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  1. #1
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    Oct 2008
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    Default Insulating lathe and plaster walls in brick house

    I have discovered that my house has no insulation in the walls. It was built in approx. 1930's. We live in Canada so no insulation is a major problem. I have lathe and plaster walls in good condition and want to insulate the walls without tearing out the lathe and plaster. Will drilling holes in the paster cause damage? Will the plaster be fixable and what proceedure does anyone suggest? What type of product should be blown in (the exterior walls are brick). I hope that someone has done this before and can offer some knowledge on the subject. Thanks Ridesally

  2. #2
    Join Date
    Aug 2007
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    Maryland
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    1,157

    Default Re: Insulating lathe and plaster walls in brick house

    Do you have a brick bearing wall with just furring and plaster. If so, their isn't much room for insulation. Maybe only 3/4". I wouldn't count on blowing anything in if that's all you have. If it's brick veneer on studs, then you may have something to work with.

  3. #3
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    Oct 2008
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    Default Re: Insulating lathe and plaster walls in brick house

    It is brick exterior with studded walls and then lathe and plaster. There is a cavity in the walls we can tell from looking in the electrical boxes. what do you think?

  4. #4
    Join Date
    Oct 2008
    Location
    MBoro, TN
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    2

    Default Re: Insulating lathe and plaster walls in brick house

    We just purchased a 1912 brick home w/ similar issues.
    We are using foam insulation. It's blwon in thru holes & fills in the crevices, like "great stuff".

  5. #5
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    Oct 2008
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    michigan
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    32

    Default Re: Insulating lathe and plaster walls in brick house

    injection foam is your answer.. all the work is done from the outside of the house, so no holes to be patched and no paint has to be matched. it goes in like shaving cream, fills every nook and crany. hardens in a few minutes giving you a r-18 in a 2x4 wall.

  6. #6
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    Oct 2008
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    1

    Default Re: Insulating lathe and plaster walls in brick house

    is it possible to use the foam insulation from the inside. for example, drill small holes near the baseboards and put the spray foam in and then patch the small holes in the drywall?

  7. #7
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    Oct 2008
    Location
    michigan
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    32

    Default Re: Insulating lathe and plaster walls in brick house

    Quote Originally Posted by minnesota View Post
    is it possible to use the foam insulation from the inside. for example, drill small holes near the baseboards and put the spray foam in and then patch the small holes in the drywall?

    you can, it is a messy process. injection foam displaces the air and you need at least two preferabally three 3/4 inch holes. it is a fast process and the more air out the lot less chance of "popping" drywall, plus you have to deal with patching and trying to match the paint color. when done from the out side in the motor joint you really have to look for the holes and the air space between the brick and exterior sheathing can be filled giving you a thermal break witch is most important, a "seamless" sheet of insulation.

  8. #8
    Join Date
    Aug 2007
    Location
    Maryland
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    Default Re: Insulating lathe and plaster walls in brick house

    Filling the air space with insulation is not recommended. While it may up the R value, it is likely to cause problems down the road. The air space is there to provide a way to keep moisture from getting to the wall.
    Why only small holes on the exterior and three 3/4 on the interior? I understand the mess factor inside, but it sounds like the mess factor is just hidden when done from the exterior with the mess bridging the air gap to cause problems later long after any warranty is up.

  9. #9
    Join Date
    May 2008
    Location
    Pacific Northwet
    Posts
    1,356

    Default Re: Insulating lathe and plaster walls in brick house

    If you house has knob & tube wiring (individual wires on insulators) you may not be permitted to insulate without rewiring. Some localities don't permit embedding K&T wiring in insulation. Check with your local building department or electrical inspector.

  10. #10
    Join Date
    Oct 2008
    Location
    michigan
    Posts
    32

    Default Re: Insulating lathe and plaster walls in brick house

    Tripolymer injection foam is 40% open cell. this lets any moisture drain or evaporate away.
    Tripolymer can be installed in 3/4" -3" holes. a bigger hole means more patch work. we use 3/4" holes in brick so there isn't a unsightly patch that every one can see. take a look at the Photo Gallery at Injectionfoam.com
    It is also ok to install into a house with knob and tube wiring. it is a good idea to turn off the main power for a few hours until the foam is dry, then it is fine. it has a very good fire rating. I have personaly cut one inch of foam and melted a penny with a propane torch on top of my hand several times, right after you take the flame away you can imediatly touch all around the melted penney, and hold it there for as long as you want...It is NOT hot.
    Electrical Conductivity Test #100-982 >20 mega-ohms (no conductance) Heat of Combustion ASTM D-240-73 6,435 btu per lb. Fire Hour Rating ASTM E-119 2 Hrs.

    look at Injectionfoam.com for more info

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