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  1. #1
    Join Date
    Mar 2014
    Posts
    1

    Question Need added insulation to 4" sidewalls.

    We have a 1975 prefab Wick home built in 1975. It only has 4" sidewalls and this winter was really cold and so where we. We have tried to add blown in foam insulation to the sidewalls. But when the contractor came out and drilled some test holes under the siding. He found that they are packed tight with fiberglass insulation.
    So we were wondering if added another layer of 1/2" drywall to the inside walls would make any difference in insulation value? Two years ago we did add a metal roof and had it insulated under the roofing as part of the home has not attic. That really made a difference in the summer with keeping the home cooler.
    This past winter will all the wind we will need to remove all the window casing and put foam insulation around all the windows. We had quite the breeze blowing in around the casings. Very frustrating.
    But now what to do to make the sidewalls warmer so to speak. Any help would be great.

  2. #2
    Join Date
    Jan 2014
    Location
    NH
    Posts
    136

    Default Re: Need added insulation to 4" sidewalls.

    Hi, Insolating around the doors and windows is a must but adding to the walls will not do the job. Your roof needs to be reframed to add an attic platform. This platform needs to be the full depth out over the walls and the roof attached on top of the attic platform not to the top of the walls. Thanks

  3. #3
    Join Date
    Jul 2010
    Location
    SoCal
    Posts
    6,598

    Default Re: Need added insulation to 4" sidewalls.

    Foam board insulation might help, 1/2" drywall won't.

    The previous suggestion about building an attic will help, but may or may not be practical, subject to your budget. If you do decide to frame a new roof, you'll most likely need a permit. Check with your bldg dept.

  4. #4
    Join Date
    Dec 2007
    Location
    Tennessee
    Posts
    1,747

    Default Re: Need added insulation to 4" sidewalls.

    How much money do you want to waste? If you add insulation over existing insulation, you will not get the results that you want. You need to pinpoint the exact points of heat loss and correct those. The best way to do this is with a thermal camera. Look for a service that will photograph your house showing you the places that are loosing the heat. In the long run, it will be a lot less expensive and work a lot better.

  5. #5
    Join Date
    Aug 2007
    Location
    Portland, Oregon, formerly of Chicago
    Posts
    1,794

    Default Re: Need added insulation to 4" sidewalls.

    The average american home loses more heat to leakage than to thermal loss. You will get bigger bang for your buck just tightening up all the leaks. This is especially true of older homes built before more attention was spent on air infiltration. Further, the averge home is only designed for average conditions, not the extremes that have been seen this winter. I remember Chicago having 28 degrees below zero with 40 mile per hour winds. Most Chicago homes are not built for those temps and winds!

    You don't state whether the house is built on a crawl space, basement or a slab. If a crawl space or basement, look for any hole or passage made for heating ducts, electrical conduits or plumbing. Many of these go straight up to the attic and out to the great outdoors. Every void in your ceiling made for such things as cannister lights, attic access panels, pull down stairs, etc. is a potential air leak. Where you have access to the attic, go up there with caulk or foam and seal everywhere pipes or electrical is coming up through the walls.

    Your house acts like a giant, oversized chimney. As air works its way up and out, outside air rushes in to take its place. You state that the windows leak air around the frames. That air would not be coming in if it did not have a way out!

    Normal furnaces rely on your house leaking like a sieve. It sucks and burns household air and sends the exhaust up the chimney.The furness blower creates a slight negative pressure in the home and air rushes through every crack to fill the void. When the time comes, replace it with a high efficiency furnace that does not suck air out of your house, but has its own outside air source.

  6. #6
    Join Date
    Mar 2014
    Location
    Midwest USA
    Posts
    3

    Default Re: Need added insulation to 4" sidewalls.

    What I did with my 1930 farmhouse with 4" walls full of blown-in insulation was I added another layer of insulation inside. Since the plaster walls were not in good shape anyway, I didn't care about the walls- I attached 2x2 vertical wood strips to the inside of the exterior walls over each stud using long deck screws, then filled that 2" cavity with Celotex insulation board, covered that all with sheet plastic, then screwed sheets of 1/2" CDX over that, and topped that with sheetrock.

    The reason I used plywood that way was so I could hang heavy sculptures and artifacts whereever I felt like and not be constrained by having to locate wall studs and install only over those.

    This method of course requires replacing or extending the window sills and soforth, but since I was planning to replace the windows and multi painted over cheap pine window trim anyway- it didn't make any difference.

    You would do well to add more insulation in the attic either additionally or instead of the walls, my attic had cellulose blown-in insulation there too, I bought a bunch of bales and got the machine and added enough depth up there to make it around R100.

    Probably the biggest difference was replacing the single pane windows with dual argon filled windows, and I saw an immediate measurable savings. For example, in my kitchen which was originally the back porch till about 1950, the old windows would ice over inside when it was very cold, as a result the room, which is where my desk is was always cold and drafty, that meant having to run a 1500 watt space heater on me.
    Soon as I replaced the 3 windows in the kitchen with dual pane windows I saw an immediate drop in my electric bill of about $35/mo because I was able to get rid of the electric space heater entirely.
    Before I was running it about 7 hours a day M-F and about 16 hours Sat and 16 on Sun.

    The way I figured it, every 4 months not using that heater pays for one window, it was a dramatic difference I could feel as well as see on my bill.
    I no longer feel the drafts caused by convection of the cold glass.

    I also had to have the heater in my bedroom at night on low, but replacing those two windows I no longer need the heater there either.

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