When you build an outdoor sauna, a wood-burning stove is the best choice for long-lasting performance as a heat source. It is particularly good if the sauna is out in the country where firewood is prevalent. The stove adds to the natural appeal of a traditional sauna and your experience in it. Mikkel Aaland, author of "Sweat," the 1978 sauna history book, affirms that choosing a heater is the first decision to make in building a sauna and that wood-burning stoves "must be considered first choice."
Purchase an old gas bottle. An empty propane tank from a gas grill is ideal. Remove the valve from the top of the tank. Fill the tank with water and let it soak for one to two days to clean out any leftover gas.
Cut an opening across the top of the tank to hold the rock basin. Measure the space for a door, about 30 by 22.5 cm (12 by 9 inches), that will allow you to stoke the fire. Cut the door from the front of the tank. Reattach the door with metal hinges screwed into the side of the tank.
Cut another circular opening on the back side of the tank, just below the top opening. Here you will attach the ventilation flue pipe. Measure the diameter of your pipe tube and make the opening just big enough to fit the pipe inside it.
Slit the bottom of the flue pipe with 5 to 7.5 cm (2 to 3 inch) cuts to bend back the opening and create an attachment plane. Weld or screw the flue pipe to the stove. For ventilation, run it through the ceiling of the sauna or out the wall behind the stove. You need outside air to produce oxygen for the stove so it doesn't draw on oxygen in the sauna.
Secure a metal basin in the top opening for the rocks. Adjust the hole to make sure the rock basin fits tightly without letting gaps of air through. Paint the stove if you like.
Create a single-layer brick or concrete block wall around the stove to protect it from getting kicked accidentally. Mount a concrete slab within the wall for the stove to sit on. Attach fireproof wall and ceiling guards in the space around the stove and above it to prevent fires.
Test the stove and burn off any paint odours by building fires in it outside the sauna before finally installing the stove inside the sauna. Keep a fire extinguisher in the dressing room of the sauna in case of emergencies. Mind building regulations in your area for outdoor wood-burning stoves and have the stove inspected by the fire brigade before its first use.
Fireproof the ceiling of the sauna above the stove as well as the corner walls, surrounding it with cement particleboard or a similar fire-resistant substance. Never set a wood-burning stove directly on a wooden floor.