Barrel saunas have become one of the most popular ways to add a sauna to a backyard. Their round shape is efficient to heat, they are relatively compact, and many models arrive as kits that can be assembled in a weekend. Before you choose one, it helps to understand how wood, size, heater type and site preparation affect the experience. This guide covers the key decisions.
Why the barrel shape?
A barrel sauna is a cylinder of staves held together with steel bands and closed at each end with a wall. The shape offers a few practical advantages:
- Less air to heat. The curved ceiling removes the upper corners found in a square room, so a barrel has less interior volume than a rectangular sauna with the same footprint.
- Air circulation. Hot air rises and follows the curve of the ceiling, which helps distribute heat around the room.
- Structure. The staves and bands form a self-supporting shell, so there are no separate wall studs or roof framing.
The trade-off is less headroom near the sides and a fixed layout. Benches typically run along the length of the barrel, facing each other.
Choosing a size
Barrel saunas are usually described by interior diameter and length. Diameters of around 5 to 7 feet are common, with lengths from about 4 feet for compact models to 8 feet or more for family-size units. Many larger barrels include a separate changing area or a covered porch at the entry end.
Think about:
- How many people will use the sauna at once, and whether anyone wants to lie down on a bench.
- Bench length. Benches run along the barrel, so length determines how many people can sit comfortably.
- Changing room or porch. In cold climates a small changing area keeps the hot room closed while people get ready.
Calculating volume for the heater
Heater size depends on the interior volume of the hot room. For a cylinder, use π × radius² × length, measuring the hot room only (not a porch or changing room). A few examples:
- 6 ft diameter (3 ft radius) × 6 ft long: 3.14 × 9 × 6 ≈ 170 cubic feet
- 6 ft diameter × 8 ft long: ≈ 226 cubic feet
- 7 ft diameter (3.5 ft radius) × 8 ft long: 3.14 × 12.25 × 8 ≈ 308 cubic feet
Outdoor barrels lose more heat than indoor rooms, especially in winter, and glass end walls or panoramic windows add to that. Many buyers choose a heater in the middle or upper part of its rated range for an outdoor barrel. Compare ratings in our sauna heaters collection, and see our guide to sizing a sauna heater by room cubic feet for more detail.
Heater types for barrel saunas
Electric
Electric heaters are the most common choice. They are simple to control, can include timers and remote control boxes, and need no chimney. An outdoor barrel needs a dedicated circuit run from your panel, sized for the heater's current draw, and installed by a licensed electrician. Check whether your home has 208V or 240V service before ordering, since heaters are built for a specific voltage.
Wood-burning
Wood-fired heaters offer a traditional experience and do not require electrical service, but they need a chimney with proper clearances, a heat shield where specified, and more attention during use.
Gas
Gas heaters are less common in small barrels but are an option where natural gas or propane is available. For example, the Scandia 40K BTU natural gas sauna heater is rated for rooms up to 616 cubic feet. Gas heaters require venting and must be installed by a licensed HVAC professional. Confirm with both the sauna and heater manufacturers that the combination and venting arrangement are approved for your barrel.
Whatever heater you choose, install a heater guard where the manufacturer calls for one, such as a sauna heater guard rail, to keep bathers from contacting the heater.
Wood species and grades
- Western red cedar is the most common barrel wood. It is naturally resistant to rot, dimensionally stable, and has a distinctive aroma.
- Clear cedar has few or no knots and a uniform look. It generally has fewer surface checks and resin pockets.
- Knotty cedar has a rustic look with visible knots. It is structurally sound for saunas, though knots can occasionally loosen or show resin over time.
- Spruce and thermally modified woods are also used by some manufacturers and offer different looks and weathering behavior.
Stave thickness matters too. Thicker staves add insulation and rigidity, which helps in colder climates.
Preparing the site
A barrel needs a flat, level, well-drained base. Common options include a poured concrete pad, compacted gravel with pavers, or a sturdy deck. Most barrels sit on cradles that lift the shell off the ground so air can circulate underneath. Check local requirements for permits, setbacks and electrical inspections before you build.
Plan the path from the house, lighting, and where the electrical run or gas line will enter. If you live where heavy snow is common, consider how the roof will shed snow and whether you want a roofing cover such as shingles or a membrane over the staves.
Living with a barrel sauna
- Bands: wood expands and contracts with humidity and seasons. Check the steel bands periodically and adjust tension as the manufacturer recommends.
- Exterior finish: outdoor wood weathers to a silver-gray if left untreated. An exterior wood finish slows weathering. Interior wood is normally left unfinished, though bench oils made for saunas are available.
- Drying out: leave the door or vent open after sessions so the interior dries.
- Accessories: a bucket and ladle, a thermometer, headrests and fresh stones round out the room. Browse our sauna accessories, including natural sauna rocks.
A buying checklist
- Decide how many people will use it and whether you want a changing room or porch.
- Choose wood species and grade based on look and climate.
- Calculate hot-room volume and pick a heater with a comfortable rating margin.
- Confirm electrical service (voltage, phase and panel capacity) or gas supply.
- Prepare a level, well-drained foundation and check local permit rules.
- Plan for licensed installation of the heater and any electrical or gas work.
Have questions about heater sizing for a specific barrel? Send us the interior diameter, length and your location, and we will help you compare heater options.