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Blown-in insulation for small space?


RatLabGuy's Avatar
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12-29-10, 01:22 PM   #1  
Blown-in insulation for small space?

I have a walk-out bay area in the kitchen that overhangs the main foundation by a few feet, it's maybe 4' across and juts out 2' or so.
From the basement, I can access the space under it by leaning over the cinderblock foundation wall, between the joists, where the rim joist would normally be. It looks lihe there is poored concrete w/ rebar and a little gravel... some nut shells left from a rodent or two...

This space is pretty cold. and is keeping the kitchen floor above cold (no insulation between joists etc.
Before I seal off access to it when I finish this part of the basement, I'd liek to insulate that area better.
The problem is access is pretty limited, I can just peer over the cinder wall between the joists, the conrete layer is a frw inches lower than it on the other side.

Is there something I cen get to spray in? We're not talking about much total area volume, even if I pack up the joists. Like Good Stuff but alot bigger? a REALLY big can of it, lol
I wonder about moisture though, I assume there must be some w/ it being so close to the concrete/ground. The other option would be just packing in unfaced R30, but I wonder about it holding moisture, critters etc.

 
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RatLabGuy's Avatar
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12-16-11, 10:19 AM   #2  
Anybody?

I'm getting ready to finish that part of the basement and need to frame in the access space from underneath.

Would it be better to try a spray of some kind, or maybe just cut some XPS into cubes, and adhere it to the underside of the subfloor? E.g. try and "pack" the space w/ XPS?
Or just pack w/ fiberglass and move on...

 
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12-16-11, 10:36 AM   #3  
I'm not ignoring you, I just don't have a good suggestion. Obviously something needs to be insulated and to an extreme level since you will be closing that space off from any heat, what's best, I can't say. There is a product called Pearlite www.perlite.net that is used to fill concrete blocks.

Bud

 
condo-owner's Avatar
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12-17-11, 07:13 AM   #4  
you say its about 2' deep. and you can see/reach over the foundation ? how far ? if you can get your hand to about 1' from the farthest part. get some of the diy spray foam.

 
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12-17-11, 07:53 AM   #5  
Check out Foam it Green Spray Foam Insulation Kits

I haven't used their products yet but intend to.

Don't fill the whole void with foam, you will just be wasting your money. Spray the underside of the floor. Make sure the insulating you do in the basement somehow meets the insulation you do under the bay area. That way you don't have any by passes for the cold to get into your basement or up into your kitchen. Filling the void with cellulose sounds like it could be problematic. It iwll likely pick up moisture form being in contact with the ground/concrete.

 
RatLabGuy's Avatar
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12-17-11, 08:01 AM   #6  
From the underside it's probably more like 18". Yes I can get that close to the outer rim joist area.
You mean one of the small "kit" spray deals? How much coverage typically comes out of one?

There is a porch under the window with a poored pad (thats whats on the other side of the outcropping joists), so the area is functionally "enclosed" in but of course part of the problem is that gravel/concrete under there behind the wall is just on top of dirt so it's cold.

I'm assuming I should spray all the wood surfaces, including underside of the subfloor, to help w/ the warmth? How bad is the "spray back" from those things, since I'll be doing it into an enclosed space?
i figured once its sprayed, I'll cover the hole above the foundation wall w/ a 14.5" brick of XPS (like I've done around the rest of the rim joist spaces).

 
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12-17-11, 08:33 AM   #7  
OK thanks Drooplug, you replied while I was writing my response ;-)

 
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12-17-11, 08:58 AM   #8  
That website has videos of them using the product. So that should give you idea about blow back. I don't remember seeing any, but I'm sure it is possible if you get too close. They offer two types of tips, a narrow spray and a wide fan. They also sell different volumes. Be sure to get the closed cell version and go with a min of 2" thickness to create a vapor retarder. I think 3" would be ideal. Yea, spray it on the underside of the floor deck. I would bring it back over your block wall and then put your XPS in. The spray foam isn't going to be an even surface so plan on sealing the gaps between it and the XPS. Great Stuff will work if you are out of the other.

 
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