Insulating Basement Floors

Discussion in 'Remodel Forum & Blog' started by ttw4454, Dec 30, 2008.

  1. ttw4454

    ttw4454 New Member

    Jun 16, 2006
    I am planning on insulating the walls and floors of my basement. I will use Styrofoam on the walls with furring strips and then drywall. I also will use Styrofoam on the floors and plywood over that anchored with tapcons.

    The question I have is should I do the floor first or the walls? Just don't know if it matters. I do have a dry basement currently. I live in Michigan.

    Thanks for any advice.
  2. harleysilo

    harleysilo New Member

    May 26, 2006
    I would be hesitant to do that to a basement. I had to tear out that same work at my current home because somebody installed it because the basement was dry. Turned out it just hadn't rained that hard or for an extended period of days during the 5 years they lived there. One real long rain and I had water under the floor.

    I've since had a company waterproof the basement. I wouldn't hesitate to do this type of floor now after seeing the basement dry for 2 years.

    If you do it, I would lay a grid of PT 2x4s down to screw your plywood to, insulating between the spaces in the grid. Of course if you are just going to put down carpet it might not matter.
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  4. frenchie

    frenchie Jack of all trades

    Dec 30, 2006
    Brooklyn, NY and Fire Island, NY

    Easiest to do floors first - when building the walls, attaching the bottom track to ply is a lot easier than attaching to concrete.

    If you're worried about future flooding or condensation, want a little extra peace of mind, lay some furring down under the floor & behind the walls, create an air/drainage space.

    You could also screw your ply just into the furring - easier than tapcons to the concrete - and let the whole assembly "float".
  5. ttw4454

    ttw4454 New Member

    Jun 16, 2006
    Thanks Harleysilo and Frenchie for your replies. The basement (tore down original house and rebuilt on original basement) is approx 35 years old and has not been wet per the previous owner. I've had the house about 5 years now and can attest to that as well. We live on a hill and drain tiles are gravity fed to a lake. I actually used Drylock on the walls just to double up my protection. When you say you waterproofed your basement is this what was used or something else?

    Frenchie, I also had thought about having a floating floor as you mention but didn't know if that was common practice in these situations. The finish floors in the basement will be a mix of carpet and laminate (i.e. Pergo).

    On the walls I was just planning on 2" Styrofoam and 2x3 firring strips to attach to wall. This would give me some room to run wires for outlets. I don't know if I should glue the foam on in addition to using tapcons into the furring strips. The 2" will give me R-10 on the walls. I had someone spray the joist boxes/ends with P.U. spray foam.

    Thanks again for your replies.

  6. Barkri12

    Barkri12 New Member

    Jun 3, 2009
    Verify your basement floor does not have a legitimate water infiltration problem. If your concrete floor has any kind of standing water during the winter months, then insulating the floor is going to be a waste of money. The water will ruin the insulation and wood framing around it.
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    Tape a 2'x2' square of heavy plastic to the floor in several areas and let it sit for a few days. If there is no condensation under the plastic at the end, you have a good chance of things staying dry.

    There are floating floor systems in interlocking blocks designed for what you want to do. Also, Owens-Corning has a system. Might save some time, don't know about money. Worth looking into.
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