What size sauna building is best?

As we consider the “empty canvas” in our backyard, most often, the first place to start when deciding what kind of sauna set up for your own backyard sauna is to define your sauna building size.

To help define and carve out the footprint for your own backyard sauna, all you need is some carpenter string and four sticks. Mark off your area.

As we begin to look at the location for your own backyard sauna, it’s easy to pound in stakes to define the footprint of what will become the footprint for our sauna building.

What size for sauna building?

Generally speaking, when considering the size for our outdoor sauna building, most fall into one of two camps:

  1. A somewhat urban or suburban backyard
  2. A more rural setting
In either scenario, it is good building practice to consider optimizing your sauna building dimensions in terms of minimizing the needed materials, as well as maximizing its usable space, and practicality. For example:

Backyard sauna dimension options:

  • 10’x10′ = 100 sf. = 40 lf. = 2.5 ratio of square feet to lineal feet.
  • 8’x12′ = 96 sf. = 40 lf. = 2.4 ratio of square feet to lineal feet <– The sweet spot!
  • 6’x16′ = 96 sf. = 64 lf. = 1.5 ratio of square feet to lineal feet.
  • 1’x96′ = 96 sf. = 96 lf. = 1.0 ratio of square feet to lineal feet.

We are smart enough to know that a 1’x96′ sauna building is completely absurd, But it helps prove the point that a building’s dimensions can have a big effect on its square foot efficiency. 10’x10′ is very efficient, but do we really want a 10′ long hot room?

An 8’x12′ sauna building is our most practical dimension for a somewhat urban or suburban backyard.

Brian Peterson marking off his territory outside his 8’x12′ backyard sauna

I’ll write more soon. I will build out the grid for a more rural setting footprint analysis and then settle on how a 12’x16′ is the sweet spot. But for now, you get the idea. This post is in development mode. I just finished 4 rounds on lake vermilion, had some dinner and going to geek out on some Netflix. It’s windy and fresh outside. This long hot summer is waning. It’s a bit early for a season change, but the nip in the air reminds me of:

25 thoughts on “What size sauna building is best?”

  1. We got the pad, the 8×12 shed is built. Now we’re trying to decide what kind of stove. We have gone back and forth. I think we are settled on a wood stove. Is there any type of clearance regulations around the chimney? Our neighbors branch is pretty close to the roof. Can’t wait to get going on the next phase!

  2. Hi Deb:

    Each area has their own rules and regulations for clearances outside, around a chimney. I suggest contacting a local fireplace dealer who should be able to talk local with you. I could plug the Kuuma here, and well, I’ll just say that a quality clean burning sauna stove developed with safety and efficiency in mind will produce a “controlled burn” such that the chance of sparks flying up the chimney is greatly reduced. Sauna on Deb!

  3. I have a 3x2m insulated cabin (couldn’t be any larger in our tight urban garden) with double doors on the long front side that serves both as home office and sauna.

    My solution to best utilize space was to spit the cabin diagonally, creating two triangles, giving both the office and sauna a narrow and a wide end.

    The diagonal wall creating the split has both the sauna door and the sauna oven on it, as well as two vents, one below the oven for cool fresh air to enter (the double doors to the outside are kept slightly ajar with a little chain) and one up high for hot air to exit.

  4. Hi, Glenn,

    Greetings from New Hampshire. First, thank you for your enduring enthusiasm and tireless dedication sharing information. Your DIY book was most useful for us in building our sauna. We have especially been grateful for your endorsement of the Kuuma stove. Daryl was really helpful when I contacted him and purchased one of his stoves.

    I am writing to see if you would be interested in a blog post on our process (and product!). Actually, on our family blog, I have written a three-part series of posts on our process that you can access and read here: http://farfieldfamily.org/tag/sauna/

    Perhaps there is something worthwhile in these posts for others? If so, I would be happy to write a blog post that combines parts of these pieces for your blog, if you are interested.

    Again, thank you! Mark

  5. Hi Mark,

    Thanks for the kind words and chiming in. For sure we can visit with the guest post. A lovely sauna built with great attention to detail and quality and love. Hashtag: kindred spirit!

  6. There are a few concepts/designs within the book. Mainly we dive into the 8×12 building, with a 6×8 hot room. The book details sauna building step by step. It is a guide for you to adapt and design your own hot room, not a blueprint to follow an exact plan.

  7. I decided and built a sauna that is 12×12 feet. Well, it is actually 8×12 walled-in structure with 4×12 privacy porch under the same roof on which I set up a bucket shower 🙂 I wanted to be able to get out naked and get that bucket shower, I have always been in love with. That is how I solved it the challenge and not disturb our neighbors.

    But yes, still, 8×12 IS the sweet spot for a sauna.

  8. I too am trying to figure out how to get in my naked cold shower in my back yard (without having to wait for sunset) I just finished my build and have had less than 10 saunas —-but oh, my they are fabulous.

  9. I’m especially interested in the 12 x 16 sweet spot size that you mention in article. Did you have a follow up post discussing that size for a larger lot? Really love reading folks’ building experiences.

  10. Hi Sarah,

    If you type in “12 16” into search bar above, you will see a couple articles and even a layout drawing of a good design of integrating a sauna within this size building. Hope this helps!

  11. I am considering a design replacing of the one short walls into a curved wall made up of 4 x 8 glass blocks which reflects the outside light in beautifully, but unsure if the blocks and the cement will take the heat of the sauna. Have you seen any saunas with glass block features and do you know if they are energy efficient?

  12. My sauna is 7X7X7 wood fired from outside. Great for a couple or 13 folks after a plunge in Lake Superior. Bigger seems a waste of stoking time and wood. My first sauna involved bird hunting Seagrams Seven and Bosch Beer. I’ve been in the UP for 50 years plus because of that sauna. Married a Suomalainen and have had a savu sauna in Kuopio Finland. A little more loylu please.

  13. Just finished our sauna build, made sure this time that we have plenty of room. The hot room is 8 by 10 with the benches along the 10 ft side.
    We heat it with an amazing Kuuma medium and it rocks. cladded on the inside with white eastern cedar (local Ontario).

    We are very happy with our new build.

  14. Hi Glenn,
    I completed my 8×12 sauna this fall just before the snow came in Alberta, Canada. It is fantastic! Your website, blog, and your book were a great asset. Thanks.
    Now that I am using it, I am experiencing a few issues especially since we have been in a deep freeze. For a variety of reasons, I decided to go electric heating it with a 9kw Harvia Cilindro. The issue I am having is excess humidity. While the sauna is on, the hot room is sitting at about 60-65% even when it is very dry outside and all my vents are open. However, the real issue is in the change room where ice is building up on the window, door, and even the walls when it is super cold outside.
    Do you know if this excess humidity is because it is a new construction and all of the building materials are still holding moisture? Have you found this to be an issue in other new saunas? If not, any ideas?
    For other information:
    My hot room has five 4″x4.5″ vents with sliders. While hot, the humidity doesn’t seem to change at all regardless of the level of ventilation.
    When I return the morning after a sauna, the hot room is dry of any visible water spills, smells fresh, etc. The change room, on the other hand, is full of condensation.
    Thanks in advance.
    Steve

  15. Hi Steve:

    I’m glad saunatimes has treated you well, and good on you with your sauna build!

    Humidity:
    I get it! You’re not alone. This is a job for mechanical ventilation. I know it seems like a drag, but you can plow through this after market solution.
    1. Purchase a bathroom vent.
    2. Find a way to 110v. wire it into your existing sauna. I’d install it in the changing room.
    3. Sauna at your own pace and peace. Then, towards the end of your sauna session,
    4. Fire that baby up and it’ll be the little engine that can, over the course of 45 minutes or so, pull all that warmer wet moist air out of your sauna building.

    Your post is timely and inspiring. I’m actually dealing with a very comparable issue here in Minneapolis. hashtag: sauna universality.

  16. I actually provisioned electrical for a vent fan in the hot room, which I haven’t hooked up yet, and could easily tap this line for the change room as well. Any idea if this vent is better off high on a wall, low on a wall, doesn’t matter?

    Thanks again.

  17. Great move on tapping this line for a vent in the changing room.

    I’ve sat chilling out in cool wet steamy changing rooms countless hours in my life. I’m thinking empirically where the best spot for mechanical ventilation should be in the changing room,I’m going to push this question out to a couple fellow deep thinkers, (Walker, Christopher, Kimmo) and hope for their chiming in.

  18. Hi Glenn.

    I’m using your book to build my backyard sauna. I have one quick question. You recommend a sloping floor that moves the water to the drain using cement board on top of sloping wooden sleepers. I want our floor to be flat for multi-use (yoga, etc). I’ve already installed the cement board so it’s a flat floor surface. Would you recommend that I install the wood floor directly on top of that, or should I add sleepers to create a gap between the cement board and wood flooring? We’re also considering sort of framing the floor in sections so that we can lift it up in case water collects underneath.

    Thanks,

    David

  19. Hi David:

    It seems to me that in your case, a flat hot room floor is more desirable than a sloped floor to drain. That’s what you have now, so that’s probably what you want to stick with.

    Given that you’ve already installed the cement board, you could skim coat it (as detailed in my ebook), and then build duck board, or wood slate decking on top (as you detail).

    The idea of a sloped floor with drain is in Finnish style, where a Teemo, or a Jarmo, or a Jari can dump water over their head while sitting on the bench, and all the water can find its way down the drain. Or if in Russia, same for a Vlad or Victor or.. well… you get the idea. And here in USA, if Fred, or Jim, or Frank kicks over the water bucket, all is good in terms of where that water goes.

    If you have a drain in your hot room, well, if this were my project, i’d be doing the sleepers, cement board, vinyl skim coat and get to the stage where, no matter what country the sauna bather is from, you’ll be able to toss or spill water freely. Your duck board or deck flooring could be leveled out atop.

    That said, if you’re planning a dry sauna and mostly hot yoga action, well, you may just keep it flat and go from there.

    I hope this helps!

  20. Thanks, Glenn.

    If I keep it flat, adding a flat wooden floor on top of a flat cement board, would you recommend simply screwing the wooden deck flooring down (into the cement board and sub floor) or raising the wooden deck flooring using sleepers to allow for a gap between the wood and cement board. Or does it matter?

    I did install a drain, if that matters.

  21. Hello again, Glenn. We’re also considering building sections of flooring that rest on a frame so that can be lifted up in sections (it isn’t secured to the cement board or sub floor). Do you see any issues with doing it that way?
    Thanks,
    David

  22. Absolutely good idea.

    Building sections of flooring: I like 2×2 or 2×4 as deck framing, then 2×4 cedar as decking, same as the benches. You’ll find that these lift up sections of raised flooring really help with the feet being warm and water shedding. If you go to this post, you’ll see how we integrate a “raised floor” almost as the third bench, while at the same time avoiding “the bleacher effect.”

  23. Hi ST Nation! I recently my grandparents old simple Iron Range lake cabin back in to the family. It is perfect except it doesn’t have a sauna which I plan to address this spring!

    I will be building a 250 sq ft sauna / boat house combo and could use some advice on hot room size. While I’ve built a couple saunas in the past I am challenged by a need for seating for 7+ (five kids and a dream to have the whole family in sauna together). Any advice on larger capacity hot rooms and how they might fit into a 250 sq ft envelope?

  24. Hi folks – I’m in the preparation stage of building a sauna on my tree farm in midcoast Maine. Have the stove ordered from Lampaa; have my materials and cedar stockpiled; and am finalizing the design (hard core Colonial on the outside, Scandinavian on the inside); foundation is done; now just waiting for a little spring like weather. A question on construction for anyone who has two cents on the matter. I just refinished a bathroom and used Shluter products on the shower. While I’d been planning on well sealed stud bays, standard insulation, and taped foil for the hot room, the shower project made me wonder about putting Kerdi board into the mix, for vapor barrier, insulation and moisture reasons. Anyone use these products on similar on their builds? Thanks!

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