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  • Insulation

    Age old question, If I use Kraft faced insulation can I put a 6 mill poly vapor barrier over it?

    Now how can in a balloon framed 100 year old home be sealed well with Kraft facing?
    Too many gaps.

    Years ago we would slash the Kraft and then add the poly.

    I'm going to do it but have never heard of a problem with it.
    Cold climate here.

    Having more fun rehabbing this beast but in the end $$$$$.

  • #2
    Fibreglass insulation is the cheapest on the market. I went with blown in cellulose in the empty walls and attic of my 1952 bungalow. Better R-value, flame proof(I did test it!), mold resistant and bugs will stay away from it as it is treated with borax. I removed a strip of exterior vinyl and I drilled a 2" hole and with an electrical wire I would probe to drill my next hole. Where there was brick I drilled the drywall from inside and patched each hole afterwards.

    My second choice is Roxul and that's what I used to make a bedroom downstairs. Foam insulation around the foundation wall, 1" air gap and roxul bats on 16" center.

    I recouped all the cost of material in one winter alone by saving on heating oil.


    • #3
      There is a great deal of information out there on pro's and cons of adding vapor barriers in old buildings. Green building advisor is a great source of information, Oak Ridge National Laboratory, National Park Service has really good stuff. You don't want to trap moisture in the walls but I wouldn't have a clue how to do that up there. In the southwest where I live it not as critical.

      I decided to use Roxul on everything because it's naturally non combustible and is healthier that other alternatives. It's easy to cut with the right knife and doesn't lose its shape. It's unfaced but you can added whatever barrier you want. Because of the natural porosity of my homes construction I'm not going to add a vapor barrier.

      What at I am going to do is seal the crawl space, add a vapor barrier, insulate the perimeter foundation and seal off air gaps as best as possible. Pipe and wire penetration will get sealed to reduce prevent the movement of air.

      There are a number of "smart" vapor barriers out there that may interest you. They claim to let the wall "breathe" to help remove trapped moisture.

      One of the most useful sources of information was the National Park Service oddly enough. I suppose with so many old buildings to look after they had to get good at it.
      Recommended and Not Recommended treatments for adding insulation to a historic building.
      Last edited by Mightyservant; 09-27-2018, 11:35 PM.


      • #4
        This link may be of some interest to you, It was buried in my desktop. In the upper left corner you can scroll down to differerent briefs that address other issue including roofing, structural, seismic etc.
        Preservation Briefs provide guidance on preserving, rehabilitating, and restoring historic buildings.
        Last edited by Mightyservant; 10-06-2018, 01:02 PM.