How to insulate existing finished walls?

A S Brown
by A S Brown

what is the most cost effective way to add insulation to finished walls without deconstructing them, the rooms on the outer portion of the house radiate heat in the summer and cold in the winter. Windows have been upgraded, but can still feel the infusion of the outside conditions. Thanks.

  7 answers
  • William William on Jan 20, 2019

    Personally I don't like expanding foam insulation in large quantities to fill walls. If not properly mixed at the nozzle or installed there may be off gasing of chemicals into the air that can last for years. There are many horror stories of improper mixers, bad installation, and walls being blown out


    https://www.doityourself.com/stry/3-options-for-insulating-existing-walls


    https://www.hometips.com/diy-how-to/blow-wall-insulation.html


    https://www.thespruce.com/best-ways-to-insulate-closed-walls-4105870

  • Rose Broadway Rose Broadway on Jan 20, 2019

    Whatever method you use, it's still a messy job. I remember when my Dad did this to our home years ago. Here are several ways so you can decide how you want to do it.


    https://www.youtube.com/results?search_query=insulate+outer+finished+walls


  • Heje Heje on Jan 20, 2019

    Blown in insulation is probably your best bet though it will require a hole at the top of each wall section between 2X4s.

  • Oliva Oliva on Jan 20, 2019

    How old is the house? If you have "fire breaks" in the walls, you'd need to make enough holes sufficient to place cellulose insulation in each "bay".

    If your home is so old it has brick on tile with balloon construction, there is nothing to stop the insulation between attic and basement level, because these houses were generally built before "fire breaks".

    If you have textured custom plaster walls, you won't want to make holes in the plaster unless you're sufficiently talented to recreate the textured patterns.

    Unless you can find an acceptable alternative, you may need to consider floor to ceiling insulated draperies, in 2.5 x the width of the windows.

    • Em Em on Jan 20, 2019

      How do the draperies insulate the walls?

  • Em Em on Jan 20, 2019

    Failing to properly insulate your home can send your energy bill sky high, but the best time to do it is before you finish the walls. When you're living in a home with exterior insulation that leaves something to be desired, your best option -- short of uncovering the walls -- is to blow insulation into them. The procedure involves making holes in the walls, either from inside or outside the house, but they are usually easy to hide. Because you don't have the opportunity to install a moisture barrier in a wall that is already covered, there is a chance that the insulation will get damp. The shouldn't create a mold problem if it has been properly treated, but it may make the insulation clump. Even if the insulation stays dry, it will probably settle as much as 20 percent in a year or two. Clumping and settling affect the insulation value and may lead to the need for more insulation, so if you have a contractor on the job, it's wise to get a guarantee.

  • Oliva Oliva on Jan 20, 2019

    The more folds and the heavier the fabric, the more cold air is stopped from entering the room. It's not foolproof, because you cannot drape every wall, but try one window, using this method, to determine if it would help you. It made a marked difference in a foyer and over a garage space, with wall insulation issues similar to yours.

    If the drapery wraps around the ends of the rod to seal off the wall space 4-6" to either side of window (wrapping to lay against the wall surface), and is hung floor to sealing, you'll be surprised at the reduction of cold air.

    Avoid thin cottons or open weave fabrics which will admit cold air.

    Thermally lined or blackout fabric lined draperies work best. The fabric is available at JoAnn fabric, if you can sew.