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Sauna Roof

Floki | Posted in General Questions on

Hi, I’ve built an outdoor sauna cabin and looking for advice on the roof assembly!

The sauna will have high humidity, heat and moisture inside. So it is important the roof can breathe to the outside of the vapor barrier in case any moisture gets through.
I have it constructed as follows (from inside to out):
T&G ceiling boards + 3/4 furring strips for airflow behind the boards + Aluminum foil vapor barrier + rockwool between studs + T&G roof boards.

I have ordered metal vicwest roof panels. I am thinking of putting some 1×2 strapping on top of the roof boards, just to create more airspace, and put the metal roof on top of that. Maybe but some vent holes through the wooden fascia boards into that airspace? I was looking at roof underlayments but I don’t want another vapor barrier. Would a vapor permeable underlayment help?

Any help is much appreciated. I am not an experienced builder in any sense, I just love building saunas. The Climate is cold ( southern Ontario, Canada), so ice buildup is probably a factor in the winter

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  1. Expert Member
    Michael Maines | | #1

    I would use a vapor-permeable, water proof, airtight roofing underlayment over the roof sheathing boards. Pro Clima Mento is one such product. Over that I would run 5/4 (aka full 1") boards vertically to provide air flow (required by code and a good idea in any case), cross-strap with 3/4" boards and install the roofing on the cross-strapping. Condensation will drip from the bottom of the roofing panels in some conditions so it's important that the underlayment is waterproof and detailed to drain safely.

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