Sauna Dimensions & Sizes

What dimensions should a new sauna ideally have? To minimize heat loss, standard ceiling height is 7 feet. Typical room sizes are from 4 by 4 feet to 8 by 12 feet.

When planning a sauna’s size, figure you’ll need at least 2 feet of bench space for each bather; ideally, bathers should be able to recline, so, if possible, allow 6 feet in one direction.

Be aware that the size dictates not only how many people can comfortably sauna at a given time but also the output capacity of the heater you’ll need.

Most saunas have benches at two heights, an upper bench, about 36 inches high, and a lower bench, about 18 inches high. Upper-bench widths are typically 18 to 24 inches.

The lower bench has three functions: it serves as a step, provides a footrest when one is seated on the upper bench, and offers a significantly lower temperature zone for when the upper-bench area feels too hot.

Some manufacturers make a sliding lower bench that eases cleaning. Most saunas have removable duckboard flooring; some offer flooring that is made of flexible, web-like polymer sections that simply snap together.

Some saunas have windows; many have a glazed door that provides an open feeling. Glass may be clear, opaque or even etched with a design. But remember: the more windows, the greater the heat loss. Choose energy-saving glazing that has a 1/2- to 1-inch air space between the two outer layers of tempered safety glass.


All woods need to be kiln dried to about a 10% moisture content to prevent warping. All sauna woods should be non out gassing. Knotty wood is unacceptable, as it leads to cracking and splitting.

  • Aspen: Soft, light and low in strength and stiffness. Poor decay and shock resistance. Dents and scratches easily.
  • Basswood: Also know as linden. Soft, light, low in strength . Popular among hobbyists for model building and wood carving. Too soft for long term durability.
  • Fir, White: Light, soft, moderately stiff. Low strength and shock resistance. Poor decay resistance. Some saunas that fir produce a distinct odor.
  • Pacific Coast Hemlock: Very stable with little tendency to cup, check or twist. It yields clean, straight edges and accurate contours. The combination of stability and smoothness has made Hemlock a favorite wood for the construction of saunas. An excellent choice if you have allergies, as it has very low resin and no odor.
  • Western Pine: Moderately stiff, low strength and shock resistance. Soft, light and good stability in service. Not normally recommended for saunas as it has a high resin content and is subject to out gassing, which can irritate eyes and nasal membranes. Knots are common.
  • Sitka (Spruce): Moderately low in strength, but very high strength to weight ratio. Light and soft with low decay resistance. Non out gassing, but prone to excessive knots. Rough exterior. Some splitting and cracks are common.
  • Poplar: A non out gassing wood, but most species are typically soft and light with low ratings for strength, stiffness, decay resistance and durability. Moderate movement in service. Not as stable as some woods under hot/cold conditions.
  • Canadian/ Western Red Cedar: Renowned for its natural beauty and outstanding physical properties that make it one of the world’s most unique species. Low shrinkage factor and superior to all other coniferous woods in its resistance to warping, twisting and checking. With its low density and high proportion of air spaces, Canadian Cedar is the best thermal insulator among the commonly used woods for saunas. Excellent durability. Non out gassing when properly kiln dried and treated. A bit more costly than Hemlock.
  • California Redwood: Generally straight grained with a medium rough texture. A light and soft wood with moderate stiffness, very good decay resistance and good stability in service. Generally too expensive to enjoy widespread use in saunas.
    Note: the ceiling height for a sauna can be from 6 1/2 to a maximum 7 feet high. Because heat rises, you want the benefit of the warmer air in the sauna while you are laying on the upper bench, so a ceiling height of 8 or 9 feet is going to defeat this, plus your heater will not function properly.

Saunas can be virtually any size or shape.

Hint: If you enjoy lying down in your sauna, allow 6 feet in at least one direction.

Plan the location of your heater, preferably near the door wall. Remember that cool air will be naturally drawn from the door, along the floor to the heater where it will be heated and naturally rise to the ceiling.

Plan the bench layout: normal sauna bench depth is usually 19"; height is either 38" ( for the upper bench) or 19" high (for the lower bench).

Hint: You will either sit or lie down in your sauna so include maximum benching as space permid note that the upper bench will be the warmer bench.

You want to use aluminum foil vapor barrier, NOT polyethylene


In most residential situations, a drain is not necessary. If water is pooling on the floor you are using too much water! Some plan on installing a drain in commercial saunas if the sauna is going to be washed down often.

Door Opening: (refer to the sauna door page for more information)

Sauna doors are usually smaller than normal residential doors. This is intentional to preserve as much heat in the sauna as possible when people enter or leave the room. Insulated doors usually measure 24" x 76" o.s.m. plus the cedar frame. This requires a 26" x 78" rough opening for your door. Custom size doors are usually available if needed.

Sauna doors (without window glass) are often supplied with an adjustable exhaust vent in the upper portion of the door.


Proper venting is necessary for fresh oxygen and to create air flow for efficient operation of your heater. Fresh air can be supplied through a) a non-adjustable vent installed in the wall under the heater position, or b) by leaving an air space (up to 1") between the threshold and the bottom of the door panel.

An adjustable exhaust wall vent on the opposite wall to the incoming air allows air to circulate and distributes the heat more evenly throughout the room. Any exhaust wall vent should have sliding doors controlling the volume of air allowed into the room. The exhaust vent is normally installed 48" to 54" from the floor. See Heater installation instructions for correct location.

Locating your exhaust vent within arm's reach of the upper bench is good, this way you can adjust air circulation from the upper bench where you will spend most of your sauna time.


Sauna lights are specially certified for sauna use in high-heat, high-moisture environments. Do NOT use any conventional fixtures in your saunas.

Many saunas built today include a second or even a third sauna light. These additional light fixtures are usually mounted on the main bench wall, but about 3 inches below where the upper bench meets the wall. This way they are hidden from casual view, yet illuminate the traditionally dark area below the benching, plus they shine upwards through the slats in the benching creating a wonderful reflected lighting effect in the sauna.