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Insulating refrigerated rooms

Lavrans Mathiesen | Posted in Energy Efficiency and Durability on

Ok, so the situation is a refrigerated interior room.

Location is the basement of a home in Portland, Oregon. Was advised on construction and insulation of the room already, but thought I’d like to find out if there is consensus among a broader array of people with experience.

Wine room with split system that cools and humidifies. Room is in the basement with one concrete wall and concrete floor. Frame in with 2×4 and add 3″ rigid insulation, foamed in place. Ceiling remains as existing with 2×10 joists and about 8″ of fiberglass insulation.

Greenboard on the interior walls of the wine room, standard sheetrock on the exterior walls. Walls primed and 2 coats of latex paint. Door with insulated glass panel and weatherstripping on all 4 sides.

Interior of the basement at about 68 degrees Fahrenheit, interior of wine room is 55 F, measured by liquid temperature. Humidity in the wine room should be around 65%, the average relative humidity for Portland year round averages about 69% by some accounts.

I’m wondering what details y’all would recommend in this situation. Not that there’s a problem, but it seemed like enough insulation, etc., but I’m wondering now (after the fact, of course) what would have been advised…

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  1. David Meiland | | #1

    Dewpoint calculator sez.... if you have 68F and 60%RH, condensation occurs at 54F. If that 60% rises to 65%, condensation occurs at 56F.

    Seems like air-sealing the "exterior" walls of the room is the crux of the biscuit. If the air in the basement cannot migrate thru the walls to the back of the greenboard, you oughta be good. Might have been a good place to use a layer of exterior foam with taped seams.

    I would have the customer buy you a handful of UEI dataloggers so you can monitor the situation for a year or two.

  2. Daniel Ernst | | #2
  3. Lavrans Mathiesen | | #3

    Well- what's the taped foam going to do at that point? If it's going to condense, it's going to condense on the wine room wall side as readily as the in-wall side of the rock, isn't it?

  4. Lavrans Mathiesen | | #4

    Daniel- that seems fairly close to the structure of the walls for the wine room, except for the studs providing bridging. There is a gap, and there should be an ability for vapor to move in both directions. Exterior walls are also painted with latex. I will be monitoring it.

    Although, the wine article was sort of funny, there are a couple amusing points about French wine... I believe it was 1870 that the California wines won 20 of the 39 medals given out at the Paris wine tasting, and it was just a few years after that when the French vinyards were attacked by a virus spread by aphids... a virus imported from America, and the American vines weren't affected by the virus. So they re-planted with American vines from California, which also led to the creation of hybrid grapes. So, in a sense, most French wines come either whole or in part from California grapes...

  5. David Meiland | | #5

    what's the taped foam going to do

    Assuming you used foil-faced you would have a very low perm layer, compared to the drywall, and one that's easy to make monolithic. If the foam in the stud bays is not meticulously sealed around all of the edges then there may be air pathways to the back of the interior wallboard.

    What do I know... I only drink cheap wine from Costco.

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