Finishing the basement

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Posted by: from Kirkland
3/27/2012 at 11:31:43 AM

My basement is totally unfinished. The contractor glued 2" white sterofoam from the ceiling 4' down. How do I insulate the concrete walls? Do I remove this sterofoam and put up studs and insulate with pink wool or do I leave the white sterofoam and stud in front of it and then insulate with pink wool.

The floor is concrete s with a 1" slope to the drain. Would it be better to build the subfloor with 2x3 on the flat side or use the 23"x23" barricade insulated subfloor?

Thanks for the info.


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Date/Time3/27/2012 at 5:34:33 PM

I would take the white foam off, I think it has an R value of 2. If you want a warm basement install the blue or pink foam insulation ( 1 or 2" thick ) and stud in front of that with Roxul insulation. That way you have a thermal break and the warmest possible wall, except for spray foam, which is a little bit expensive. Again if you want a warm floor, you can put down drainage board, 1 or 2" foam insulation and your plywood over that. If you want a perfectly flat floor you'll have to cut down 2x2 to lay on top of the drainage board or concrete ( depending on which system you go with), each one will have to be custom cut and will take some time to complete.

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Date/Time3/28/2012 at 12:33:16 AM

Hey Joe.

For me, i would just as soon leave the foam up, that is the coldest part of your basement wall. For the effort of removal and disposal I don't think its worth it. As James said, adding the blue or pink extruded foam board is the best way to seal the wall upm, that too can get pricey. I will usually start off by building my walls and put ty-vek on the back side. Keep the sud off of the concrete by 2" to allowing for the thermal break and to allow for some air circulation. The Ty-vek keeps the insulation in place and keeps it dry and is still breathable. Insulate with Roxul for the best bat insulation R value. I agree with James on the bulk roll of drainage board for your subfloor along with a layer of foam insulation and tongue and groove plywood. If price is of concern, you can do without the foam board without having too cool of a floor.

Hope this helps


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Date/Time4/1/2012 at 3:37:20 PM

Just a caution note here. If you leave the foam board on the wall, build a new stud wall in front and insulate with batt insulation you should not apply a vapour barrier on the room side.

Personally, the foam board on the concrete wall provides for an excellent thermo break and I would finish applying foam board to the balance of the wall. Be sure to spray foam the top and bottom parts of the foam board and tape all seams. I would then construct a stud wall with Blu Wood (be sure to place the bottom plate on a sill gasket) and insulate with Roxul (be sure to use the insulating type not the safe and sound type).

Also, do not forget to cut foam to fit in the rim joists space and tape all of the edges. Finally, given it is a basement, I would also use Blue drywall.


Kingsway Construction Inc

Glenn Rosborough

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