Insulating concrete basement floor and walls


Old 11-08-01, 09:34 AM
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I apologize for the repetitive question; I have in fact looked back at quite a few of the other posts but still wished to post my situation.
I am looking for advice on whether my following plans are appropriate.
Background information:
Live in MA. House is roughly 40 years old. Redoing a basement room over to make it into a dedicated home theater room. The room is already in a semi habitable state (it had paneled walls and a vinyl floor already) but hasn't been used for anything other than basement storage for 20 years. The floor is vinyl over concrete. We have two small sump pumps in opposing corners of the foundation where basketball hoop sized holes were dug through the concrete when a flooding problem occurred 20 years ago. There have not been any flooding problems since (we keep a constant eye on the pumps during bad storms).
Last weekend I tore down the old paneling off the walls exposing the 7 foot tall concrete below grade foundation along two sides. The existing studs, nailed to the concrete, are still in good condition and don't show any signs of rotting. There was also a very thin carpet over the floor, which I also pulled, showing no signs of dampness or rotting. So it appears though the concrete foundation is pretty dry (with the exception of the two holes with the sump pumps during really bad rain).
I plan to build a two-inch floating floor over the existing vinyl/concrete floor as a precautionary measure in case water ever does creep up into the room from the sump pump holes. I will be carpeting the new raised floor. I will also be covering the concrete walls with drywall screwed to the existing studs (furring strips).
So, would the following be an acceptable way of insulating such a room?
1. FLOOR. I will completely cover the floor with a 4 to 6 mil vapor barrier plastic or roofing felt (are these the same thing?) overlapping the edges and securing the strips to one another with some kind of adhesive.
2. I will build the new floors frame placing 2x4s every 16inches OC.
3. I will then fit yet undetermined rigid, foam type insulation between each of the floor furrings.
4. I will place a second vapor barrier strip over each insulation strip.
5. I will finally screw 3/4 inch plywood on top to make the floor.

1. Since the studs are already nailed into the concrete foundation, I will only be able to cut and place strips of the vapor barrier between each stud directly against the concrete wall.
2. Apply the rigid insulation between each stud to fit snug between them.
3. Apply second layer of vapor barrier.
4. Hang drywall.

Whew.... does this sound like an acceptable manner for accomplishing the job to make the room comfortable to be inhabited? I understand you don't usually do two layers of vapor barrier so I guess my question would be, do I need to do a layer against the concrete itself then the insulation, then another layer of vapor barrier? The reason I ask is because from what I read the vapor barrier usually goes INTERIOR to the insulation. Would it hurt to do it my way or would it be more beneficial then doing it with just the single layer of vapor barrier interior to the insulation?
I apologize for the length of my post, I just wanted to make sure I included ALL potentially relevant information. I thank you in advance and greatly appreciate any advice.

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Old 11-08-01, 05:23 PM
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Greetings, Pugaboom


You'll find the product best suited for underlayment.

You can install the 2x4 either flat (recomended) or on edge.
Before you install the 2x4 lay a sheet of radiant barrier material on top of the underlayment. This will insulate your floor better than foam and you will not have to worry a bout mold/mildew problems. Same for the walls. Install two layers and you will have more insulation efficiency and you'll find the room more comfortable because your body will not radiating excessive body heat to the floor and walls.

Thank you for considering my opinion.
Old 11-11-01, 01:36 AM
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Thanks for the reply rbisys, I greatly appreciate the response and advice. However, as I am in a pressing need, I will be choosing something that is readily available at either Loews or Home Depot (Polyisocyanurate rigid foam or a polystyrene form). Thanks again, I am grateful for you taking the time to reply. See ya.

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