DIY Wood Fire Sauna Build

Build your own DIY wood fire sauna! A step-by-step guide to creating a cozy, rustic retreat with natural cedar and efficient wood heating.

Small sauna with a wooden door, a small window to the left, and two log benches on either side. Firewood is stacked beneath the benches. The ground is lightly covered in snow, and bare tree branches are visible above.

There’s nothing quite like the warmth and relaxation of a wood-fired sauna. Martin has been wanting to build one in our backyard for years!

When we stumbled upon a free wood-burning stove on the side of the road last spring, we knew it was the perfect excuse to get started and build our own backyard retreat.

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A man with gray hair and a beard, wearing a plaid jacket, gray sweater, and jeans, stands in the doorway of a small wooden building. Snow is on the ground, and firewood is stacked beside the entrance.

TABLE OF CONTENTS

After some planning, a bit of time off this fall and a lot of hard work, we created a cozy cedar sauna. If you’re thinking about building one yourself, here’s a step-by-step guide to help you along the way.

A small wooden sauna with benches and a firewood stack on the floor. A black wood stove is in the corner, and a sign reading its getting hot in here is mounted on the wood-paneled wall.

DIY Wood Fire Sauna

Our sauna structure was made using mostly left over building supplies from our Carriage House build. This was the plan all along so it was nice knowing that we didn’t have to start from scratch.

The cedar for the door and interior cost roughly $1,500 with other supplies and materials being around $1,000. Leaving us with a total of only $2,500 for this 8’x6′ sauna build.

The free wood burning stove saved us over $2,000 alone! Let’s get right into how we did it…

A wooden door with a round decoration is set in a brown wall with white trim. Next to the door is a small wooden stand holding cut firewood. Snow is on the ground, and two hooks are mounted on the wall above the stand.

Materials List

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Wood-burning stove (FREE)
Heat-safe black spray paint
Double-wall chimney ($90 from Marketplace)
2x4s for framing
3/8” OSB for sheathing
Cement for flooring (approx. 1.5” thick)
R14 insulation (or higher)
Building paper or roof paper
Shingles (leftover from previous projects)
Hardi plank and smart trim for siding
Facia and soffit
Cedar tongue and groove planks
16-gauge brad nails
Cedar deck boards (5 1/4” wide) for benches
Corrugated metal (for stove protection)
Outer door handle
Inner door handle
Timer, thermometer, and closure hook for door
Black sauna bucket
Rope lighting
Wooden hooks and outdoor benches
Cedar head rest
Lava rocks
Felt sauna hat
Wooden sauna sign – etsy
Metal “it’s getting hot in here” sign – custom from RHENworks (@rhenworksmetal)

A metal wood-burning stove sits outside on grass, with a cardboard sign on top that reads FREE HEAVY in black marker. A fence and trees are visible in the background.

Instructions

1. Prepping the Stove

We found a free wood-burning stove and brought it home (with the help of the teenagers, of course).

A black wood-burning stove sits on a concrete surface with wooden boards as a backdrop. It has a glass front door and a coiled metal handle. A stack of dark plastic pots is visible on a wooden deck to the right.

Cleaned off rust and dirt, then spray-painted it with heat-safe black spray paint to restore its look.
Then we found and purchased a double-wall chimney for $90 on Marketplace.

A wooden platform or deck under construction in a backyard with trees and foliage surrounding it. Theres a gravel path leading to the platform, and a yellow-handled tool rests nearby. A mix of cloudy and sunny skies is visible above.

2. Building the Base and Structure

Next we created a 6’x8’ base with a step down to the deck.

Wooden frame of a small building under construction, with a partial roof. The structure is surrounded by leafy trees and a white fence. A power cord is visible on the ground, and building materials are scattered nearby.

Framed the walls using 2x4s.

A small structure under construction with OSB board walls and openings for a door and window. The frame is set on a wooden base, surrounded by tools and materials. Trees and a cloudy sky are visible in the background.

Sheeted the exterior walls with 3/8” OSB. Leaving space for a small window and a door at the front.
Designed a single slope roof for easy snow and rain drainage.

Interior view of a small sauna under construction, showing walls lined with insulation material between wooden studs. The ceiling is covered in oriented strand board (OSB). The floor is unfinished wood.

3. Insulation and Wrapping the Exterior

Used leftover insulation from our carriage house build to insulate the walls and ceiling (minimum R14 recommended).

Small wooden sauna under construction with a flat roof, covered in protective house wrap labeled Weathermate and Rigidstik. Surrounded by autumn trees with colorful leaves and situated beside a house with a visible chimney in the background.

Wrapped the exterior in building paper—we actually used leftover roof paper instead (building paper is cheaper!)

Person wearing jeans and a hat, standing on the roof of a small shed under construction. Tools and materials are on the roof. A ladder is leaning against the shed. Trees with red berries are in the background under an overcast sky.

4. Roofing and Siding

Our 16-year-old, Jude, installed the shingles on the roof using his experience from the carriage house build.
Meanwhile, Martin sided the sauna with Hardi plank and smart trim (also leftover materials).
We installed facia and soffit around the roofline.

Interior view of an unfinished wooden sauna under construction, featuring partially insulated walls with fiberglass and wooden paneling on the lower half. The floor is plywood, and the ceiling beams are visible.

5. Interior Cedar Finish

Next we purchased enough cedar to build a custom door, benches and create interior walls.

A person wearing a black hoodie with a graphic design holds a wooden door frame while smiling. The scene is outdoors, with woodworking tools and materials on a deck in the background.

A wooden door with prominent grain patterns and a black metal handle. The door is set within a wooden frame, matching the paneled wall surrounding it. Soft lighting highlights the natural wood texture.

Martin crafted a stunning cedar door—how? I don’t know, but it turned out beautifully!
He and the teenagers lined the interior walls with cedar tongue and groove planks using a 16-gauge brad nailer.

6. Pouring the Cement Floor

Poured a 1.5” thick cement floor inside the sauna.
Bonus: Our tiny chihuahua, Bokatan, left a paw print as a keepsake.

7. Installing the Stove

Once the flooring was dry, we hauled the 300+ lb wood stove into the sauna (a team effort, for sure!).

Interior view of a space with wood-paneled walls, featuring an L-shaped wooden workbench in progress. A white desk lamp is on the left, and tools like a drill and level are scattered on the workspace.

8. Bench Construction

Martin framed out the benches:
- Lower bench: 18” from the floor, 12” wide.
- Upper bench: 38” from the floor, 22” wide.
We used 5 1/4” cedar deck boards for the bench seats. Martin sanded everything so that it was smooth.

Wooden sauna interior with a bench along the right wall and wooden panels. Firewood is stacked on the floor beneath a small table. A heater is visible in the corner, and the door is partially open.

9. Final Touches

Installed a backrest along the upper bench.

A small black stove with a metal chimney is surrounded by wooden walls. Smooth black stones are arranged on top of the stove. Metal panels cover part of the walls beside the stove. The flooring is light-colored concrete.

Added protective corrugated metal around the stove.

Installed the stove pipe.
Trim around the door and window.

A cozy wooden sauna interior with a small corner bench. A clock hangs on the wall above, and a pair of wooden sandals rests on the bench. Soft lighting highlights the warm tones of the wood.

Added rope lighting under the benches for ambiance.

A stack of firewood neatly arranged under a simple wooden shelf attached to the corner of a house exterior. The wood is covered with a light layer of snow, and the ground around is dusted with snow.

Mounted wooden hooks and outdoor benches for robes and belongings.

A wooden wall-mounted homopolar clock with a vertical rod and a sliding metal pointer. Time markers are inscribed on both sides of the rod, surrounded by light-colored wood paneling.

Installed a timer, thermometer, closure hook for the door, and a fun sauna sign.

A wooden door with a rustic latch system. The door has a black metal handle, and a rope is used as a makeshift lock, tied between the handle and a wooden block on the frame. The wall and door have a natural wood finish.

Wooden sauna interior with a felt hat featuring horns on a bench. A black sauna bucket with a ladle rests beside a small container. The setting suggests a Scandinavian sauna with traditional themes.

A corner of a wooden sauna with smooth, natural wood paneling and benches. An abstract wooden sculpture rests on the top bench. The space is empty, warm, and inviting with soft lighting highlighting the wood grains.

Tips & Tricks

Use what you have – we saved a lot of money by using leftover materials from previous builds.
Go for a single-slope roof – it’s simple to construct and helps with snow and rain runoff.
Insulation is key – a minimum of R14 will help retain heat effectively.
Teamwork makes the dream work – having teenagers involved not only helped speed things up but also gave them useful construction experience.
Pre-plan ventilation – ensure proper airflow and chimney placement for safety.
Add fun details – the rope lighting and fun sign make the sauna feel extra cozy and personalized.

Small wooden sauna with a natural wood door, flanked by benches and stacks of firewood on each side. The structure is painted in beige with white trim. A few trees are in the background under a clear blue sky.

Now, our DIY wood-fired cedar sauna is the perfect backyard escape for relaxing after a long day. With the warmth of a wood burning stove and the rustic beauty of cedar, it’s a project we’re proud of!

One that will bring us warmth for years to come – after a long ski day or a busy day building the next project!

A small wood fire sauna with a light brown exterior and a wooden door invites warmth. Neatly stacked firewood flanks the entrance, while snow carpets the ground and trees stand nearby. Text overlay reads, DIY: How to build a wood fire sauna.

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Hello, I’m Heather!

I'm an active mom of twin boys who is always looking for opportunities to inspire creativity through fun crafts, do-it-yourself projects and delicious recipes. This blog has been an integral part of supporting my little family and I am so grateful to have you become a part of our journey! Let's create together... Read more...