Sauna Design Guide

Sauna Design

Aqua Spazio understand that building a high-quality sauna involves a combination of traditional Finnish principles and modern safety best practices. Proper design ensures safety, energy efficiency, and an authentic, enjoyable experience with good heat distribution and ample steam, known as löyly.

Our key factors while designing and building a sauna are

Location and layout

• Near a cooling area: Where possible, locate the sauna near a shower, pool, or a private outdoor space for the essential hot-and-cold therapy cycle.

• Outward-swinging door: The sauna door must open outward for safety. If a person collapses, they will not block the exit. Magnetic or gravity closures are preferable to a lock. A small gap at the bottom of the door can serve as a fresh air intake.

• Multi-tiered benches: For an optimal temperature gradient, install at least two bench levels. Since heat rises, the top bench is the hottest, giving bathers a choice of temperature.

  • Ceiling height: We keep a maximum ceiling height of 2100mm that is recommended to keep the hottest air within the bathing area.

  • Bench heights: Standard recommendations are for the upper bench to be about 900mm from the floor, the lower bench 450mm, or a step at 450mm if we don't have enough space to put a bottom bench.

  • Bench placement: Ensure the top benches are about 1,000mm from the ceiling to keep bathers in the thermal layer. Also, this allows enough space for users to lie down comfortably. 

Materials

• Framing: We construct the frame with sturdy, dry treated lumber. For benches and interior cladding, use high-quality, knot-free softwoods like Western Red Cedar, Aspen, or thermally treated woods. These materials resist moisture, warping, and do not get uncomfortably hot. Avoid resinous woods like pine.

• Vapour barrier: An aluminium foil vapour barrier is critical to prevent moisture from penetrating the wall structure, which can cause mould and rot. It also reflects radiant heat back into the room. It should be taped at all joints to create a continuous seal.

• Insulation: Insulate the walls and ceiling with mineral wool or sauna-specific PIR insulation boards rated for high temperatures. Standard fiberglass can off-gas at high temperatures, and standard PIR insulation can produce toxic gas above 60°C. A well-insulated sauna heats faster and is more energy-efficient.

• Flooring: Tile or concrete floors with a drain are recommended for easy cleaning and handling moisture. Avoid wood floors, which can absorb perspiration and rot. Removable wooden duckboards can be used over the floor for comfort. 

Heating and ventilation

• Ventilation is key: Proper ventilation circulates fresh air, removes stale air, and prevents mold. Poor ventilation leads to a stuffy feeling, nausea, and potentially hazardous air quality.

• Passive ventilation: The traditional Finnish method uses two passive vents. An intake vent is placed low, near the heater, and an exhaust vent is placed high on the opposite wall to use the natural "chimney effect" of rising heat.

• Active ventilation: For commercial or sealed spaces, a mechanical system with an exhaust fan can be used. In this system, intake air is often introduced above the heater, with the exhaust drawn from under the benches.

• Sauna heater: The heater must be properly sized for the room's volume, including adjustments for any glass panels, which lose heat faster. An under- or oversized heater will result in an inefficient, uncomfortable experience.

  • Electric vs. wood-burning: Electric heaters are common and easy to install in a home. Wood-burning stoves offer a traditional, ambient experience but require a flue and proper fire safety measures.

• Löyly (steam): The best heaters have a high stone capacity. Large, volcanic stones are best for absorbing heat and producing a soft, substantial burst of steam when water is thrown on them. More stones result in better steam. 

Safety and details

• Electrical safety: All electrical work should be performed by a qualified electrician and must adhere to local building codes. Use heat-resistant, moisture-proof wiring and light fixtures.

• Clearance: Maintain the minimum safety distances between the heater and benches or combustible materials, as specified by the manufacturer. Heat shielding may be necessary in tight installations.

• Accessories: A thermometer and hygrometer are essential for monitoring the room's conditions. A bucket and ladle for water and non-metallic, heat-resistant handles for the door and accessories are also critical.

• Maintenance: Treat the wood with paraffin oil yearly to protect it from heat and moisture. Clean benches regularly to prevent stains and dirt.