Thoughts on tile vs wood slats for a DIY sauna floor?

I went with a matte porcelain tile floor in my 6x8 build last summer and haven't looked back. I used a textured 12x12 tile from Daltile to prevent slipping when things get steamy. To deal with the cold feet issue before the Harvia heater relly cranks up, I built a couple of small removable cedar duckboard sections that sit right where your feet land. It’s the best of both worlds becuase I can pull them out to scrub the tile and keep the central drain clear of dust and wood fibers.

For the walls, I’m firmly in the horizontal camp. I used 1x4 Western Red Cedar and the aesthetic is much more calming than the vertical look. The key to making horizontal work without rot is the furring. I installed 3/4 inch vertical furring strips every 16 inches over the foil vapor barrier. This creates a chimney effect behind the boards, letting any condensation drain straight down to the tile. If you skip the air gap, you’re asking for trouble, but with it, the horizontal boards stay bone dry. It’s a bit more work during the framing stage, but the clean lines are worth the effort.

I actually regret the tile in my last cabin build. Even with a central drain, the grout lines eventually got gross from sweat and high humidity, and cleaning them was a nightmare compared to just hosing down a sloped concrete pad. I switched back to a full western red cedar duckboard system in my current 5x7 setup. It creates a much better thermal buffer. When that wood heats up, the whole atmosphere changes—the smell alone is half the expirience. Tile feels like a bathroom; wood feels like a sauna.

On the wall orientation, I really have to push back on the horizontal look. I did horizontal in my first DIY kit and the bottom grooves started showing signs of mold within three years because moisture just sits in those horizontal lips. For my current build, I used 1x4 vertical tongue and groove. It facilitates much better airflow behind the boards, expecially if you use 3/4-inch furring strips over the foil vapor barrier. It might look diferent, but your framing will stay dry and your cedar won't cup or rot over the long haul.

Have you ruled out the expansion issues with those long horizontal runs? I’m always a bit wary of horizontal cedar becasue if your moisture levels aren't perfectly managed, the boards tend to cup or bow way more visibly than vertical ones. Even with furring strips for drainage, you're still looking at alot of potential movement across the grain that might mess with your joints over time. Also, on the tile—have you considered the thermal mass? It takes significantly longer to heat up a tile floor compared to wood. If you're planning on shorter sessions, you might find yourself waiting an extra 20 minutes just so the air near the floor doesn't stay frigid.

I’m all for the horizontal boards—just looks way better. If you’re scared of the grout getting funky like that other guy mentioned, just use an epoxy grout. It’s a total bear to work with during the install, but it’s bulletproof and won't soak up any nasty sweat or moisture.

One thing I’d watch out for with tile is your bench legs. Don’t let ‘em sit flush on the floor or they’ll rot from the bottom up. I always use some stainless standoffs or adjustable feet to keep the cedar off the tile. Makes cleaning way easier too since you can just spray under there.

You shoud defintely check out Thermory thermally modified wood if you’re dead set on that horizontal look. Standard cedar moves too much, but Thermory is basicly bulletproof when it comes to moisture expansion. I’ve had it in a steam-heavy setup for two years and haven’t seen a single bow.

For the bench legs, just grab some Richelieu adjustable furniture glides. They keep the wood off the tile so it never sits in a puddle. It’s a cheap fix that saves your benches from rot without having to mess with the floor slope too much.

Quick update — I decided to stick with the horizontal cedar and just used extra furring strips for airflow. For the floor, I went with the textured tile but used epoxy grout like someone suggested to prevent the gross buildup. It’s the perfect middle ground! I also made some small duckboards for the walk-in area so my feet stay warm. Thanks for the help!