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  1. #1
    Join Date
    Nov 2007
    Posts
    2

    Default How to insulate under stairs

    I am upfitting a studio apartment over a detached garage in Charlotte, NC. Lower level of the garage is not conditioned. I have installed R-19 (kraft face up) batt insulation between the joists. The wood frame stairs will have sheetrock attached to the underside of the stringers which will create a cavity of varying thickness. What is the best way to insulate this cavity? Should batt insulation be installed to the backside of the treads and risers- leaving an airspace of varying dimension between the sheetrock or should the insulation be installed parallel to the stringers leaving a varying airspace between the insulation and backside of the treads and risers? Any advice/ rationale would be appreciated. Thanks!

  2. #2
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: How to insulate under stairs

    To insulate the bottom of a staircase effectively and simply I would suggest to attach rigid foam sheets to the underside onto the stringers then cover with drywall.
    For 1 inch thick approx R4-5 and 2 inch thick R8-10 which should be adequate.

  3. #3
    Join Date
    Nov 2007
    Posts
    2

    Default Re: How to insulate under stairs

    So the unvented air space encapsulated on the warm side between the insulation and the stair treads/ risers will not be a problem?

  4. #4
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: How to insulate under stairs

    It really shouldn't be much of a problem since I doubt the stairs are that well sealed to begin with. The staircase is not likely in the direct heat zone of the living space itself unless there is a heat source along the staircase directly. I would be inclined to think this would simply assist with preventing cold infiltration up into the staircase

    If you like then an alternative would require to install insulation on the bottom of each tread and the back of each riser as well along the stringers .... the exception would be the bottom step since it would be difficult to get under the tread for that one.

    This is one suggestion.

  5. #5
    Join Date
    Jun 2007
    Location
    Erie, PA
    Posts
    51

    Default Re: How to insulate under stairs

    Look into Closed Cell Spray Foam Insulation, not only will this do the best job on insulating, but it will also glue all the stairs together and cut down on squeeks, creeks, etc.

  6. #6

    Default Re: How to insulate under stairs

    I recommend using PINK unfaced fiberglass insulation with drywall or Kraft-faced insulation with the facing toward the warm air if a vapor barrier is required. R-value will depend on the thickness you can install in the cavity between the stairs and the drywall.
    prior to joining the impulsive group Hidden Content gained operational and asset management experience

  7. #7

    Default Re: How to insulate under stairs

    If you live in Charlotte you should ask these guys they have many soultions in our climate area. I would use the pink stuff
    http://www.thefreshaircompanies.com/

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