People often ask during their sauna build: “do I really need a floor drain?” Well, the best answer is always “yes.”
Why is a sauna floor drain a good idea for a proper sauna?
A proper sauna is one in which if:
- Someone wants to bathe in the sauna hot room, they can.
- Kids want to have a friendly water fight in the hot room, they can.
- The sauna owner wants to hose out or rinse out the hot room, they can.
Working up from the subfloor, we rip sleepers on our table saw, and glue and screw them down to our subfloor to create a pitch for the cement board. We create sleepers in a bicycle spoke arrangement like so:
We create a slight and gradual slope, so that when we glue and screw down durock, then skim coat it with vinyl cement, our floor is sealed and water will run to the drain.
A great way to ensure a solid floor is to run the sleepers in the bicycle spoke fashion, then, with a $10.00 bag of premium cement (no rocks) backfill the gaps between the sleepers with cement. Use the sleepers as a trowel guide to ensure a smooth finish. Run a wet sponge along the sleepers so that durock can lay flat.
The Trevor Trowel Method creates a really firm, well supported (and sloped!) base for our cement board.
Trevor also ran cement board up the wall, via his patented “sauce pan” method
I have built sauna floors every which way from Tuesday. I am a huge fan of vinyl cement repair. Check out this post on how to skim coat cement board for a “smooth clean finish.” As Trevor illustrates above, he has created a solid water tight floor that sheds water down to the drain. The floor is perfectly ready to accept a duck board overlay floor (gentle for bare feet and keeps feet dry) or even a “3rd step” for more vertically aligned hot rooms that get the sauna bather climbing up to an upper bench.
Slope Your Hot Room Floor with the “Ben Square” Sleeper Method, and Enjoy a Water Fight in Your Sauna Hot Room
Every once in a while, through sauna building user engagement, I am “wowed” with an enhancement to the sauna building methods detailed in my ebook.
User engagement with other sauna builders has allowed me to cross pollinate different ideas and methods. No ego, but with intent to help the next guy down the road. And just as with the Zen and Art of Motorcycle Maintenance, we have the author drawing parallels to understanding the mechanics of his motorcycle as empirical learning towards other aspects of life. I have enjoyed discussing different approaches to the nuances of sauna building with others as crazy as I am.
Because my eBook is in digital format (vs. printed), every once in a while we pick up on a better way to do an aspect of the sauna build. And thanks to the non patent process of copy & paste, I am able to share the enhancement with the next sauna builder coming down the pike.
With my ten or so sauna builds, I have always run 2x stock through my table saw to create sleepers on an angle through my table saw, sloping down to the drain, like so:
“Like any other engineer, I can’t help tinkering with a good design. Here is a picture of my floor slope method. I will put reinforcements at the Durock edges as well. Pieces are ripped in 1/8″ increments. Reinforcements for the edges of the Durock will also be added.”
- By adjusting our table saw to rip 2x stock in decreasing widths, we create a uniform slope to the drain. IMG: Glue and screw sleepers at decreasing widths to drain
- Cut Durock and mark sleeper locations. IMG: Marking sleeper locations on Durock
- Transfer marks onto Durock. IMG: Transferring sleeper locations with a T square
- Now this is a kick ass sloped floor glued and screwed and ready for the vinyl cement skim coat stage. IMG: A perfectly sloped and supported sauna hot room floor
A well built sauna hot room should be such that if kids want to have a hot room water fight, an adult need not have to say “Don’t do that!”
I’ve done it every which way ’til Tuesday. Rubber mats, Red Guard, etc. etc. But I like this method the best. The three “F’s” of skim coating:
- Frugal: $50 all in. Durock is relatively inexpensive, easy to cut and lay down. $8.00 – $9.00 for a 3’x5′ sheet. A bag of vinyl cement is well under $20.00
- Forgiving: Well mixed vinyl cement is easy to trowel and works its way into cracks and mistakes like nobody’s business
- Fast: All this takes about 20 minutes (and is actually kind of fun!)
SaunaTimes reader says: The SaunaTimes website has made me a converted man…I no longer want an outdoor sauna, now I NEED one! I live in Surrey, BC. Our winters are mild by Minnesota standards but the dampness and rain chill a person to the bone. I have started to acquire the materials to build my outdoor sauna and have a few questions about the ideal outdoor sauna design.
- The opposing bench design looks like a good idea on paper but I noticed your portable sauna has L-shape benches. Is there a change of “ideal”?
- Flooring in the sauna and changing area. Any recommendations on how to finish them or does bare plywood stand up alright?
I say: Wonderful email, and I’m glad to have helped and influenced you. You ask two great questions:
- “L” bench is the most ideal… yes, change to “ideal sauna” glad you caught it.
- Plywood floor. Yes, start with plywood as a subfloor, then:
Paint it or treat plywood with a water sealant. In the hot room, I suggest screwing in a drip edge around your perimeter. Your first row of t&g cedar can rest on that. I rip a 2×3 green to get a 45 degree upper edge. Cut and install a shower drain in the center of the hot room. Get a couple bags of vinyl cement patch, 40# I believe. It’s cheap. Mix that in a wheelbarrow. Trowel it down on the hot room floor. 3/4″ around the perimeter, down to about 1/4″ at the drain.
It’s a real slick system…. a couple points to keep in mind:
- Keep your bottom plate intact where your door is, or sawzall it and screw it down so your cement has a place to stop.
- Consider the patio block where your wood burning stove will sit. Lay that first, before cement. Trowel up to the patio block.
- Chalk line your drip edge before screwing it down to the bottom plate, framing, as a trowel mark, guide.
- You don’t need much of a pitch if your sauna building is level.
- You’ll build cedar decking (1×4 cedar with 1/2″ spacing) on top of this. This is where you’ll walk. Your feet stay dry.