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  1. #1
    Join Date
    Feb 2011

    Default insulating exterior walls

    I have an addition that has cold walls. I was wondering if its possible to remove the siding and add styrofoam and then replace the siding.

    Is there a specific styrofoam I should use?

  2. #2
    Join Date
    Mar 2009

    Default Re: insulating exterior walls

    Howdy how thick are the walls and what type of insulation in them? Did you add heat wto the space when you made the addition?
    If you have cellulose in the walls do not add foam to the exterior as you might cause mold and rot to the framing. The cellulose needs to be able to dry out allowing moisture to move threw the wall. If fiberglass you can add 4 by 8" sheets of Styrofoam which
    is easily broken or extruded blue or pink foam that does not . A consideration is whcih gives you higher R value for the cost of either. The foam helps reduce thermal bridging of the framing , making the walls loose less heat. 2" thick is the common thickness for retrofitting. Another consideration is you will need to extend any window or door jambs to reside the walls.
    If you have a basement or crawlspace is the rimjoist insulated? this is the outsdie wall board that the floor joists are attached to. Un insulated allows allot of heat transfer. insulating these cavities might be a great first step....

  3. #3
    Join Date
    Mar 2008
    nova scotia, canada

    Default Re: insulating exterior walls

    another thing not mentioned is that if 2" foam is used the overall length of the wall will now be 4" longer which means youll have to buy some new siding to be able to reuse some of the old.

    i do alot of large renos where we foam the outside of the house before the siding goes back on. however we use completely new siding across the entire house unless the existing siding is less than 4 years old. reason being matching it for profile and color it does fade
    fire up the saw and make some dust

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