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How to Build a Sauna | Converting a Room to a Sauna

Follow these steps and videos to convert an existing room into a sauna

This informational article and videos demonstrate how to tack up your sauna foil, attach cedar paneling to the interior of your studs, mount your sauna heater, install your sauna benches, hang your sauna door, and finish trim and entry walkway.

We sell a DIY precut home sauna kits (sometimes callled "liner kits").  If you have your own lumber then of course, use it up and cut and build your own. Indoor saunas require lowering the ceiling. If you prefer, not to lower your ceiling height. Then, consider the DIY prefab modular sauna kits. These kits use 6'8" wall panels, and are often placed in a larger room, basement, cabin or sometimes under an outside shelter. Also see how to measure and order a precut sauna.


How to Build a Sauna in your Home — Hover over each pic with a still mouse to read the caption, or watch the videos at right

Home sauna room is insulated and ready to be wired for lights, sauna heater and controls Cedarbrook Sauna builder shows how to lay the sauna foil over the insulation and staple it to the bare studs Sauna room has foil on the ceiling and walls, and we started attaching the cedar paneling to the ceiling Cedar paneling is attached to the walls starting at the floor The last cedar paneling board deserves extra attentionIf heating your sauna with an electric sauna heater, then have your electrician thread your wire through the sauna wall Follow your sauna heater manufacturers template for mounting your heater on the wall Use your template and drill your holes for your bolts Measure the distance from the floor to sauna heaters mounting brackets Hang your sauna heater onto the wall screws Position your sauna rocks into the heater Add the grill to the top of the sauna heater Install the sauna benches, high and low Sauna staff discuss the rough opening for the sauna door Hang your sauna door with a helper so the door is square and plumb Saund door is flush with the frame, so cedar trim covers the gap between the wall Set the sauna door handle Setting the self-closing hinge for the sauna door Finishing the corner and seam trim inside the sauna Assembling the precut sauna duckboard flooring kit for the entry way Set the sauna duckboard flooring in the entry way Outside the sauna test all controls and electrical panel

If we can be of more help, please email us or call us at 1.800.426.3929 or read on. Thanks!

Tools & Supplies You'll Need to Build an Indoor Sauna in a Spare Room:
  • Sauna Foil Vapor barrier
  • Nails and nail gun, aircompressor
  • Fiberglass Insulation and Foil barrier
  • Electrical wiring, gas pipe, or a wood pile (for heat)
  • Ground fault electrical outlet
  • Light switch (optional)
  • Wet/dry rated light fixture (optional)
  • Tongue and groove cedar paneling boards. Buy a home sauna kit (view common sizes: 4x6, 5x7, 6x8) or buy your own lumber
  • Cedar bench lumber
  • Sauna heater (view some economical Polar HMR heaters)
  • Sauna door (view sample sauna doors)


Prior to building your sauna room, scan our planning your sauna and the sauna venting and framing article.

This article assumes you've removed any drywall and are now down to bare studs in the room, and bare joists on the ceiling, and a non-permeable floor. Tile, cement, vinyl are suitable non-permeable floors. Plywood will work, but it's good to at least put some tile under your sauna heater. Or anywhere water may accumulate. If you must go with plywood, definitely overlay with duckboard flooring.

How to Build a Sauna: Wiring for Light

Wire your room for a light, light switch, sauna heater wire conduit, and perhaps controls outside the room. If preparing for a gas sauna heater, then you're using gas pipe and you'll have to consider the thickness of the pipe and how many other appliances share the gas line. Consult your gas professional.

How to Build a Sauna: Insulation to Lower Operating Costs

Insulate your walls with R-11 insulation for interior walls, and R-19 for exterior walls. Fiberglass insulation is available in either 16 inch or 24 inch wide rolls. Insulation lowers your operating costs by keeping your sauna heat in the sauna, so don't skip this step. And sauna insulation will also provide a sound barrier, so you relax more deeply which is what it is all about, as well as a good healthy sweat.

How to Build a Sauna: Foil to Reflect the Heat

We attach the sauna foil to improve insulation and as a vapor barrier

The sauna foil vapor barrier adds a R-1 value to your insulation factor, and acts as a vapor barrier. Staple the foil vapor barrier to all interior surfaces, ie the wall and ceiling. Generally, we overlap the foil by 3 inches eliminating the need for the foil tape. Also don't substitute another product for the foil. The foil will never melt and is odorless.

A vapor barrier protects your walls from absorbing vapor. Some steam in a sauna room is great to help bring on a sweat, but it creates humidity that should be isolated from the rest of your house (or spa).

You want that steam to exit through the vent, some is absorbed by the cedar and will dry out eventually. Of course, leaving your heater on longer will dry your sauna interior more quickly. Some sauna bathers keep their sauna heater on longer for this reason.

How to Build a Sauna: Cedar Paneling

Cedar tongue and groove paneling to ceiling and walls

Begin on one side of your ceiling and nail your cedar panel boards perpendicular to the joists. Move across the ceiling until covered. As needed, cut a hole around the light box. Best if your light and switch are wet-rated.

Next, nail the clear cedar paneling boards over the insulation and foil barrier. Nail your first row of tongue and groove wall boards to your studs horizontally, tongue up, groove down. Start from the bottom and move up. Generally, you only need nail the tongue after fitting it snugly over the prior row. This way the nail is hidden by the groove covering it. Vertical paneling is possible, but requires either plywood sheeting over the studs or some strategically spaced horizontal studs over the vertical studs.

Add your cedar panel boards in rows, checking for level every 4th board or so. Fit the grooves over the tongues and continue up the wall. Along the way, you may need to cut for electrical junction boxes for lights, switches, etc. That's the beauty of cedar, it's soft to work with and cuts easily. Continue installing your panel boards until your insulated walls are covered. At the last row butting the ceiling, remember you need not be perfect. If you're within a quarter inch you're fine. The trim pieces will cover any gaps.

How to Build a Sauna: Centering the Sauna Heater on the Wall

Review centering and mounting the electric sauna heater

We are mounting a Polar HMR 60 in our sauna video. The heater comes with 4 screws to secure it to the wall 2 long and 2 short. Always use the longer screws at the top. They have more tension on them and will secure the sauna heater to the wall.

I've marked my holes and will put in the two top screws. Don't seat these yet. Additionally, don't screw in your short screws for the bottom key hole brackets yet.

We have 6" of clearance from the floor for this model according to the manufacturer's installation manual. Once the sauna heater is hung on the wall, we add our 2nd pair of lower screws.

Finally, have your electrician wire the unit to the power source.

How to Build a Sauna: Mount the Sauna Heater

Adding the sauna rocks to the electical sauna heater

Mount or set your sauna heater per the manufacturer's installation guide. While some obsess over venting, it's important to remember that you only need cooler air than your sauna. Thus, even 100 degrees is fine. Outdoor air is fine, but not necessary. Two vents are optimal but one behind the heater is fine. Some even use a wide gap under the sauna door.

All sauna heaters come with instructions and a template describing how high above the floor your sauna heater needs to be off the floor. Also, make sure you plan for some mounting brackets in the wall and a vent under the sauna heater. Consider space for a sauna heater guard rail, if you plan for a lot of foot traffic, or if the sauna heater is too near the door, a guard rail will prevent any burns, or accidents.

How to Build a Sauna: Adding Rocks to the Sauna Heater

We recommend that you wash your sauna heater rocks before placing the rocks inside. There may be dust on them which when burned can create an unpleasant smell. If your rocks are washed and clean, you are ready to put the rocks in. It's important to place your sauna rocks behind the heater element, else the sauna's sensors may falsely indicate the sauna room has reached the set temperature prematurely.

We often get asked, Is it OK to have the vulcanite sauna rocks in direct contact with the sauna heater element? And yes you do, by design.

While you want a good amount of rocks placed around the heater element. Do know place them too tightly as in a puzzle. Too much heat kept in the sauna heater can also set of a premature signal to the sauna heater telling the unit it is hotter than it actually is.

The sauna rocks are ideal for the sauna experience. They give off radiant heat which is the longer low level wave that penetrates the body, and feels like soft permeating heat. Finally set your rocks on top but test that your sauna heater's grill still fits on top.

Run your heater for a good hour with your sauna door open before your first use because of the preservative on the elements. These can create a bit of smoke when heated. Finally, secure the sauna heater's grill to the top of the unit.

Installing our sauna supports and benches

How to Build a Sauna: Set Your Sauna Benches

Next, build or assemble your sauna benches. Generally, there is a low bench and high bench. Some make the low bench double wide, so it reaches the wall.

If building your own, sauna benches are usually 18" or deeper. While it's always better to make your benches stronger than you'll need, you can get buy with 2x2 supports and 1x4 tops (where you sit).

Some sauna bathers and designers enjoy adding lights under the sauna benches. If you add the facing to the sauna bench, it shines a wonderful ambient light onto the surrounding sauna walls and floors, lighting your walkway.

How to Build a Sauna: Install Sauna Door

Install a pre-built pre-hung cedar sauna door. You'll be glad you did. These come with a frame and the swing is already set. We build cedar sauna doors with windows of all sizes, and etched glass. View sample sauna doors.

The standard rough opening for our factory door is 24"x82" RO (rough opening). This seems a little narrow to some, but the idea with a sauna is a small sauna door keeps the heat in.

Hanging the sauna door, handles and setting the self-closing hinges

The rough opening here requires some shim strips to square our door. Get a helper to hold your sauna door and frame in place while you screw in the frame. We like to use the 2.5" galvanized deck screws to mount the sauna door. The same ones we use for the sauna benches. Of course, place the screws where the closed door hides them.

Put in 2 screws to hold the door in place and test it by opening and closing the door. Make sure your reveal is correct. The reveal here means a making the frame flush with your outer wall so your molding closes all gaps.

Once you get the door jamb with hinges set, check your reveal on the top and the sides. You can fill any gaps with shims and screw the rest of the door tight.

Once the door is hung and plumb, you can put your handle on at comfortable height for you. I usually place it about 2 inches from the side.

With our sauna doors, we also include the self-closing bomber hinges with hinge pins and a hinge pin tool. The hinge pins help wind the door so it closes by itself — keeping your sauna just a lil hotter. The bomber hinge has holes which allow you to load up hinge tighter. See the FAQ and diagram: How to install the self-closing "bomber" hinge for the sauna door?

Cedarbrook offer many door options, by the way. See our residential sauna doors, commercial sauna doors, and custom sauna door options.

How to Build a Sauna: Finish with Trim

Attaching the interior trim to cover corner seams

Last, add the trim to the sauna corners. Some prefer not to add corner trim. If your corner seams look good, then just leave as is. You can make that choice at home.

We provide a packet of 1"x1" corner trim pieces. Choose the best face of the board and nail them down with your finish trim nailer. Be careful that your compressor is not set too high, 80 lbs is probably about right. Or if you have a small hammer, you can do it by hand too.

You may consider supplementing the angle of your comfort with a sauna head rest, leg rest or a back rest, as well as other accessories for the sauna bathing enthusiast.

We also offer cedar sauna grab rails to steady yourself when getting up or down off a high bench, and it never hurts to have a little extra help if floors get slippery.

And don't forget to attach the sauna door handle.

And before you turn your heater on consider our array of sauna accessories: sauna wool hats, sauna heater humidifier, and much more.

How to Build a Sauna: Add Your Cedar Duckboard (Flooring Panel)

Assemble the duckboard for the sauna walkway

You'll really appreciate touching cedar everywhere in the sauna including the floor. This video demonstrates how to assemble our sauna flooring kit. These kits are designed to be removed when needed for sweeping or mopping. Many only add duckboard to the entry way, but you can also add cedar to entire floor. If so, we recommend the floor still be easily removable. Either way, you'll love the smell of cedar in a warm sauna room.

ENJOY! There are some good sauna accessories to help you relax, such as head and leg rests, duckboard (flooring for the walkway), salt lamps, thermometers, hygrometers (to measure humidity), venik (to brush the body) ... enjoy!

Also read Home Sauna Room Advantages — Reviews the advantages of having a sauna in your home, such as cost, comfort, privacy, and convenience.

If we can be of more help, please email us or call us at 1.800.426.3929 or read on. Thanks!


Cedarbrook Sauna + Steam

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