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  1. #11
    Join Date
    Aug 2007

    Default Re: Humidity from treated lumber

    Hi Flipper,
    OP is short for original poster (at least in my version of net abbreviations!). From your description it sounds like you are on the right track with the foam insulation. It may have been better to use it on the entire wall and not just between the flat 2x4's, I don't know if that will make a significant difference.

    I have attached a link discussing basement insulation systems. It covers vapor and air barriers, good and bad systems. There is other research there that will probably be helpful to review.

    You know your temperature and humidity conditions better than anyone else posting here, so you are the best judge of which strategy fits your scenario.

    Have Fun!

  2. #12
    Join Date
    Sep 2007
    Clayton, North Carolina

    Default Re: Humidity from treated lumber

    Thank you very much for al the good advise and suggestions. I think I am in good shape after all. I wll check the link.

    Take care and thans to all.


  3. #13
    Join Date
    Aug 2007
    The Great White North

    Default Re: Humidity from treated lumber

    Quote Originally Posted by Flipper View Post

    For insulation, I am using 1 thick extruded foam insulation from DOW. I have the PT 2x4s flat on their backs 16 on center and the foam is cut to fix snug in between. I did not glue the foam to the block hoping to leave a gap of air between the two were possible. This leaves me with gap between the foam and the drywall once installed.
    Flipper hopefully Im not too late responding with some feed back.

    I read the link provided by bp21901 and found it interesting they seem to hold the findings of John Timusk of the University of Toronto up here in Canada in high regards. Up here there is ongoing research and refinement to types of insulation and techniques.

    There should be absolutely no air space behind the insulation. Even the space behind studs should be filled with insulation. An air space in the back will cause an air loop that will pump water to the top of the wall creating condensation issues and could eventually cause rot in the floor joists as well.

    I would recommend with the materials you plan on using a modified method. Likely you can still salvage the materials that you currently have.

    The rigid panels of foam insulation should be secured directly to the foundation wall and continue up to the rim joist making sure it butts up to the underside of the sub floor above. When using an adhesive to secure these panels ensure using a continuous bead the entire perimeter of the panel and if adhesive is required in the middle ensure it is continuous from a perimeter bead to perimeter bead. This will ensure no air movement is possible behind the panels.

    At the seams where the panels butt together in the field use a tape thats used for house wrap applications this will seal those seams. One thing that we commonly do as well where the panels meet at the corners we leave about inch gap apply a bead of spray foam then butt the next panel thats 90 degrees to the previous and continue on from there. Also along the bottom of the panel and the floor we leave about inch gap which receives a bead of spray foam. Make sure to seal the edges of the foam panels along the rim joist either using spray foam or a good caulking.

    Then secure the nailing strips horizontally along the bottom and top with the field nailer's placed vertically directly on top of the foam panels.

    This will provide a continuous insulating barrier for the foundation wall and create the thermo break for the interior walls.

    Another perspective that hopefully helps.

    Further information check this link :

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