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Old 10-23-2010, 02:10 PM   #1
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Insulating partial in-ground basement?


Hi all.. newbie here!! Great site

I have a raised ranch. My basement is less then 4' in ground. When we moved in, installed R13 batt insulation in the above ground framing. Then we framed because I was originally going to have someone spray in foam. Now I'm reconsidering. Plus our finances are real tight these days. I have about 12 sheets of 2" pink board insulation. My options are..

1. In order to install 2" correctly, I need to remove my metal stud framing. It's a lot of work, but at the same time, we plan on living in this house for a long time. Is it worth it?

2. Do I just leave the concrete alone essentially leaving an "air gap" insulating method?

3. Or leave the framing alone, return pink insulation and use towards someone coming in and spraying foam insulation?

Couple things...
* We live in NE IL and get a wide range of temps
* We have not had any water issues. Our house is up a bit on a hill and even when it rains like crazy and electricity out, we still don't have any water issues
* The basement is large.. apx 2,400 sq ft and some of it is living space/office space/kitchenette/storage
* We will be installing hydronic baseboard heat. It's what is in the rest of the house

Here is a pic of current condition..

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Old 10-23-2010, 04:13 PM   #2
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Insulating partial in-ground basement?


I am hoping you get some good replies because I have exactly the same question that you have.

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Old 10-23-2010, 10:30 PM   #3
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Insulating partial in-ground basement?


Welcome to the forum, to both of you! There should be no air gaps as this will negate the insulation with convective loops. Code requires fire-stopping every 10' horizontally and at the top of the inside wall to the floor joist spaces. Good that you have never had water problems because some of the "snap ties" used to form the concrete walls are still there. The new finished space needs egress (escape), one for the basement and one in each bedroom. SPF is great if affordable, I believe in the BSC way: http://www.buildingscience.com/docum...ent-insulation

http://www.aacounty.org/IP/Resources...ementGuide.pdf

I would add a sill sealer under the pressure treated (req. by Code) bottom plate for a thermal/capillary break. Add the studs directly against the 2" min. foam board with no vapor barriers or vinyl wallpaper on the inside to facilitate drying that way. Your location would be helpful.... Appears you may need a new window within the 44" AFF to pass Code unless a door is present. Did you foam under the concrete stem wall bottom plate or is that just alongside? I would add f.b. on there to prevent water wicking to the batt insulation: http://www.greenbuildingadvisor.com/...-building-code Any questions so far? lol. I will back the info with sites if needed...

Gary
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Old 10-25-2010, 12:05 PM   #4
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Insulating partial in-ground basement?


Joking I had to read it a couple of times to understand. It is the BSC article on basements that had me rethink the way we are finishing our space. Too bad I didn't read it before starting the framing a couple of years ago..

I have a couple other questions...

1. I installed a pressure treated 2x2 under my 1 5/8" metal studs. I glued and tapconed the PT to the concrete. Is it ok to keep this way?

2. Another option I have is to use the Pink Boards over my above ground framing and insulation. Then spray foam concrete up to it and above it on the rim joist.. in affect creating one solid foam insulating wall. Is this an option? When I asked my 2 architect friends about installing foam board over kraft faced, one said no issues, the other said to put some slits in the kraft paper.

3.
Quote:
Did you foam under the concrete stem wall bottom plate or is that just alongside? I would add f.b. on there to prevent water wicking to the batt insulation:
Did not understand completely? The old framing sits what looks like some fiberglass insulation on top of concrete. My new wall sits on a PT 2x2 that is glued n screwed.. no sill seal. If your talking about the foam under my window, it's just under the window because it was drafty..

INFO:
We live in Wauconda Illinois
Home was built in 1978 and the large addition in 2000
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Old 10-25-2010, 05:57 PM   #5
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Insulating partial in-ground basement?


2x2 on concrete under steel studs---- heard they rust, which makes sense because of the water vapor moving both ways. I think they would get the wettest from the outside vapor drying into the room. Without a thermal break, the studs warm to transfer heat to the plate and concrete slab, how much, I don't know.

Above grade foam board causes problems, as does the vapor retarder paper insulation next to it. I would use paper covered without the board above grade. http://www.buildingscience.com/docum...gs?full_view=1

Cover the top of the concrete stem wall with foam board (and seal), caulk/canned foam under the p.t. sill plate under the wood wall. The f.g. insulation will not air seal.

If you add more batt insulation above grade, move the paper v.r. out against the drywall. No air gaps between insulation, cause a convective loop.

Gary
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Old 10-25-2010, 10:04 PM   #6
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Insulating partial in-ground basement?


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Originally Posted by GBR in WA View Post
Cover the top of the concrete stem wall with foam board (and seal), caulk/canned foam under the p.t. sill plate under the wood wall. The f.g. insulation will not air seal.

Gary
Thanks Gary! I think I understand it. One question, as you stated above to put caulk/canned foam under the p.t. sill on the stem wall? How?? There is lot's of weight on it. Do you think I can use a pry bar to lift a little bit and caulk/can under?

Alex
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Old 10-25-2010, 11:03 PM   #7
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Insulating partial in-ground basement?


No, pretty impossible, unless a really, really strong bar. lol. Take a chisel or power tool and cut a sharp angle (1/4" high and wide) of the bottom edge of the sill out to replace with foam/caulking for an air seal. Air will move under the sill (unless on a sill sealer or two continuous beads of glue) due to the concrete irregularities. Also add a layer of foam board on the sill between each stud to prevent the batt from wicking any water in the sill. Standard p.t.wood is not waterproof, only treated for insect rot and decay: http://www.greenbuildingadvisor.com/...-building-code

I almost hate to show you this: http://www.steel.org/AM/Template.cfm...entDisplay.cfm

Gary

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