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Community and Q&A

Integrating a Home Sauna

Randy_Williams | Posted in Energy Efficiency and Durability on

I was in a home earlier this summer where the homeowner had decided to put a sauna on the second story of his home. The home was new construction with the homeowner acting as the general contractor, and is located in zone 7, less than 100 miles from the Canadian border, and is in a rural location with no inspections. Construction is code minimum 2 x 6 framing with osb sheathing, R-21 fiberglass bat and class 1 poly vapor barrier, house wrap and smart siding. No rain screen. The vented attic was not insulated when I was there, but will most likely be R-49 blown fiberglass. The sauna is 6 x 6 with 8 foot sidewall, has one exterior wall and the vented attic above with the poly vapor barrier. There was also a small vinyl non-operating window. He intends to add foil faced bubble wrap to the walls and ceiling and finish with cedar boards(lots of little holes punched in the vapor barrier). The sauna stove is electric. I did talk the homeowner into removing the recessed can from the ceiling and he added a wall light on an interior wall. I have no idea how often the sauna will be used. Given the 100% humidity level and a possibility of 150 degree temperature difference between outside and inside temperature while in use, what kind of problems would be expected and what should he have done differently?

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  1. GBA Editor
    Martin Holladay | | #1

    I'm guessing that everything will probably be OK (although the foil-faced bubble wrap may give off a funny odor -- not sure on that one).

    The worry with this room is outward vapor drive. The bubble wrap, believe it or not, should do a pretty good job of addressing outward vapor drive.

    Reducing air leakage is always a good idea, and it's not clear how much attention was devoted to air sealing. Getting rid of the recessed can light was obviously good advice.

    This type of sauna is probably used for only 6 hours per week or less, so I doubt there will be many problems.

  2. tundracycle | | #2

    Old thread but for others who stumble across it…

    - Sauna's do not get to 100% RH. Typically 30-40% is about the highest. However, that's @ maybe 200°f so still quite high moisture content.
    - Sauna temps are typically 170-220°f or more so can often be greater than 150°f diff, especially to outside.
    - Vinyl windows are not recommended as some vinyl can get soft and loose its integrity and all vinyl will off-gas at sauna temps.
    - Foil bubble is not recommended due to the high temps. It can work OK in some cases but not in others. Foil faced PISO or PIR is a better option.

    There's some more info here:

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