DIY basement sauna construction- An Easy Step By Step Guide 

 January 3, 2023

By  Chris

Sauna has so many health benefits and is an absolute joy to use. But what happens when the next pandemic shuts down the local gym? It happened to us, and we decided we would eventually install a basement sauna.

We had already finished the gym and slowly built up a decent amount of workout equipment just before the covid hit in early 2020. We had the benefit of having a blank canvas because our basement was unfinished when we bought the house.

If your basement is finished, it'll take a little work, but it is doable. This is how I installed our basement sauna and a simple guide to give you an idea of what it will be like when you build a sauna in your basement.

I'm sure the company (Saunafin.com) I bought mine from will agree that I'm not a professional installer. I'm sure I installed our sauna differently than how they intended. But in the end, just like my welding projects, I did it my way.

Steps to build a sauna in your basement.

The first step to building a sauna in your basement is verifying whether you need a building permit. I can neither confirm nor deny whether or not I got a permit for it. ;)

You may also want to verify the residential electric codes.

Disclaimer: Get help if you need it! I'm not an electrician. This is just a guide on how I installed my sauna. You're kit will come with instructions. Follow them! This guide is not intended to be a know all on sauna building. It's highly recommended that you have a qualified electrician tie in your sauna power. It's better to be safe than sorry.

Framing the sauna walls and ceiling.

In Wellington, Colorado, you have to frame the walls as floating walls. That's why you'll see the 3-inch gap at the bottom of our sauna's walls.

The ceiling height was 83-1/2", and our frameless glass sauna door was framed with a rough opening of 27-1/2 x 76-1/2".

Framing Basement Sauna

Supports for the upper bench were framed at the height of 33" at the top and 16" for the lower bench. The heater stud supports were framed at the height of 26". Most of the studs were framed at typical 16" centers.

Framing of sauna bench supports

The inside of the sauna walls with upper bench support stud at 33" at the top and 16" on the top support for lower bench.

I used that 3-inch space to install the inlet ventilation to the heater. I had to trim the baseboard, so I milled out the baseboard trim with a CNC router.

Routering out sauna air inlet.

Routering out sauna air inlet.

Baseboard Trim Sauna vent

Above is the baseboard trim milled out to use as a heater air inlet vent.

Sauna air inlet vent

Looking at the floating wall from the inside to the air inlet vent.

Air inlet inside vent cover installed.

Once the wall was finished, I installed the air inlet vent cover under the heater.

Running the electrical and ventilation.

Your basement sauna will require power for lighting and the heater. The lighting will be 110v power, and the heater will require the same or 220v power. The heater we purchased required 220v with a 30 amp, two pole breaker.

Sauna wire 10-2 Romex

Sauna wire 10-2 Romex

According to the sauna's instructions, a wire capable of 194 degrees and 300 volts was needed. I ended up using Romex 10/2 wire for this.

Sauna wiring.

Sauna wiring.

The wiring for our basement sauna is fed from the breaker to the controller. From the controller, 220v is distributed to the heater.

Sauna controller wiring.

Sauna controller wiring.

A temperature sensor is also mounted 1 to 2 feet in front of the heater on the ceiling. I used a 3/16" drill bit to drill a hole in the cedar to feed the control wire from the sensor to the controller.

Testing the sauna power.

Testing the sauna power.

I framed a small square in the ceiling of the sauna for an adjustable vent that came with the sauna kit. From the air vent, I ran a flexible 3" metal hose to an air register on the outside wall.

Sauna adjustable air outlet vent line.

Sauna adjustable air outlet vent line.

Sauna air outlet vent.

Sauna air outlet vent.

Insulating the sauna.

Insulation is required to hold the heat in the sauna. I used the boxed store insulation bats. You essentially install them between the studs like regular walls. Just cut to fit.

I installed the bats without paper facing. My framing was with 2x4 lumber, so I used R-13.

Installing the reflective barrier.

The sauna kit should have a reflective barrier to help reflect heat into the sauna. It's fairly easy to install. Installation is simple: rolling it out and stapling it to the studs. You'll want to overlap the seams by roughly 3 inches.

The instructions said not to tape the seams. So, I didn't. Who says guys don't read instructions?

Covering the sauna ceiling and walls.

Sauna wall and ceiling covering

Covering the sauna ceiling with cedar seemed to be the way to go. When I started the interior walls, I installed the first course of cedar a 1/2 inch off the flooring as the instructions recommended.

sauna wood unfinished side
Excellent sauna wood finished side

You'll want to ensure you hit each stud when you nail the cedar tongue and groove. You'll also want to nail in the tongue to hide the nails.

Nailing the tongue to hide nails

Along the corners of the interior walls, you can nail anywhere as long as it's within a 1/4" from the corner, as trim will cover the nails.

The nails should be galvanized to prevent rusting with the steam the basement sauna will create.

For the last course, I ripped the board on a table saw at an angle to make installing the last boards at the top easier. I don't know if it's the right way, but it worked for me.

Top strip ripped at angle to get in to tight spot

Constructing the benches.

The benches will be built by marking lines on the walls where your pre-framed support studs were installed. Verify the supports are level and screw them through the cedar and into the studs.

Framing sauna benches

The bench tops should be screwed from underneath to hide the screws and prevent someone from touching the hot metal.

Depending on your basement sauna floor plan, you may have an L-shaped upper. Our sauna was designed for an upper L-shaped bench with a lower bench.

Benches built, backrest and upper skirt installed.

Benches built, backrest and upper skirt installed.

Our kit had a bench skirt to hide the space between the benches. To install the skirt, you can use a laser to mark out lines to keep everything square and level.

I built them outside the sauna with 1" screws from the backside for aesthetic reasons. Once the backers were installed, I nailed the skirt with the finishing nailer between the slats.

I used the excess wood, which was supposed to be door trim for the bottom bench skirt.

Installing the sauna heater.

The heater hangs on two brackets secured through the siding and into the support studs with screws.

Sauna heater installation.

Sauna heater installation.

Once the heater is hung, wire it up according to your kit's instructions.

Sauna heater wiring.

Sauna heater wiring.

After the heater is installed, you'll want to install the rocks. I washed the rocks before placing them in according to the manual.

Heater rocks and heater guard built with 2x2s.

Heater rocks and heater guard built with 2x2s.

Next, you'll want to frame the guard around it to protect users from getting burned.

Installing the floor cedar kit.

Our kit came with an option for a floorboard kit. Once again, you'll want to use screws from underneath for aesthetics. I could have installed the flooring kit before the heater guard; however, we wanted to be able to pull them up for cleaning.

Sauna floor kit and lower bench skirt installed.

Sauna floor kit and lower bench skirt installed.

I essentially made them into sections that fit together like a puzzle.

Trimming out the sauna and sauna door.

The corners of the sauna are trimmed with 1/2" square trim. I trimmed the door for the exterior walls to match the rest of the house's trim.

Ceiling to wall trim installed with picture of thermal sensor

Next, I installed the nice light shade.

Light shade installed.

Light shade installed.

Sauna exterior door trim completed.

Sauna exterior door trim completed.

Break in test.

You'll want to test run the sauna heater for 30 minutes with the door open with nobody inside. The sauna heater has oils and residues that must be burned off before use.

When I performed the test, it set off the fire alarms in my basement. I had to open two windows to flush out the air.

The one mistake I made.

I framed our sauna before I leveled the basement floor. Yeah, I know, a boneheaded mistake to say the least. I had planned for the 1/2" marble tile, but not the 3/4" leveling compound.

It forced me to cut out the door header and the drywall. Not hard, but I wasted time that I didn't have. Don't be me; level your concrete floors before framing the sauna.

First sauna session.

Our first sauna session was killer. It proved that the money was well spent, and the work was well worth every hour (it took me three or four days to finish it). It was especially rewarding to see the smile on my wife's face.

Along with the feeling of accomplishment, it felt cozy, comfortable, and divine! We sprinkled water with eucalyptus on the rocks. It opened my sinuses and got me sweating like I'd stole something.

FAQs On building a basement sauna.

Does a basement sauna need a drain?

According to everything I found online, only commercial saunas are required to have drains on the floor.

Is it cheaper to build your own sauna?

I think it's cheaper to build your own sauna. If you were to hire it out, it would cost you an arm and a leg. There are some cheaper pre-assembled kits on the market, but I know in my heart they're not as lovely as the one I ordered from Saunafin, and you won't get the custom look.

How much does it cost to build a sauna in your basement?

We ordered the top-of-the-line kit from Saunafin with all of the options for a 5 x 6 sauna, and all in, it cost me around $7300, including everything purchased from the local box store. This price includes shipping from Canada to Colorado.

The price is worth it to us as it's an excellent way to relax, and the feeling you get from building it yourself is priceless. You'll get serious bragging rights!

Final thoughts on building a sauna in your basement

Building a sauna is a lot of work and can be expensive, depending on your method. I chose the DIY basement sauna method to save money and have the flexibility to do it my way.

In the end I went from this:

Saunafin kit 1.
Saunafin kit 2.

To this:

Our Basement Sauna

Our Basement Sauna

I can't say enough about the wood that came from Saunafin. I'm sure I could have saved a little extra money by purchasing the tongue and groove locally; however, I doubt I could have purchased a better-quality white cedar than they offer.

Their staff was super helpful and always friendly to work with. If I had to do it again, I'd go the same route, but I'd level the floor first!

If you're thinking of performing a basement sauna install, check their kits out and do it. Basement saunas aren't challenging to install if you have a little skill.

Hopefully, this guide gave you insight into what's involved with DIY basement saunas. If you are building a sauna, how's it going? We'd love to hear how your project is going.

If you're shopping for a quality sauna kit, get in touch with Saunafin at 1-800-387-7029 to see what they can do for you.


Average guy that likes to build things and teach others what I learn. Family comes first. Steel, Jeeps and off-roading are all fighting for second place.

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