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Insulation in Crawl Spaces

| Posted in Energy, Heating & Insulation on December 19, 2004 09:13am

Should you insulate the stem wall or the floor joists? 

On our first house we insulated the stem wall, left the dirt floor bare, and left the ductwork uninsulated.  The crawl space seems semi-warm and totally dry.

On our second house the inspector forced us to insulate the floor and the ductwork.  The vents are all closed since it is cold here in Colorado.  The crawl space is damp with condensation on the vents and on the rim joists.

What is the correct way to insulate the crawl space in a cold, but relatively dry climate?  Would foam board on the outside of the stem wall improve condesation?  Would plastic on the ground help?  Foam blocks at the vents?

Thanks for helping.

Reply

Replies

  1. User avater
    rjw | Dec 19, 2004 02:54pm | #1

    This question is frequently discussed. Try a forum search.

    BTW, IMO the first is better, but with plastic on the floor.


    I don't know about yours, but my church isn't a hotel for the holy, it's a hospital for sinners


    Sojourners: Christians for Justice and Peace

  2. rez | Dec 19, 2004 05:08pm | #2

    Greetings CowCoy, as a first time poster Welcome to Breaktime.

    That question has been addressed here on Breaktime a number of different times in the past.

    If you scroll down in the lower left corner of your screen there is a search function that will take you to previous threads dealing with whatever you type in the search bar.

    If you type in 'crawl space insulation' or other keywords of the subject matter you'll get a good supply of data from those old threads.

    Cheers

     

    1. User avater
      IMERC | Dec 20, 2004 04:16am | #3

      upper left.....

      Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming

      WOW!!!   What a Ride!

      1. jimblodgett | Dec 20, 2004 06:03am | #4

        not if you're in Australia. 

        1. User avater
          IMERC | Dec 21, 2004 06:41pm | #9

          that's on the list..

          Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming

          WOW!!!   What a Ride!

      2. rez | Dec 20, 2004 08:46am | #5

        Fine. You go tell 'em then.

        Then you can explain the extra steps and then explain why it doesn't always work. 

        1. User avater
          IMERC | Dec 21, 2004 06:42pm | #10

          better odds on hits..

          Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming

          WOW!!!   What a Ride!

  3. dIrishInMe | Dec 20, 2004 06:33pm | #6

    Welcome to BT.

    Start by installing 6 mil poly on the floor.  Make the job as tight as possible, and maybe run the poly up the wall 6" or so.  Seal the joints in the poly with either spray foam or polyurethane construction adhesive.

    That will make a significant difference.
     

    Matt
    1. CowCoy | Dec 21, 2004 03:45am | #7

      What if the ground and stem walls are already wet?  Should I try to dry them out first or cover them wet?

      Thanks.

      Mike

      1. User avater
        RichBeckman | Dec 21, 2004 05:18am | #8

        "What if the ground and stem walls are already wet?  Should I try to dry them out first or cover them wet?"How wet is wet??If you have a lot of water, then you might want a drainage system to a sump pump.If the crawl is wet, have you checked the exterior of the house for water management? Does the ground slope away from the house? How far from the house do the downspouts get the water.?You can run a dehumidifier down there to dry it out, but it will only be wet again under the plastic after the work is done. Still, it might make doing the job a bit more pleasant.Rich BeckmanAnother day, another tool.

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