Latest Discussions : HVAC


10:21PM | 12/26/04
Member Since: 12/26/04
1 lifetime posts
I live in a Chicago suburb in a beautiful all brick house built in 1960. I've recently discovered that the walls of my house have ABSOLUTELY NO INSULATION! Actual walls are as follows: exterior brick, cinder block, furring strips(no studs)...DRYWALL! The walls are cold to the touch in winter, and unbearable on those single-digit degree, 25mph wind days. What can I do? I've replaced drywall on one wall after doubling the furring strip and squeezing in batts of fiberglass insulation. Doesnt seem very effective. Is 3/4 of an inch enough space to "blow in" enough loose insulation to be effective. How expensive is this process? Please help a desprately cold single mom!


09:51AM | 12/27/04
Member Since: 06/23/04
161 lifetime posts
The 3/4" cavity isn't wide enough for blown-in insulation.

There are certain expanding foam insulations that are installed through holes drilled between each stud but this system is not very reliable. I have removed drywall from several such installations and found many large voids as well as foam that had shrunk 1/2" away from all the surfaces of the cavity. This system doesn't do much to alleviate infiltration (leaking air currents).

You have few other options but to repeat your last method or something similar. Keep in mind that if 3.5" insulation batts are flattened to 1.5", the R value will be less than half of their rated value. The R value is only accurate if the batts are able to fluff to their full thickness.

You might consider using 3/4" urethane insulation board. It comes in 4 x 8 sheets with an aluminum foil skin on each side. This board has a relatively high insulation value of about R-5, is very light at under 2 pounds per sheet, and is very easy to cut with a box cutter. Remove the existing drywall, fill the spaces between the studs with cut pieces of 3/4" insulation board.

Then apply a second layer of full sheets over the furring strips as you would drywall. Tape the joints with metal duct tape (not to be confused with regular cloth duct tape). This layer will add to the insulation value and it will stop most infiltration. Finally, install the gypsum board using extra-length drywall screws instead of nails. You also need to add "extension rings" to the electric outlets to bring the boxes flush with the new drywall line. The total insulation value will be about R-10.

To simplify matters, leave the existing drywall in place and follow only the preceeding paragraph.


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