Insulating a remodel

Discussion in 'Remodel Forum & Blog' started by Alex47, Sep 14, 2007.

  1. Alex47

    Alex47 New Member

    Sep 7, 2007
    I've got a 45 -50 yr old cinder block home, over a 3ft vented crawlspace in North Central Florida.

    1) The exterior block is not painted, though I may end up doing this.
    2) There are no moisture issues presently in the house (there was, but it was due to some grading issues that have been addressed), it's a dry house.
    3) The crawlspace has no vapor barrier down, though this may change, the floor is likewise not insulated (this also may change).

    The tear-out of the utility, mudroom, laundry area is about half done. I found the following about the old construction:

    1) The joists and subfloor are in very good condition and very clean, though there is about a 1 inch continuous gap between the end of the sub-floor, and the cinder block exterior can see down to the ground below.

    2) There was no insulation in the walls at all, I expected this, very typical of the time.

    3) The interior walls were made up of: furring strips under small (maybe 2'*3'-4') sheets of heavy drywall-like material, hung horizontally. The exterior side of this material was covered in an aluminum-type backing (I'm thinking this might have been an early type of vapor barrier, I can't figure they were thinking about radiant barriers back then). On top of the small drywall pieces was plaster.

    4) This all resulted in a small, vertically running air gap that runs from the crawlspace into the attic space.

    My questions are these:
    1) What can I do to insulate this when I re-construct?

    2)Am I O.K. sealing this entire airgap leading from the crawlspace on up? If I seal it too well, can I end up causing myself new problems (moisture)?

    3) Should I consider any type of vapor barrier, or should I just insulate and let it breath as it has.

    I've already got some thoughts, but would like as much input as I can get.
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    Well, you'll get lots of's mine. You need a vapor barrier on the ground of the crawlspace. You didn't have a problem since it is well ventilated. WHen you add insulation, you will be stopping that airflow. I'd consider a spray-in foam for insulation in the walls. This would also add a vapor barrier if it was a closed cell foam.
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  4. Alex47

    Alex47 New Member

    Sep 7, 2007
    I forgot to include that I've re-framed part of it with 6* to contain the new wet wall for the washer set up. This is the exterior wall.

    Of course nobody seems to be having any input........c'mon, I'm just looking for opinions!
  5. geniescience

    geniescience Homeowner

    Nov 27, 2005
    humid summers hot, humid winters cold
    yes this was a radiant barrier at that time; "they" did know about the physics of heat transfer at that time.

    My guess is that the gaps (both the gaps you described) were left by the builders as a way of being cautious. Like insurance. Now that you know the house is dry, you can be more certain. I would probably close off the continuous air gap in the wall. In order for a radiant barrier to work, it must touch air, not solid material. Use foam.

    About the floor, I have no clear idea what to do.

  6. Alex47

    Alex47 New Member

    Sep 7, 2007
    Thanks for your advice.

    Why the quotes around "they"? I just meant the standard of the day.

    I agree with you, I'd like to use foam. The room being only about 8.5 * 10, and just under half the wallspace being exterior wall, I thought I might have a hard time getting somebody out to spray. I guess I could add in the interior walls to muffle sound into the rest of the house, might not even really add to the price.

    I might look into one of those DIY foam kits, but they look a little expensive.
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