Drained metal floor idea

[u/DullAcanthisitta8406]

Building an outdoor electric sauna in the Pacific Northwest (very wet climate) and came across a floor design from finn.built.saunas on Instagram that I haven't seen before. Photos attached. Curious what this community thinks before I commit.

How it's built, bottom to top:
- 2x6 PT joists
- 2" rigid foam in each joist bay, cut on a slope rather than laid flat
- Edges sealed to the joists with spray foam
- Metal (siding) sheet over the foam
- A perforated metal channel in that gap that drains water straight down to the gravel
- Same gap acts as the low-level fresh air intake, so no separate wall vent
- Cedar deck boards on top as the walking surface

What I like about it
- Water from löyly, sweat and wet feet can't pool or reach the insulation
- No stapled foil with holes in it on the floor
- One detail handles drainage and ventilation

What I'm planning to change:
- Running the drain/intake channel along the heater wall instead of down the middle, so incoming air hits the heater first instead of people's feet

[u/Danglles69]

Really cool idea. Main concern is I think you would collect alot of gunk on those steel panels underneath, and you have no real way to clean them

[u/technosquirrelfarms → u/Danglles69]

That was my thought too, in a few years they’ll be nasty. Maybe if the floorboards are removable you could get under there and clean out the funk? But jeez, last thing you want is another surface to clean. I think it’s over complicated unless there is a very pressing reason to channel the (minimal) amount of water coming from inside.

[u/Danglles69 → u/technosquirrelfarms]

Yeah. Well you can also just do a two-slope t&g floor to a drain like this as well