How to build a sauna

DIY sauna builders – Here’s how to build a sauna either with a pre-cut sauna kit or using sauna plans and constructing a sauna with raw materials.

Home Made Sauna Planning And Design

Plan your sauna by asking yourself these questions:

1. What kind of sauna do you want?  Do you want a built in sauna or freestanding.  Do you want an infrared heater or traditional sauna heater.  See sauna heater reviews.

2. What size sauna do you want?  How many people do you plan to have in your sauna.  Smaller saunas have more efficient and quicker heating.  You should allow 2 feet of bench space for each person sitting.  For reclining, you’ll need 6 feet per person.  The ideal height for the sauna is 7 feet.

3. What shape do you want?  Although most saunas are rectangular or square, you can also install round units or units with angled corners.  Your space may determine the shape sauna that you can use.

4. Do you want windows?  Windows will effect the efficiency of the sauna heat, but they are nice for making the sauna seem much more open.

5. Where will you place the sauna?  Inside, outside, near bedrooms or exercise rooms, near the pool or bathroom.

6. What type of wood?  Soft woods like cedar, fir, spruce, and redwood are excellent choices.  They work better than hardwoods and they smell good.  The wood should be kiln dried to less than 10% moisture content to reduce warping and shrinking.

Sauna Kits

A pre-cut sauna kit offers a great degree of flexibility when you’re building a sauna because it allows you to custom design your sauna layout to fit any location. in fact, kit manufacturers like Great Saunas, offer to make custom design changes to their pre-cut sauna kits.

DIY pre-cut sauna kits offer cost savings on labor because you perform most of the work yourself.  Expect to spend about $3,000 on a typical 5’x7′ pre-cut sauna kit.  This can save as much as $2,500 compared to a pre-built home sauna.

To build a sauna you’ll need only basic tools such as a circular saw, hammer, level, measuring trape, power drill, utility knife, pliers, and screwdriver.  Be sure to compare sauna kits carefully.  Some come with everything needed, while others may not include expensive components such as the sauna heater or controls.

How To Make A Sauna

Choose Your Sauna Location and Size.  It’s a good idea to draw the layout of your sauna on the floor to see how the sauna will look and fit once the sauna is built. The location should be level and have access to a 240-volt electrical supply. The electrical needed is similar to a clothes dryer or electric stove.  Circuit breakers needed will be 30 or 40 amps for most home saunas.

Building The Sauna Floor.   Saunas require a Base Floor and a removable Duckboard Floor.  For indoor saunas, an existing concrete floor sealed with a waterproof sealer will work as the base floor.  The stud walls will sit directly on this floor.  Outdoor saunas will need a concrete foundation and sloped floor.

The Duckboard Floor consists of removable sections of 1x3s or 1x4s called duckboards.  These wooded slats will have 1/2″ spaces between them for air and cleanability and to make them easy to remove.

A floor drain in your sauna can be complicated and can get expensive. Many home saunas do not have floor drains. Water will usually evaporate quickly from the floor, but be careful not to ladel too much water over heater rocks and create pools.

Sauna Wall Framing.  Build the sauna walls as free standing frames using 2×4 studs on 16″ centers.  Allow for air vents and a rough opening for the door of 26″x 75″.  If you want windows, allow for them in the framing.  Once the frames are built, raise each and attach to the concrete floor with concrete anchors.

Frame for a drop ceiling to give the finished sauna a ceiling height of 84″.  Frame the ceiling with 2x4s at 16″ on center.  Note: Do not exceed 7′ for the ceiling height of your sauna.  Heat will rise and fill the space above this 7′ level creating a major inefficiency for your sauna heating and requiring a larger, more expensive sauna heater.

Sauna Insulation & Wiring.  An electrician needs to install the sauna heater electrical circuits, lighting, controls, and thermostat.  Sauna heaters may have the controls built-in to them, but it’s better to relocate controls to the outside of the sauna for convenience, safety, and long life.  The wiring must be rated for 90°C (194°F).  Locate the wiring on the “cooler” side of the sauna walls.

After  wiring is installed, aluminium foil vapor barrier is installed.  Special high temperature aluminium foil vapor barrier with the shiny side facing in towards the sauna, is installed.  This keeps moisture from collecting on the walls and the shiny side reflects heat back.  You’ll probably need to source this special vapor barrier from a sauna material supplier.

After the foil vapor barrier, conventional fiberglass batt insulation is installed.  Batts are usually 15″ wide.  Choose an R13 insulation for the walls.  For the ceiling, you need R22 or R26.  You can achieve this by using R13 batts and laying them in 2 layers perpendicular to each other.

Sauna Windows and Doors.  Sauna doors always open out for safety. A standard sauna door is relatively narrow and short at  24W”x72H”.   The door handle should be matching wood and you should use a friction door catch not made of metal.  It’s probably best to buy a factory made sauna door from a sauna dealer since constantly changing heat and humidity will warp a homemade door.  Factory sauna doors are available with windows too.

Sauna windows made of single glazed tempered glass can be installed in the walls.  Double glazed glass windows will fog up. You need to allow some space for window frames to expand when they heat up, otherwise you risk cracking the glass.

Interior Walls.  Line the interior walls of the sauna with tongue and groove cedar 1×4 or 1×5 boards, running either horizontally.  Attach with 1 1/2″ rust-resistant nails, nailing into the tongue of each board at an angle.  Make sure to countersink any nails.

Western Red Cedar is good for building a home sauna in North America.  It’s light in color, withstands changes in humidity, absorbs perspiration and smells good.  Exterior sauna walls can be made of various materials and can be painted or stained.

Build Sauna Benches.  After the interior wall lining, you can build benches.  Sauna benches should be thicker material than the walls, typically 2x2s, 2x3s, or 2x4s.  Use cedar planks attached to wall cleats and legs with screws.

Sauna benches are usually arranged in an upper and lower bench layout that allows you to change location to a warmer or cooler spot.

Leave 1/2″ air space between bench planks.  Lower level benches are typically 17″ wide and should sit 18″ above the floor.  Upper level benches are 20″ wide and should be at 46″ from the ceiling to allow enough headroom.  If your upper level bench is 18″ above the lover level bench, you should have enough space in a 7′ high sauna.

Sauna Heaters. Sauna heaters or sauna stoves can be electric, gas, or wood burning.  All heaters should use use granite or other igneous rocks for safety reasons – See Sauna Replacement Rocks.  Compact wall mounted heaters are typical for smaller home saunas.

The sauna heater needs to be sized correctly and it needs to be installed by a certified electrician.  If you install an undersized heater, you’ll have trouble with the high-limit control tripping.  If the heater is too powerful for your sauna, your sauna bathers will be subjected to searing heat.

A quick rule of thumb for determining the right size sauna heater (in an 84″ high sauna) is to divide the cubic feet of your sauna (for example, 5′ x 7′ x 7′ = 24 cubic feet) by 50 to get the appropriate size of a 240 volt heater in kilowatts (Kw).  In our example, 245 divided by 50 is about 5 Kw.  In other words, you need about 1 Kw for each 50 cubic feet of space to heat.

Small electric sauna heaters (110 volt) are designed for 1 or 2 person saunas.  Saunas larger than that require 220 volt heaters.  Electric sauna heaters range in size from 2 Kilowatts to 18 Kilowatts.

Wood burning sauna stoves are natural and traditional sauna heaters.  They are a lot more work to tend and maintain and they require up to 1 1/2 hours to heat up – compared to 30 minutes for an electric heater.

You can also choose a gas sauna heater, though they are expensive to install.  Gas heaters require gas lines for natural gas or propane along with propane tanks to be installed outside the sauna.  You will also need to vent the exhaust through a chimney.  Gas sauna heaters are sized in BTUs with 1,000 BTUs needed for every 15 cubic feet of sauna room space.

Sauna Lighting.  A 60 watt single bulb light fixture is sufficient for a sauna.  Be sure to use an aluminum base light bulb with a heavy duty glass globe on the fixture.  Lighting should be comfortable with no light directly in your eyes or too bright.  The best location is a wall off to the side rather than a ceiling fixture.

Sauna Vents.  To distribute heat evenly in the sauna, you need venting.  Create circulation with an intake vent at the floor under the heater and exhaust on the opposite wall.  Use a 3″x 10″ duct space for 30 square inches of air flow.

You can also build a hollow space inside the framed wall to act as an air duct. Then locate the vent anywhere you need.  After your sauna is finished , clean out all debris. Run the sauna for two hours at 80 °C (180°F).  This will burn off coatings on the heater elements and will check the sauna rocks too.

How To Buy A Sauna

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