My Pallet Sauna

The idea had been lingering in my mind for a long time, and one day I finally took the plunge: I was going to build a sauna in my garden. 🙂

For french people you can take a look at my site : https://diysauna.wordpress.com

Here are the various tools used during the construction (not much is needed):

• Miter saw
• Drill/Driver
• Jigsaw
• Crowbar
• Pallet Buster

The most important tool to have is a 'pallet buster': it allows for leverage and 'fairly easy' board removal. Mine was made from an old fork and 3 mason's chisels welded together.

Note regarding the ground surface: In France, it's important not to exceed 5m², otherwise, a building permit is required! That's why I chose the dimensions 2m x 2.50m.

• The red crosses symbolize the vents at the top => closed when the stove is heating and open when the session is over.
• The yellow crosses symbolize the vents at the bottom => one opening behind the stove for draft and one under the bench for extracting stale air.

Plans created using draw.io

This is the part you can't afford to mess up: everything needs to be perfectly square!

Three layers:

• Concrete blocks
• Pallets
• OSB panels

I used metal brackets to fix the rafters to the ground.

The rafters were recovered from an old terrace!

I wrapped the entire structure with a water-resistant membrane and screwed all the larger boards vertically.

The roof is made of corrugated metal sheets with panels measuring 91cm x 120cm, but I had miscalculated and the sheets barely protrude from the roof 😦

Very easy:

• 1 layer of glass wool insulation
• 1 layer of aluminum foil
• 1 layer of boards

For the ceiling, I used leftover 10cm thick polystyrene pieces.

In the photos, I initially planned to have the exhaust pipe exit from the top, but eventually, I decided to have it come out directly behind the stove to avoid multiple bends.

I fabricated a box to protect the wood around the exhaust duct as it passes through the wall: 2 riveted metal boxes filled with rock wool insulation. It's crucial to be careful because the pipes get extremely hot!

So far, the sauna hasn't caught fire, so this stuff is approved 😉.

I installed a gutter to collect rainwater and store it in the water collector.

This allows for refreshing oneself after leaving the sauna.

• 2 vents at the top
• 2 vents at the bottom.

The bench was also made from pallets, and all the boards were sanded.

I oiled all the bench boards with linseed oil to protect them.

To secure the windows, I used wooden strips.

Attention! Sufficient space should be provided for the window to be movable. I tightened it too much, unfortunately, the glass cracked because wood expands and contracts significantly with the seasons :'(

Stove

There was no doubt in my mind: I needed a wood-burning stove, not an electric one! The ritual of preparing the fire and the pleasure of watching the flames, it's priceless. 🙂

At first, I tried installing an old cast iron stove, but it wasn't efficient enough: those stoves are designed to store heat and release it slowly. Sauna stoves, on the other hand, heat up very quickly! So, I recommend going straight for a sauna stove.

• Model: Harvia M3 + stones (€520 delivered from Amazon)
• Weight: 45 kg
• Power: 13.5 kW
• Observed heating time: between 45 minutes and 60 minutes for 9m³ (depending on the outside temperature)

I use the “reverse lighting” technique which positions the large logs at the bottom and the kindling on top. I use a fire starter and wait carefully for 45 minutes, always leaving the ash drawer slightly open to get a good draft. There is no smoke in the sauna.

Thermometer

I installed this Inkbird ITH-20R thermometer with a probe positioned high in the sauna and the module outside. The receiver is located 10m away in the house: this way, I can turn on the stove and control the temperature remotely.

I don't think the temperature is exact, but the main thing is to know when the sauna is hot (>90°C)