Poured Concrete Walls For House

Discussion in 'Homesteading Questions' started by SouthernThunder, Sep 26, 2006.

  1. SouthernThunder

    SouthernThunder Well-Known Member

    Messages:
    192
    Joined:
    Jun 2, 2004
    Location:
    OK
    It will cost less than $3000 to pour 8" thick concrete walls for a house I am building. I don't plan on using ICF's or SIP's simply because they cost too much and are too hard to get around here. What I want to do is form them up. (I already have a lot of forms) Put in some rebar and pour. Then I will finish the inside with furring stips, 4'X8'x1" polystyrene insulation sheets, and sheetrock. Does this sound like a reasonable building method?
     
  2. Chas in Me

    Chas in Me Well-Known Member

    Messages:
    519
    Joined:
    Jun 18, 2004
    Location:
    Around here someplace
    If you insulate the inside of a wall, frost will form on the outside. If the frost freezes deep enough, you may get a broken foundation. That's a big concern up here in the north. If it's not a concern where you are, your plan makes good sense. Remember, a heated basement is not a good place to store veggies.
    Chas
     

  3. coalroadcabin

    coalroadcabin Well-Known Member

    Messages:
    1,435
    Joined:
    Jun 15, 2004
    If you already have the forms and you are certain you can keep the walls plumb and square I'd say go for it. Make sure you are getting at least a 3000 psi concrete and do one continuous pour.

    We just had our basement walls poured, 10" thick by 9' tall w/ horizontal and verticle rebar. We didn't insulate the exterior because termites love to munch on insulation and we do have a termite problem in some parts of VA. We did not do this ourselves. The cost of the forms just wasn't worth it, plus we wanted someone who knew what they were doing to make sure everything was plumb, level and square.
     
  4. heather

    heather Well-Known Member

    Messages:
    3,780
    Joined:
    May 13, 2002
    Location:
    western PA
    go below your frost line
     
  5. gobug

    gobug Well-Known Member Supporter

    Messages:
    1,274
    Joined:
    Dec 9, 2003
    Location:
    Colorado
    If the cement is below ground level, the insulation needs to be on the outside. That is code in my county, but it has a lot to do with moisture and mold. If the insulation and vapor barrier are inside the basement then the cement wall will allow moisture to penetrate and create a mold home between the foam and the cement wall.

    Termites do not eat foam, however, they will easily go through it to get to the wood in the structure. Some foam makers add a small percentage of boric acid during the forming process and this prevents the termites from going through the foam. Some ants, like carpenter ants will make nests in the foam if it is thick enough. The foam on the underground outside surface must be carefully installed or it creates a habitat for many species of ants.

    Cement is only an R value of about 1 per inch or less, so whether it is above ground or not it will require insulation in your area. The more rebar used, the lower the R value. The best foam is only about R 7 per inch so if you want a warm house and low heating bills, a lot of insulation is required.

    Good luck. Please post your progress.
     
  6. Pick-Axe

    Pick-Axe Member

    Messages:
    10
    Joined:
    Feb 17, 2006
    Location:
    Minnesota
    I built my ICF house 4 years ago. I have a geothermal heat pump. My heating and cooling costs for a year is ~$520. OBTW, I live in northern Minnesota.

    Pick-Axe
     
  7. Westwood

    Westwood Well-Known Member

    Messages:
    1,082
    Joined:
    May 13, 2002
    Location:
    North Central Arkansas
    Yes, you have thermal mass, insulated on the outside. Ground temperature wicks up from beneath. Much easier to heat and cool, and the thermal mass acts as a flywheel for heating and cooling.
     
  8. ttryin

    ttryin Well-Known Member

    Messages:
    120
    Joined:
    Apr 10, 2005
    Hello,

    Blessings and great good fortune for your new home.

    Become informed about your soil, climate and drainage. Will moisture wick up from your basement or foundation into the walls of your house? Concrete basements are the dampest parts of some houses. Would a basement be damp in your location, in some seasons, and why would that change above ground at your location? Principles about condensation will make your home liveable or not. I just read about concrete being superabsorbent of moisture, even in winter. One place to begin educating yourself is buildingsciences.com



    T
     
  9. minnikin1

    minnikin1 Shepherd

    Messages:
    1,658
    Joined:
    Feb 3, 2003
    Location:
    Central NY
    Does this principle of insulating on the outside hold true for concrete block also, or does the space inside the block provide an adequate air gap?
     
  10. SouthernThunder

    SouthernThunder Well-Known Member

    Messages:
    192
    Joined:
    Jun 2, 2004
    Location:
    OK
    If at all possible I want to put the insulation on the inside so I do not have to spend money to finish the outside. (wanted to leave it bare concrete) The way I understand it, in my climate, all I realy need to insulate as far as the slab goes is the outside perimeter which is where most of the heat loss occurs.

    Mold is a different issue and I can't effectively run the vapor barrier from under the slab and up the walls. They do however, make elastic non-permeable sealers. Do you think I could minimize inside moisture by using a vapor barrier under the slab and sealer on the inside walls? If I left the outside unslead it would allow moisture to come and go as it pleases and not effect me inside.