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  1. #11
    Join Date
    Aug 2007
    Location
    Maryland
    Posts
    1,580

    Default Re: Should we use spray foam insulation in a 130 year old house?

    HellNY, I think you have raised some very reasonable questions about your house.
    There isn't a wall made that doesn't allow water to get inside in some fashion. Nowadays we tend to limit how far the water can travel by using house wraps and solid sheathing. Even vinyl siding which is essentially waterproof will allow water to be blown under it, which then has to be drained off.
    Then we have to be concerned about trapping moisture either because of vapor being trapped in the wall or getting into the wall from outside.
    With the original uninsulated wall with no sheathing or even strapping any water that got in would dry eventually.
    I would be leery of placing foam directly against the siding too.
    Also placing fiberglass directly against to siding might allow the moisture to wick into the insulation.
    Any chance the studs are 2x6, then you could put in 3 1/2" fiberglass and keep it off the siding?
    Sorry, no real answer here.

  2. #12
    Join Date
    Mar 2011
    Posts
    1

    Default Re: Should we use spray foam insulation in a 130 year old house?

    I realize this post is old but I'm facing the same issues, and would like to continue for others benefit. HellNY, you seem to have done your research well. I actually work in the architectural field and there are many different thoughts on this issue. I feel confident that spray foam has a place in a propely designed wall system, however your 130 year old home was never intended to handle it, without more modifications that may or may not be possible. I have a 110 yr old home, plaster is still in good shape, but heating is outrageous. No insulation. So I've considered a slow rise closed cell foam for the wall cavities for its vapor barrier properties. But as has been said there is no guarantee that water won't find its way into our old walls, and then not have a good place to go/or dry out. I would not consider blowing in cellulose for the same moisture issues. Also the 'flash and batt' method is problematic as well for moisture issues. In my situation I ultimately decided to leave the wall cavities uninsulated. Focusing on the roof/attic area. Which for now, I'm blowing in cellulose under the attic floor. I may use a spray or rigid foam in the rafters some day.

    In considering doing spray foam in the rafters, I would not foam the underside of the sheathing but leave an airspace of atleast 1" preferably 2. I'd do this by using a furring strip (1x2) nailed up agains the backside of the roof sheathing and apply a surface (ie XPS insulation board, and either foaming to that, or continue layering xps) I've also seen people use insulation baffles for vented/vaulted ceilings, which are supposed to do the same thing, keep air moving behind the insulation. (like a 'Duravent' or 'Provent'. It may be an option for you with wall cavities open to install somehting like this against your sheathing/siding, and foam over it, allowing space for it to breathe. Then I'd foam the cavity full. I may also install a vapor barrior over the stud locations before putting back (drywall? or) plaster.

    my long 2 cents, a day late and dollar short.

  3. #13
    Join Date
    Mar 2009
    Posts
    1,387

    Default Re: Should we use spray foam insulation in a 130 year old house?

    Howdy consider reviewing these web sites i have learned so much from each.

    http://www.buildingscience.com

    http://www.greenbuildingadvisor.com/...vapor-barriers

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