Introduction: DIY Outdoor Sauna

Hi guys,

I wanted to share with you my outdoor Sauna build. It's inspired by a log cabin and simple to build. It took my 2 weekends to finish. Measurements are around 1500*1500*2000mm / 5*5*6.6ft. This build is suited for 1 to 2 Sauna guests. Overall, I kept the costs below 1000$ by using a 2nd hand stove and cheap timber beams.


  • approx.100 wooden beams (1500*80*50mm) for the wall and ceiling
  • 5 * 10mm steel rods with washers and nuts
  • decking boards and wooden struts for the flooring
  • gravel
  • concrete slabs
  • Bitumen roofing felt
  • planed planks and wooden struts for the bench
  • wood burning Sauna stove (Harvia M3)
  • steel chimney pipes
  • Sauna door with glass
  • 5m LED strip
  • wood glue
  • different kind of wood screws
  • Tools: Flame scarfing device, electric drill, hammer, knife,...

Step 1: Groundwork

First, you need to do the groundwork. I decided to go for a simple foundation. Depending on the nature of the ground, you might need to go for a more stable solution like a concrete foundation.

  • Excavate soil
  • Fill with gravel
  • Put concrete slabs in each corner flat on gravel
  • Make sure that all slabs are at the same height and level

Step 2: Floor

Second, you need to do the flooring of the sauna. I used decking planks, as they are robust and good looking. Moreover, you can walk on them barefoot.

  • Make a wooden frame; the frame is sized onetime the length plus the width of the beam; I used 1500*80*50mm beams, so my frame was sized 1550*1550 mm (1500+50mm)
  • Screw the decking planks on the frame
  • Cut the decking planks in size

Step 3: Walls

Now you need to build the side walls of the sauna.

  • Drill holes at one end of the timber beams. The hole is for the steel rod which helps to align the beams.
  • Make a template for the drilling (I used a thick steel plate). The hole needs to be drilled in the middle of the width of the beam half the width away from the end. I used timber beams with 50mm width. Thus I needed to drill the holes 25mm away from the end of the beam.
  • Screw the first row of timber beams on the wooden floor. Make sure that at each corner as well as at the door opening a steel rod is inserted
  • Stack the next layers on top using the steel rods and wood glue. In order to make the walls more stable stack the beams in an offset fashion. Overall, I stacked 24 rows

Step 4: Roof

For the roof I used the same timber beams as for the wall. However, I didn't drill holes.

  • Screw the first beam on the top of the walls
  • Connect the other beams by using wood glue
  • Screw the final beam on top of the walls
  • Cut bitumen felt roofing in size
  • Put the bitumen felt on the wooden roof
  • Use the flame scarfing device to glue it to the wood

Step 5: Exterior - Shou Sugi Ban

To keep a natural look I decided to go for a traditional Japanese technique for the exterior: Shou Sugi Ban. Basically it means burning the wood to increase its longevity and give it a cool dark look.

  • I used the same flame scarfing device as for the bitumen roof
  • WARNING! Be careful not to burn your Sauna to the ground! keep a fire extinguisher near you! After finishing keep an eye on your build to make sure that no fire starts!

Step 6: Door

The most expensive part of my Sauna build was the glass door. You can keep the costs down by using a wooden door.

  • You should insert the door with a partner, as it is quite heavy (and glass tends to break)
  • The door should open outwards
  • Screw the doorframe to the walls
  • Add hinge cover and door handle

Step 7: Interior - Sauna Bench

You can buy a Sauna bench but I wanted to create also the interior myself. In addition, it is cheaper and made to fit.

  • Cut a frame in size. I used 2 longitudinal struts and 4 cross struts. The width of the bench should be around 600mm/2ft
  • Use wood screws to assemble the frame
  • Screw the frame on the wall. I put it at a height of around 600mm/2ft
  • Use planed planks for the top. Screw them on the frame.
  • Install a RGB LED strip for the lighting. You can remotely control the color which helps to create a cosy atmosphere.

Step 8: Interior - Sauna Stove

Now it's time for the most important part, the wood burning stove.

  • Put a protective plate under the stove
  • Mark the outlet of the chimney on the wall
  • Drill a hole for the outlet in the wall
  • Seal the connection between stove and steel chimney up
  • Install the chimney

Step 9: Final Steps

Just a few steps are now missing.

  • Add stones to the Sauna stove
  • Install a thermometer/hygrometer and hourglass
  • Tighten the screws on top of the steel rods
  • Cleaning

Step 10: Enjoy!

I hope you had as much fun reading my outdoor Sauna Instructable as I did building it. Maybe it inspires you to build your own Sauna. If you like this Instructable feel free to give it a like.