Slope your hot room floor with the “Ben Square” sleeper method, and enjoy a water fight in your sauna hot room

Every once in awhile, through sauna building user engagement, I am “wow’ed” 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 of the nuances of sauna building with others as crazy as I am.

Because my ebook is in Google doc. format (vs. printed), ever once in awhile 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.

The Ben Square Sleeper Method is a better way to slope a hot room floor.

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:

A saunatimes exclusive: firing strips to pitch floor to drain. Prep for durarock and skim coat.

But let’s check out Ben’s sleeper method:

Welcome Ben:

“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 durarock edges as well. Pieces are ripped in 1/8″ increments. Reinforcements for the edges of the durarock will also be added.”

The Ben Square Sleeper Method is a better way to slope a hot room floor.

By adjusting our table saw to rip 2x stock in decreasing widths, we create a uniform slope to the drain.

Glue and screw sleepers at decreasing widths to drain


Then cut durarock and mark sleeper locations:

Marking sleeper locations on durarock


See how an ordained engineer uses a T square to transfer marks onto durarock?:

Transferring sleeper locations with a T square (note mason jar ice water on tile saw so Engineer maintains 38% hydration through process).

And an engineer doesn’t need to scratch his head to think about how to mark sleepers for small durarock cuts:

Holding durarock vertical to get sleepers marked

Now this is a kick ass sloped floor glued and screwed and ready for the vinyl cement skim coat stage:

A perfectly sloped and supported sauna hot room floor, glued, and screwed and ready for a skim coat water seal (vinyl cement repair: sauna building secret #7).

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!”


UPDATE: Feburary 2021:

Let’s check in with Mike from High Intensity Health. He has embraced the Ben Square Method, and here he is in action.

Mike applying the Ben Square method for his new sauna build hot room floor, sloped to drain
Mike’s cement board overlay in his sauna hot room

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24 thoughts on “Slope your hot room floor with the “Ben Square” sleeper method, and enjoy a water fight in your sauna hot room”

  1. I purchased your guide about 1 year ago, thank you! I was going to use think set on concrete board to create a slight slope for my tile floor. My concern/thoughts with this method would be a leak into the wood fir strips between the wood deck and the cement floor. Reaction or ideas?

    Thanks you

  2. Skim coat your concrete board w/ vinyl cement repair. Then duck board over that. This method has worked well for me for 10 or so sauna builds. Outside of a full slab pour, If there’s a better method, I’d like to know about it.

  3. FYI, I ended up adding additional strips in 1/16″ increments to keep the spacing under 3″. The floor ended up extremely stable. Thanks for writing this up Glenn!

  4. How do you prevent water from seeping into the subfloor at the edges where the dura rock meets the vertical wood wall?

  5. David. Good one. I can tell that you are thinking. That solution is one of the key tricks, and I have it detailed in my ebook. Basically, you rip a 2×6 green and run a 45 angle on it and screw it into bottom plate tight against sub floor. First course of T&G cedar rests on the drip edge, and durarock butts up against the drip edge. Then blue tape the drip edge and vinyl cement right up to the edge.

    You can pour water down the wall and it won’t get up in behind there.

  6. Hello Glenn, why not use cedar boards for the drip edge instead of the green weathershield boards? Thank you. Asaph

  7. i like the question, Asaph. You can use cedar 2x stock for drip edge. For some weird reason, i’m partial to treated (about the only place i’m partial to treated) and i think it may have to do with that spot where the durarock meets the drip edge. This is a potential “wet for awhile” spot. Cedar can handle it, but treated seams like it can take it better/more, if there’s extensive moisture. Good one, though. Your question got me thinkin!

  8. Glen
    This is my first sauna build after moving to the Rockies. I’m unclear whether the drip edge goes on top of the cement board or do the sleepers and the cement board butt up against the drip edge? Do you use silicon caulk around the drip edge? It seems like your Ebook says the drip edge goes on after the foil wrap and after sloping the floor with the sleepers and covering it with the cement board. Is this correct? Ben’s photos look like the cement board and the foil wrap meet. Are they covering the drip board or is it yet to be applied. Thanks in advance. Jim

  9. Jim: there are a couple ways to do this. My extended experience (yes, as detailed in my ebook) is this:
    1. Foil wrap your hot room, tape all seams and ends.
    2. Glue and crew in drip edge to bottom plate along hot room floor perimeter. This will lock and seal the foil, sandwiched against the wall bottom plates.
    3. Glue and screw down your sleepers. Run a course of sleepers tight against drip edge along perimeter of hot room floor (to prep for our durarock sloped floor).
    4. Glue and screw durarock to floor. Butt the durarock against drip edge along floor. Use factory edge of durarock as much as possible against the drip edge. Try to orientate your cut sides for butting against durarock, or shave the cut sides real smooth to help with a tight fit, that seam butted against your drip edge around the perimeter.
    5. Skim coat your floor, being sure to get some of that vinyl cement along the drip edge, sealing off that area.

    You can run a bead of silicon calk around the drip edge if you like. And this is good left brain thinking as this material has expansion capabilities, even more than vinyl cement.

    As we scratch our heads and think about this system, in the context of a water fight in your hot room:
    1. Water running down the walls, will meet the drip edge and run onto your floor, and find its way down the drain.
    2. Water poured on the floor, like a 5 gallon bucket spilled by a clumsy sauna guest, will rush against where the wall meets the floor and go nowhere but will turn around and find its way down the drain via your sloped floor.

    I advanced this system above as I started building my mobile saunas. Theory being that a sauna bouncing down the road, the hot room walls may want to move around a bit, opening up these corners. The drip edge creates a transition from wall to floor, ensuring those seams are sealed well, and permanently.

    And to get more geeky, anytime we have a transition from one medium to another, in this case stone (durarock) to wood (cedar), we have a seam that is vulnerable to opening up. Different mediums expand and contract differently. So, A job is the right job here.

  10. This is an interesting system. We have pretty low, damp ground at our camp (near the shore of Lake Michigan in MI’s UP) and would like to build a sauna. I think a slab might crack unless we messed around with a lot of fill… I’ve also thought about putting it on posts to keep it stable in the freeze/thaw over the year. Would either of those be necessary, though? Would a mobile sauna with this type of sleeper system floor be stable enough to be set down in this kind of location?
    I LOVE this site, by the way!

  11. Hi Mary: Glad you are enjoying Saunatimes! There three options to support your sauna structure:, 1) slab on grade, 2) pillars, 3) float. These are in order of most elaborate to easiest. And you point out the pros/cons, below, For many sauna structures, #3 is the ideal choice. Especially if the structure is not too big. An 8×12 can float very effectively, even in the worst soil conditions. Wet clay areas can freeze unevenly and move a structure like a boat on Lake Superior in November. But with a small structure, it ain’t no big thing, as we can easily shim and level block as things may move, and often the points of contact move at the same amounts.

    Anyhow, a mobile sauna liberates oneself from all these shenanigans. We roll up and level, and in the case of using an ice fish house chassis, we can re-level as needed. And get this: instead of a sloped floor to drain, we can control the slope the entire structure. So, we can put in a couple drains, in each corner, and pitch our mobile sauna ever so slightly to one corner. Nobody will know the difference, but the water on thes floor will.

  12. Could you use ‘Z flashing for the transition from foil to durarock? Same idea as the 45 degree board yes?

  13. Yes, Mary. For sure. I like the 2x stock for drip edge concept as it gives us some dimension, some thickness for the durarock floor as transition.

  14. Glenn,
    Do you have a picture of of drip edge method? I’m still not quite sure how it’s done. They say a picture is worth a thousand words. 🙂 Thank you Glenn.

  15. Hello Glenn, I see that you fill the void between sleepers with cement while using the spoke method. Am I correct in thinking that you do not need to do the same when using the square sleeper method? If so, I assume that the cement board is strong enough to span the spaces between sleepers? Also, I see reference to glue and screw. I know that the sleepers are glued and screwed to the subfloor, but are you using adhesive between the duroc and sleepers also? Thanks for all the great info!

  16. Great questions Kevin:
    1. filling the sleeper void: You can do this. Otherwise, the durarock is strong enough to span about 4″ or so between sleepers. Lately, we have been filling the void. A 80# bag of mortar mix goes a long way. If filling the void, it’s important to dry fit the durarock first, and then when laying it down for good, after filling the void and troweling, be careful when screwing it down. Maybe stand on a 3/4″ remanent piece of plywood so your weight is carried across many sleepers.

    Oh, an advantage of the bicycle spoke method is that you can use some blue tape on the drip edge tto mark where your sleepers run.

    2. glue and screw. If filling the void, chances are the tops of the sleepers will be yucky and cementy from over pour and troweling, which is actually better than under pouring and under troweling. In this case, forget the glue and just screw down the durarock.

    Glad you’re rockin’ Kevin!

  17. Hi Glenn,

    I am in the process of a sauna build in northern BC. Wondering your thoughts on a plywood sandwich floor? The foundation is on a deck of 2×8 treated joists. I am thinking:

    – 3/4″ Ply on the joists
    – Sleepers in Ben Square method with 1″ as the smallest height
    – 1″ XPS Insulation between sleepers
    – 5/8 Ply on sleepers
    – Waterproof the ply with a product like Mapelstic
    – Duckboard on top

    This gets rid of the vinyl patch and the durarock. My concern with the vinyl patch is cracking due to movement of the subfloor – have you seen this at all? What about an uncoupling membrane between the ply and the vinyl patch such as shluter ditra matting?



  18. Hi Mitch,

    You can do this and i’m thinking all will be fine. I’ve not had any vinyl patch cracking in many years of doing this method.

    One thing you could think about is some Great Stuff! squirts between the Ben Squares, then lay down the durarock or plywood. Adds support there and a clever use of that product. Friends have done this to help support the floor and de sponge ify and it’s been very successful.

    I’m not up to speed on shluter ditra matting, and I may fire up the Googlator to learn more. It sounds like a cool name for an art movement or Mosiac IPA from Northern BC.

  19. Glenn!

    Have the eBook, refer to and this site daily–stove is in, on pavers, durarock behind w/ mortar, chimney is drafting and room is wrapped. (it’s been fun working in the cold with small test fires, now.)

    Anyhow, I’ve read-and re-read this post a few times and just want to say thanks for including this and the pictures.

    Will be doing this sleeper method tomorrow.

    Couldn’t have built it without your book and site.

    Thanks again

  20. Glenn,
    I am about to start the sleepers and floor and have been debating about filling the voids with mortar and just read your post above about using Great Stuff and I am intrigued. Hoping that its a bit simpler than the mortar! Just wondering if you just lay one “line” between the sleepers and then lay in your pre-fit cement board glue and screw and let that sort of sandwich the great stuff for somewhat of a fill of that void? As always your ebook and this site have been an enormous help!

  21. fab, Greg.. glad the book has been so helpful.

    This Great Stuff! business between sub floor and cement board, and between sleepers, is a Great Thing!.. And they may just package the same stuff in the same can and call it Great Thing! because it seems as if it were made for this application. It cures and becomes strong, helping support the space between sleepers. Just don’t walk on the cement board after you lay it down and the Great Thing!/Stuff! is wet.

    This is super hard to do, so some guys screw it all down, then come back and drill a hole in the cement board and give a squirt of the Stuff! in there.

    More of a squirt circle of a shot of it, vs. running a line of it.

  22. Glenn,
    Getting close, about to lay Durarock but wanted to ask which side you prefer to face up? The rough (mortar) side or the smooth (mastic) side?

  23. Greg:

    I’ve had better results with the rough, mortar side up. The vinyl cement glides wonderfully along with a trowel, creating an egg shell thin, perfect covering.

  24. Glenn,


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