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Ask the Experts!

30 July 2008

“I am investigating blown-in insulation for the front part (the oldest and coldest part) of my house. I have already installed wall insulation in the back part of my house when the walls were open. I am thinking of not putting insulation in the middle section of the house where all the bathrooms and kitchen are because of what I’ve heard/read about moisture problems when you can’t install moisture barriers. By putting insulation in sections like this, am I going to create “wind” patterns in my big old house where the air all moves to this un-insulated section? I’ve already put insulation in the attic.”

You will get convection currents in sections of the house where the walls are colder.  Cold air drops and warm air moves in to replace it.  I would not call them wind patterns, but there will be air flow.  I would recommend having a contractor dense pack cellulose insulation in the walls.  They can do this from the exterior by removing a row of siding and drilling holes through the sheathing or from the interior by drilling a hole in each stud cavity.  Unless you have high humidity levels in your home in the wintertime, condensation in the walls will not be a problem.

Answer provided by Paul Morin, Senior Building Analyst at the Center for Energy and Environment.

2 Comments leave one →
  1. George permalink
    7 January 2009 9:16 pm

    Hi- I am trying to insultate a room above my garage. It has a knee wall on both sides and behind the knee wall is open attic space leading to vented overhanegs on my home. the knee wall sare 2X6. Can I use R38 faced with tyvec behind the 2 x 6’s keeping the insulation in place + helping to block airflow into the room? Do you have a better way to insulte the knee walls?

    I am also doing the ceiling with faced R38 and unfaced R 19 on top of that. does this sound OK?

    • 14 January 2009 9:50 am

      Finding the best way to insulate your knee walls is going to depend on a number of factors, including whether or not the attic is finished, your access and the design. Here’s a link to the Minnesota Department of Commerce Office of Energy Security’s Home Energy Guide on Insulation. Kevin Brauer, our resident expert, is giving an adult ed class at Roosevelt High School in Minneapolis on February 24th from 6:30-8:30pm where he will be discussing the causes and solutions to ice dams, insulation and indoor air quality issues. The cost of the class is $6 and he suggested you bring a sketch or more information about your house/attic to that class and he can answer your more specific questions.

      I hope that helps! Let me know if you have any more questions.

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