Framing a blanket insulated basement.


Old 12-31-05, 06:09 AM
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Framing a blanket insulated basement.

My family has just moved in to a 4 year old home (built in 2001) in Weld County, Colorado. Since my wife is pregnant, I'm planning on finishing the basement, so that I have a finished area to move my office area to.

Due to some soil expansion issues in the area, I've already done quite a bit of research on how to properly build the "floating walls" that code requires. It does not look too difficult, and seems well within my handy-man skillset.

What I am a little unsure about is what I need to do about insulation. Every guide and consult I've had in regards to wall framing indicates the best place to start is with 2x4 or 2x2 metal/wood framing against the concrete foundation.

My problem is that my basement was given corner to corner "blanket insulation", which covers every square inch of my basement walls (minus windows). It seems to have been run horizontally, and is held in place with a white plastic tarp-like wrap, with thick tape at about chair-rail level around the perimeter as well. In the corners of the basement, and about every 12 feet, there is a concrete nail that penetrates the wrap and the insulation and seems to hold everything in place up against the wall.

Should I remove this blanket insuation to properly frame my basement? (remembering that the frame actually is hanging due to building code, and can not get any static support from the floor)
... or should I frame inside it? (coming as close as possible without creating unnecessary stresses)
If I leave it up there, do I need to do any additional insulation?

Thank you in advance for any useful responses.
Old 12-31-05, 11:57 AM
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Framing a blanket insulated basement

You said it, since she is pregnant, you have to do something! You may as well remodel the basement. I know it will cut into your interior space, but since the insulation is already there, you could glue 2x4's to it with a top plate and bottom plate nailed to the above floor joists and glued to the concrete floor thereby creating a floating wall system. Now, you have to consider your window framing and door framing. It will be thick, really thick considering your 8" concrete wall, depth of the insulation, and the added 3 1/2" floating wall. Thats over a foot thick. Do you want that? If not, remove the insulation, build your wall, and replace the insulation, whether you cut down what is there or add R13 Your wall will be more solid if you do it that way, since you will be gluing the studs to the concrete wall. The combination of air space in the block and the insulation you add will give you a greatly insulated room. Don't forget to take into consideration electrical, HVAC, and any plumbing you may want.
Hope this wasn't too wordy.
Old 12-31-05, 12:20 PM
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After continuing my search for information on this, I've decided to just go ahead and build the walls inside the insulation. The 4" or so of space I lose along the perimeter of the basement is a fair trade off for me, considering it's a cost saver to not have to insulate it myself. Breaking down the insulation that is already there seems like it would be a lot of hastle... it was secured very aggressively.

The only place I will remove the insulation is in the stair well (because it sticks out farther then I could possibly put framing and drywall in comfortably), and possibly below the windows.

Also, I don't think I have to glue the framing to the insulation. Building inside the insulation, I am planning on building the walls like a partition wall, instead of relying on furring strips attatched to the concrete. Even though the walls are essentially hanging, they are still held in place to the floor with 60d nails, which they can slide on if my floor moves.

Diagram for a floating partition wall :

The deep window wells was something I didn't really think about. The basement windows face north-east and north-west respectively, which in Colorado means they get almost no sunlight. I suppose I will devise something creative to make it less of an eye sore.

No HVAC, no plumbing... I'm comfortable running electric.

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