Adding a sauna to your home is a good way to both improve your home's value and to add an area for rest and recreation. To convert a room into a sauna, it must be sealed, framed, wired, and insulated, then finished with paneling, benches, and a tight door. There are tricky aspects to the build, such as the electrical wiring and bench design. However, saunas are a relatively simple and easy conversion project.
Things You'll Need
- Vapor barrier, 6 mil minimum
- 2 x 4 or 2 x 6 floor joists
- 2 x 4 wall and ceiling studs
- Electrical wiring
- Ground fault electrical outlet
- Light switch (optional)
- Bathroom rated light fixture (optional)
- Fiberglass insulation
- Tongue and groove paneling boards
- 1 x 4 bench lumber
- Sauna stove
- Sauna door
Seal the room for moisture by stapling a vapor barrier to all room surfaces: the wall, floor and ceiling. Saunas, especially if you are installing a steam sauna, create humidity that must be isolated from the rest of the house.
Install floor supports over the floor vapor barrier. Leave enough space between the floor supports to install your insulation. Most common fiberglass insulation is available in either 16 inch or 24 inch wide rolls.
Install studs over the wall vapor barrier. Leave enough space between them for insulation.
Install ceiling studs by nailing them to the wall studs. Again, make sure there is enough space between them to easily roll out insulation.
Install the electrical wiring for the heating stove. In some jurisdictions, you may need to hire an electrical contractor for this, see Tips. If you need a light inside the sauna - for example, if the door will be solid, with no window to allow in outside light - make sure there is an existing light fixture and switch, or wire them in.
Insulate the walls, floor and ceiling with fiberglass insulation. Insulation both reduces the cost of operating your sauna by keeping the heat inside the room and prevents other areas of your home from becoming too warm from heat escaping from the sauna.
Install paneling boards over your newly insulated floor (see Tips for paneling materials). Tongue and groove boards will help to keep moisture from seeping down into the floor insulation and will help to make a solid, stable floor. If you have a router, you can cut the tongue and groove into the boards yourself.
Nail your first ring of tongue and groove wall boards to the bottom of your studs: horizontally, tongue up, groove down.
Install your wall boards in layers, fitting the grooves over the tongues and moving up the wall until you reach the area where the outlet for the stove will be installed. Cut the board to accommodate an electrical outlet and mount that board in two pieces. Once you have the appropriately sized opening, install the outlet.
Continue installing your wall boards, fitting the grooves over the tongues. If necessary, cut the paneling around the light switch. Add layers of paneling until your insulated walls are covered.
Begin on one side of your ceiling and nail your tongue and groove boards across the ceiling until it is covered. If necessary, cut a hole in the ceiling boards near an existing light fixture and extend the wires downward. Once the ceiling is installed, install a waterproof bathroom light fixture.
Build your sauna benches. See Resources for examples of bench design. Most sauna benches are at least 19 inches deep and have two levels, the higher being a hotter level and are constructed of 1 x 4s over a 2 x 4 frame. In some cases, you can attach the sides of your benches to the studs in the wall, however it may be a good idea to build additional 2 x 4 supports at the center of the benches, depending on the size of your sauna and the length of your benches. It is better to overbuild your benches than to underbuild.
Install your sauna stove per the manufacturer's instructions. In general, a stove should not be installed less than four feet from the bench.
Install a pre-made sauna door. Pre-made doors can be solid or have a window to allow light in to the sauna. Some sauna door kits come with pre-made frames; however, in some cases, you may need to frame in the door. Install the frame, and then hang the door. If the door does not quite fit the frame, plane down the door until you get a tight fit.
Tips & Warnings
- Make sure the wood you use is rated for high humidity environments, especially if you are making a steam sauna. Cedar is naturally resistant to rot and also offers a pleasant aromatic smell, so it's very popular. Other popular woods include Nordic white spruce, clear aspen, or hemlock. Keep your stove at least four feet away from the benches. Most small sauna rooms will work well with a 120V sauna stove. However, larger rooms may require a 240V stove. If you are using a 240V stove, you will likely need to have a licensed electrician install the wiring. There are two general types of saunas: Dry saunas and wet saunas. A stove designed for a wet sauna will have rocks on the top and will have a barrier to keep the water off the electrical components of the heater. In a wet sauna heater, the rocks heat up. When you pour water over them, the water turns to steam, increasing the humidity in the sauna.