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How to Convert a Shed Into a Sauna

Updated on November 18, 2017
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Out of personal experience, Chris writes articles about how to make items and accomplish tasks which are practical, helpful, and proven.

How to Turn a Shed into a Sauna

This article describes how to turn an existing shed or outbuilding into a sauna. The following information is covered:

  • Vapor barrier
  • Insulation
  • Interior wall boards
  • Ventilation
  • Wood stove

The Shed We Converted Into a Sauna

This photo shows WHAT we wanted to turn into a sauna, and WHY
This photo shows WHAT we wanted to turn into a sauna, and WHY | Source

The Idea

My sons and I had been talking about turning that small shed in the back yard into a sauna for years. Finally in the fall of 2009 we made our move. We each did some research and then set to work building a sauna of our own. Read on to discover how to turn an old shed or an outbuilding into a sauna.

View of Insulation, Moisture Barrier and Cedar Wall Boards

My son Scott.  He did a wonderful job on the sauna.
My son Scott. He did a wonderful job on the sauna. | Source

The Insulation

The first thing we did was to get some insulation for the walls of the shed which we were converting into a sauna. We used rolled, fiberglass insulation for both the walls and ceiling. Insulation is described in terms of its “R” value. R13 is good for the walls of a sauna and R26 for the ceiling. Use the same insulation in the ceiling as for the walls, using two layers running the top layer perpendicular to the previous layer.

Aluminum Foil Moisture Barrier

The project is moving along nicely.
The project is moving along nicely. | Source

The Moisture Barrier

Next came the moisture barrier for the sauna which is made of aluminum foil. These specially made foil barriers can be hard to find and are expensive. We solved the problem. Gordon Food Services sells large rolls of heavy duty aluminum foil. We built the sauna in 2009 and now it is 2013. I’m still using the aluminum foil in the kitchen. The foil used as a moisture barrier for the sauna must be put on with the shiny side facing the interior of the sauna so that it reflects the heat back into the room.

Installing the Ship-Lap Cedar Wall Boards

Nice Job Dan (my younger son).
Nice Job Dan (my younger son). | Source

The Cedar Wall Boards

Next we looked for cedar boards for the interior. We could have gone to a lumberyard and gotten tongue and groove boards, but those are expensive. My sons looked around and found a small, local mill that had a stack of unfinished cedar boards sitting outside. We had the boards planed and brought them home. The question now was, how we would connect the boards. Would we tongue and groove them ourselves, overlap them or find another way? As we discussed it, we came up with a design that we later found actually has a name. It is called shiplap, and it is made by cutting the edge of the board into an L shape. On each edge of the board, the L faces the opposite direction. As the boards are put into place, opposite facing Ls overlap. Our sauna was becoming a reality.

Ship-Lap Cedar Wall Boards


Preparing the Door

Dan working on the door of the sauna.
Dan working on the door of the sauna. | Source
We were able to get this excellent used stove for no charge.
We were able to get this excellent used stove for no charge. | Source

The Wood Burning Stove

The sauna stove was the next part that needed to be done. We covered the wall space near the stove with cement board and in addition we lined the wall closest to the stove with paving bricks stacked on edge. You will need to check local codes for the distance required between the sauna stove and wall. We ran the stovepipe through the wall at stove level and then up the outside of the building. This required a lot of custom work that wouldn’t necessarily be helpful to anyone else. Be sure to get the proper pipe for going through the wall, as it needs to be double walled pipe so that the heat is reduced where the pipe comes into contact with the wall. Also remove any material on or in the wall around where the pipe passes through that is not fireproof. If it is even close, it will catch on fire.

The Floor

If you are planning to convert a shed into a sauna, the floor might take some special attention. The work on the floor ranges from replacing it to doing nothing. What is the condition the floor before beginning work? Are there gaps between the boards? Is it already a tight fit?

The floor of our shed had half-inch gaps between the floorboards. This was going to allow lots of cool air to enter our sauna, thereby making the lower part cooler than the upper. We chose to use fiberglass strips and resin. The problem has been that the finished floor holds a lot of heat. I suggest laying down well-sanded boards on the old floor and installing a drain. The sauna's heat will dry the wood, preventing any problems associated with moisture.

Another suggestion is to pour a concrete floor and install a drain. Over this, install raised, slatted wood floors. These could even be removable for cleaning purposes.

The Finished Sauna: A Job Well Done

Job completed.
Job completed. | Source

Enjoying the First Sauna

Look!  It works!
Look! It works! | Source

The Stove and BTUs

Choosing the sauna stove is quite complicated it seems. It depends on the construction of the sauna, window and door space, ventilation, outdoor temperatures and the construction of the sauna stove itself. The figures for determining the BTUs needed to heat the sauna are as follows: Cubic feet to be heated (Length x width x height = Cubic feet); Temperature change (Maximum desired inside temperature minus the lowest expected outside temperature). Follow the link on the right, enter the data and get your BTU information.

Ventilating the sauna

We chose to put one vent in the sauna, and we located it near the ceiling on the opposite end of the sauna from the door. At the bottom of the door we allow outside air to enter the sauna while the warm air escapes through the vent near the ceiling of the sauna.

As Simple as That

A sauna is relaxing and fun to use. When you entertain guests at your house, have them bring their swimsuits along so you can all enjoy a sauna together. Good luck on your next Do-it-yourself project, whether it is turning an outbuilding into a sauna or some other cool addition to your home.


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    • cam8510 profile image

      Chris Mills 2 months ago from Maple City, Michigan

      Scott, sorry it took me so long to get back to you. We used blue board for insulation, then added the foil moisture barrier, then the cladding. We don't see much warping. The door works fine. I hope that helps and is in time for your project.

    • profile image

      Scott 2 months ago

      Hi there,this is exactly what I'm looking to do aswell,but I have a question about the door to the sauna, did you just put cladding on the inside of the existing shed door or did you insulate that aswell? Also if it's the original shed door does it not warp with the heat? Thanks and great job by the way

    • cam8510 profile image

      Chris Mills 2 months ago from Maple City, Michigan

      Heidi, First we cut a drain hole in the floor. Then we used fiberglass strips and resin which come in a kit. You could also try a vinyl concrete floor. It comes in bags to mix in a wheel barrel or in ten-gallon buckets already mixed. begin thicker at the walls and slope toward the drain. Here is a good website for the floor. http://www.saunatimes.com/building-a-sauna/a-great...

      Good luck with your sauna. Enjoy.

    • profile image

      Heidi 2 months ago

      What did you use on the floor to keep it from rotting from water? I'm building one out of a existing shed that has plywood flooring already installed. Thank you

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      jitendra singh 4 months ago

      Very nice

    • cam8510 profile image

      Chris Mills 14 months ago from Maple City, Michigan

      Faith, Down here you would get a couple months use out of a sauna. It's not enough to justify a large expenditure, but a small outhouse sized sauna would not cost much. My sons did most of the work. I just paid for it.Thanks for stopping.

    • profile image

      Faith Reaper 14 months ago

      Wow, Chris, this is so cool ...um ...hot! What a great idea to turn a small shed into a sauna. I would love one, but living in the Deep South ...not to practical for outside here, although it does dip down into the low 30s and lower at times.

      It's great you and your sons worked on it together too. I love the photos you included here, especially of the snow contrast against the shed. I would certainly have to build myself a sauna if I lived in such cold areas with that much snow!

      Great job!

    • profile image

      Chris 18 months ago

      Outdoorsaunamndiy, congratulations on finishing your project. You are going to love it. Regarding the foil, I think we jumped on the first thing that was cheaper than the alternative. Thanks for reading the article and for your feedback.

    • profile image

      outdoorsaunabuildmndiy.blogspot.com 18 months ago

      Hi, great build! It's blogs like yours that inspired me to build my own outdoor sauna. I see you used foil-- I went the bubble foil route. Either way, I can't wait till winter now :)




    • cam8510 profile image

      Chris Mills 20 months ago from Maple City, Michigan

      ALLY BABAY, Well, there is a question I haven't thought about in a while. All I can say at this point is that I remembering setting a budget of one thousand dollars at the time. I have to believe we came in under that amount.

    • profile image

      ALLY BABAY 20 months ago

      How much did it cost you to build? Thank you for sharing this project.

    • cam8510 profile image

      Chris Mills 2 years ago from Maple City, Michigan

      chef-de-jour, sorry I missed your post from a month ago. Sounds like you had a workable sauna situation in Scotland. I'm away from home working on the road full time now and rarely get to use the sauna. But when I'm done out here on the road, I'll be relaxing quite often in the cozy warmth. Thanks for checking in here.

    • chef-de-jour profile image

      Andrew Spacey 2 years ago from Near Huddersfield, West Yorkshire,UK

      When I lived in Scotland many moons ago the rented cottage near Edinburgh had a sauna in the old cellar! It was electric and ate money but every so often I'd pop down for a good sweat and flush out. I love saunas- your conversion job is ace. A great family effort.

    • cam8510 profile image

      Chris Mills 4 years ago from Maple City, Michigan

      Jimmar, good for you. I hope you get many years of use out of your new sauna. It is so much more special when you have built it yourself. Thanks for stopping by.

    • jimmar profile image

      jimmar 4 years ago from Michigan

      did it! turned that useless shack into something useable. I wish I read your hub before I started building. I just winged it, but wasn't too far off.

    • cam8510 profile image

      Chris Mills 4 years ago from Maple City, Michigan

      Randi, we had a blast working on the sauna. After we got it all finished, we went to the beach near here on Lake Michigan and collected basalt rocks to put in the cage on top of the stove. They hold the heat so that when we throw water on them, we get a rush of heat and steam. We really do enjoy our sauna.

    • btrbell profile image

      Randi Benlulu 4 years ago from Mesa, AZ

      Interesting and impressive! What a great project!

    • cam8510 profile image

      Chris Mills 4 years ago from Maple City, Michigan

      mr-veg, Thank you for visiting my hub, and I am happy that you find it to be useful. Thank you for the vote and for sharing.

    • mr-veg profile image

      mr-veg 4 years ago from Colorado United States

      A Job well done !! Great work Chris and thanks for sharing such a nice and useful information. Voted up and sharing !!

    • cam8510 profile image

      Chris Mills 4 years ago from Maple City, Michigan

      Deb, we borrowed a table joiner and it worked like a charm. It is amazing how much can be learned if we are just willing to try doing these projects on our own. I'm proud of my sons for how motivated they were to attempt this project. So you did remodeling for a living? It is so gratifying to see an old home like ours take on new life. Ours was built in 1896.

    • aviannovice profile image

      Deb Hirt 4 years ago from Stillwater, OK

      What a fantastic project, Chris. Wow, had I only known, I would have been more than happy to do the cuts on my sliding compound miter saw. I have done MANY different kinds of cuts when I was doing remodeling for a living. I loved doing shiplap! Can't beat the smell of cedar!

    • cam8510 profile image

      Chris Mills 4 years ago from Maple City, Michigan

      Thanks Rosemary, It was a fun project, and using it never gets old. I hope someone who reads the hub decides to go for it and turn that useless shack out back into something they will use for years to come.

    • Rosemay50 profile image

      Rosemary Sadler 4 years ago from Hawkes Bay - NewZealand

      A great family project, you all worked hard on this and now you can all enjoy it.

      A job well done and great instructions

    • cam8510 profile image

      Chris Mills 4 years ago from Maple City, Michigan

      Austinstar, that is a pretty good combo. Hot tub for relaxing the muscles and a pool to beat the heat.

    • Austinstar profile image

      Lela 4 years ago from Somewhere in the universe

      Oh, man, we have ice houses in Spades! When I was young, you couldn't throw a coke bottle 10 feet without hitting one.

      But I do have an above ground pool (matches my double wide) and I recently purchased a hot tub spa. That's the best I can do.

    • cam8510 profile image

      Chris Mills 4 years ago from Maple City, Michigan

      Austinstar, I wouldn't recommend a sauna in Texas. Maybe an ice house would be more appropriate. Thanks for stopping by.

    • cam8510 profile image

      Chris Mills 4 years ago from Maple City, Michigan

      Eric, thank you. We had a great time working on the sauna. We each had a key role. Mine had to do with $$$. Now we enjoy taking saunas as often as we can together. I do have very good relationships with my sons. Go for it Eric. Make yourself a sauna. There is nothing like it for relaxation. Watch the temperature though. We had it up to 213 f a couple of nights ago.

    • Ericdierker profile image

      Eric Dierker 4 years ago from Spring Valley, CA. U.S.A.

      Chris, do not take me wrong here; I got teary reading this article. It is awesome how you laid out the construction and the pictures fit in perfectly. I am contemplating doing one.

      But it just got me all emotional to watch and learn of father and sons enjoying each others contributions and company. That is what it is all about!!

      So I should say "my sons and I are contemplating"

    • Austinstar profile image

      Lela 4 years ago from Somewhere in the universe

      What a clever idea. Of course, living in Texas is like living in a sauna anyway. All you have to do is go outside. But yours looks very nice and cozy.