Building a Sauna Guide

A comprehensive roadmap to sauna building. Essential guide and tips for creating your own genuine sauna.

Important Guidance

• Consider it like a basic roadmap and use it as a foundation in building your sauna.

• Images included in this guide are intended solely for visual reference, do not rely on it for precise measurements. Please refrain from using them for scaling or dimensioning purposes.

• Ensure that local electrical codes and standards are followed.

• Ensure that there is proper insulation and vapor barrier standards are followed.

Location Preparation Indoor or Outdoor

• Try or measure the sauna benches in the space before diving into the actual work. This ensures they completely fit inside the sauna once all the wall components are in place.
• Verify that the walls and lowered ceiling are constructed according to specifications.
• Double-check the heater power cable to make sure it's the right one, in the right spot for connecting.
• Ensure the power cables are in the correct locations for connection.

Pre Sauna Installation

• Ensure that insulation is properly placed or installed.
• Proper vapor barrier standards are observed.
• Battens are installed for mounting the cladding boards (for walls) or supporting the benches.
• Ensure that the wiring plan is properly followed and observed.

Sauna Installation

Walls

Vapor Barrier - A properly sealed vapor barrier is essential in stick-built sauna construction. Despite the common misconception that saunas are "dry," they generate heat and steam, increasing pressure inside the sauna. This elevated pressure can push moisture against the walls and ceiling, leading to condensation in the insulation if not stopped by a robust vapor barrier. Wet insulation reduces effectiveness and creates a conducive environment for mold and rot.

Insulation - While energy efficiency is not as critical in saunas as in residential buildings, proper insulation is crucial for bather comfort. Inadequate insulation can exacerbate thermal stratification, making certain areas of the sauna feel colder than others. Well-insulated walls contribute to more even and comfortable heat distribution around the bather's body.

Effective Sealing - Proper ventilation in saunas requires sealing off unwanted air leaks. Uncontrolled air ingress compromises air quality and ventilation effectiveness, potentially leading to mold growth and structural damage from moisture infiltration.

Saunas Do Not Require Breathing - Preventing air infiltration through leaks is vital for maintaining air quality and ventilation efficiency. Moist sauna air penetrating wall cavities can degrade insulation, promote mold growth, and jeopardize structural integrity.

Air Gap Necessity (Between Insulation or Vapor Barrier to Wood Walls) - It's advisable to maintain an air gap between non-permeable surfaces and wood components in sauna construction. When using radiant foil or foil-faced PIR as a vapor barrier, incorporating an air gap—ideally between 0.5 to 0.75 inches—using furring strips is recommended. This gap serves several purposes: reducing thermal bridging, facilitating drying of wall boards to prevent mold, and allowing the radiant foil to function effectively by reflecting heat back into the sauna space.

Wall Construction Classifications

Best

• Exterior cladding with rain screen to protect against external elements
• Exterior mineral wool insulation provides thermal protection
• Studs for structural support and further insulation
• Foil-faced PIR (Polyisocyanurate) insulation layers contribute to thermal resistance
• Air gap
• Interior tongue-and-groove (T&G) paneling

Very Effective option 1

• Exterior cladding with rain screen to protect against external elements
• Studs for structural support and further insulation
• Foil-faced PIR (Polyisocyanurate) insulation layers contribute to thermal resistance
• Air gap
• Interior tongue-and-groove (T&G) paneling

Very Effective option 2

• Exterior cladding with rain screen to protect against external elements
• Exterior mineral wool insulation provides thermal protection
• Studs for structural support and further insulation
• Air gap
• Interior tongue-and-groove (T&G) paneling

Better

• Exterior cladding with rain screen to protect against external elements
• Studs for structural support and any type of insulation
• Air gap
• Interior tongue-and-groove (T&G) paneling

Good

• Exterior cladding to protect against external elements
• Foil wall insulation with no air gap
• Interior tongue-and-groove (T&G) paneling

Definition of Terms

PIR (Polyisocyanurate) insulation: Type of rigid foam insulation known for its excellent thermal performance and fire resistance.

Rain screen: Designed to shed bulk rainwater and/or condensation downward and outward in a manner that will prevent uncontrolled water penetration into the conditioned spaces of a building or structure.

Mineral wool insulation: Type of thermal insulation made from natural or synthetic minerals, primarily basalt, diabase, and slag.

Tongue-and-groove (T&G) paneling: Consists of boards with a tongue (a protruding ridge) along one edge and a groove (a channel) along the opposite edge. When installed, the tongue of one board fits into the groove of the adjacent board, creating a snug and seamless joint between the panels.

Floor