Work out what an outdoor sauna build will cost before you buy a kit or hire a builder. Enter the sauna size, wood type, heater and labour choice to see the total build cost, the cost breakdown and the cost per square foot.
Formula: total build cost = materials + labour. Materials = panel cost + structure or kit cost + heater + foundation + electrical + extras. Labour is 45 percent of materials when you hire a builder and $0 when you build it yourself.
Enter the sauna size and a few build choices, and the calculator adds up the materials, the heater, the foundation and electrical work, and labour if you hire a builder. You get a total build cost, a breakdown and a cost per square foot.
Total build cost = materials + labour. Materials = panel cost + structure or kit cost + heater + foundation + electrical + extras. Labour is 45 percent of materials when you hire a builder, and $0 when you build it yourself.
Floor area = length x width, and room volume = length x width x height. Panel area, which covers the walls and the ceiling, = 2 x (length + width) x height + length x width, and panel cost = panel area x wood rate x (1 + waste percent / 100). Wood rates are cedar $6.00, hemlock $4.50 and pine $3.50 per square foot, the midpoints of the ranges published by Tahoe Sauna Company.
For a custom build, the structure line covers framing, insulation, a vapor barrier, exterior sheathing, roofing and the floor at $28 per square foot of floor area. For a kit build, the kit shell costs $70 per square foot of floor area and includes the shell, paneling, benches and door. The heater is sized at 1 kW per 45 cubic feet, rounded up and kept between 4 and 12 kW. An electric heater costs $200 plus $170 per kW, and a wood-fired heater costs $700 plus $110 per kW. The foundation allowance is $500, the circuit is $1,200 for an electric heater and $0 for a wood-fired heater, and extras are $450 for a custom build and $250 for a kit. Our concrete calculator prices a poured slab if you choose one instead of a gravel pad.
A homeowner plans an 8 by 6 foot outdoor sauna with a 7 foot ceiling, cedar paneling, a custom build, an electric heater, 10 percent waste and hired labour.
As a second check, the same sauna built yourself costs $6,664.40, or $138.84 per sq ft, and with a wood-fired heater the hired total falls to $7,952.38. The same steps work for any size, so try your own numbers in the tool above.
Labour is the biggest lever. Hiring a builder adds 45 percent of the materials cost, which is $2,998.98 on the worked example.
Size matters in a surprising way. The heater, the circuit and the foundation cost almost the same whether the sauna is small or large, so a small sauna costs far more per square foot. A 4 by 4 foot sauna built yourself costs $4,322.80, which is $270.18 per sq ft, while a 10 by 8 foot sauna with hired labour costs $13,135.26, which is $164.19 per sq ft.
Wood choice and waste move the total by hundreds of dollars. Pine instead of cedar saves $972.95 on the worked example total. With no waste allowance the total is $9,451.10, and with 15 percent waste it is $9,769.52.
A kit arrives as pre-cut panels or staves with benches, a door and hardware included, and most kits are designed for two people to assemble in a day or two. For the worked example size, a kit built yourself costs $6,870, against $6,664.40 for a custom build done yourself. The kit costs a little more, and it saves design and cutting time.
A custom build starts from raw lumber, so you choose the exact footprint, ceiling height, bench layout and wood. It suits an odd-shaped yard, a changing room, or a sauna that must match the house. It needs more skill, because you frame the walls, fit the vapor barrier, hang the door and build the benches yourself or pay a builder for each step. Kits usually cost $3,500 to $8,000 for four to six people before the pad, circuit and assembly, while a custom build runs $8,000 to $28,000. Our fence cost calculator prices the screening many outdoor saunas need.
Sort out the base and the power before you order anything. The sauna needs a level, well-drained base that keeps the timber off wet ground. A gravel pad costs about $200 to $800 and a poured slab about $800 to $2,500.
An electric heater needs its own dedicated 240V circuit, and the cost depends on the distance from the panel. A short run costs about $700 to $1,200 and a long trenched run $2,200 to $3,500. The calculator uses $1,200, the middle of the medium range. Only a licensed electrician should make the final connection, and the work usually needs a permit and an inspection. A wood-fired heater avoids the circuit entirely, but it needs a chimney and a dry store for firewood.
Finally, check the structure rules with your local building department. The electrical work usually needs a permit, and the structure may or may not, depending on its size and local rules for accessory buildings.
A typical kit-based outdoor sauna costs $5,500 to $14,500 installed, and a custom build costs $8,000 to $28,000. In the worked example, an 8 by 6 foot cedar sauna built custom with an electric heater and hired labour costs $9,663.38 in total, or $201.32 per sq ft. The same sauna built yourself costs $6,664.40.
Size the heater to the room volume, at about 1 kW per 45 cubic feet. The worked example sauna is 8 by 6 by 7 feet, which is 336 cubic feet, so it needs an 8 kW heater. A heater that is too small will not reach temperature, and one that is too large wastes energy.
It is usually cheaper to build, because it needs no dedicated 240V circuit. In the worked example, switching to a wood-fired heater removes the $1,200 electrical line and changes the heater cost, so the total falls from $9,663.38 to $7,952.38, a saving of $1,711. You will need a chimney and a supply of firewood instead.
For the same size they are close. In the worked example size, a kit build done yourself costs $6,870 and a custom build done yourself costs $6,664.40. A kit saves design and cutting time, while a custom build lets you choose the exact size, layout and wood.
In the worked example, cedar paneling costs $1,610.40 and pine paneling costs $939.40, so cedar adds $671 to the materials. With labour at 45 percent of materials, the total with cedar is $9,663.38 and with pine it is $8,690.43, a difference of $972.95. Cedar resists moisture and smells better, which is why most builders choose it.
The electrical work usually needs a permit and an inspection, and the electrician must make the final connection. The structure itself may or may not need one, depending on its size and your local rules for accessory buildings. Check with your local building department before you order materials.
This is an estimate for planning. Actual prices vary by supplier, location, permits and site conditions.
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