
  #4  
Old 11-23-11, 01:14 PM
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I had R13 in the floor joist and nothing onthe crawl space walls and still had cold floors. I was told it may help to put the insulation on the crawl space walls and extend it 3-4 feet on the floor. So now only th walls are insulated and nothing in the floor joist.
 
  #5  
Old 11-23-11, 01:31 PM
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Is the crawlspace conditioned or ventilated to the outside?
 
  #6  
Old 11-23-11, 05:53 PM
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the crawl space has vents that I sealed with plywood and insulated over.it has a poured floor and is pretty dry, only a slight musty smell when really wet outside.
 
  #7  
Old 11-27-11, 07:46 PM
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Rigid foam (foil faced iso) is fine to the outside as long as you know that you don't have an interior vapor barrier.

You would be well served to seal up the bands on the crawl space and included some supply air.
 
  #8  
Old 11-28-11, 06:16 AM
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Crawl spaces need to be vented to the outside or conditioned, you've potentially created a problem by closing off those vents if this space is not open to the rest of the house.
 
  #9  
Old 11-28-11, 08:59 AM
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Ok. can I seal the bands with expandable foam?
So what is the best way to insulate the crawl, seal the vents, insulate the walls and leave it open to the finished basement somehow, or open the vents and insulate the floor joist and cover the access with a picture?
 
  #10  
Old 11-28-11, 09:27 AM
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Not finding it on quick glance but Bud posted a link to buildingscience.com in a thread recently which addressed how to insulate a crawl space.
 
  #11  
Old 11-28-11, 04:20 PM
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Even with 2 inches of sagging batts in the walls cellulose can be blown in. You need to use a wall hose that is slid up inside the wall and pulled out slowly as the bay fills. The air and material settings are a bit tricky but in general the air is all the way up and the material setting is very low. It takes a half dozen or so hole to get it right so you don't have hose clogs and it goes a bit slow but it can be done. For the crawl turn it into conditioned space
 
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