Essentials for creating an authentic Finnish sauna at home – Finnmark Sauna

In Finland, sauna regulations form the backbone of the unique experience, quality, and longevity that makes Finnish saunas so impressive. Unfortunately, in the UK sauna regulations are almost non-existent. This means that any company can market their products as ‘traditional Finnish saunas’ without actually adhering to any of the guidelines. The best way to ensure you are getting an authentic Finnish sauna is to only use certified Finnish materials and adhere to Finnish sauna regulations.

Robbie Thompson at UK specialists Finnmark Sauna told us, “We specialise in indoor and outdoor bespoke installations and regularly build new garden building saunas and install into spare rooms and loft spaces. We also offer advice and materials to people who are taking on their own self-build projects. The key areas to concentrate on are the heater, battening, cladding, insulation, safety considerations, timber, vapour sealing, and finally ventilation.”

Sauna insulation helps the sauna heat up more quickly, and it protects the surrounding building from the sauna’s heat. There are two ways to insulate a sauna: fill the stud work with rockwool and cover this with aluminium sheets to vapour seal or use specially designed foil-backed insulation board.

Vapour sealing is the primary barrier standing between the warm, wet air trying to escape the sauna and any wood beyond it at risk from mildew, mould, and rot. Foil backed Kingspan Sauna Satu polyisocyanurate (PIR) insulation board which works as both an insulator and vapour seal and will not break-down over time.

Sauna battening, or counter battening as it is also known has the dual purpose of creating 

 a ventilation gap and allowing the drainage of condensation. The battens are long slim planks of wood which sit perpendicularly against the saunas cladding, They separate it from the insulation and vapour barrier.

Ventilation maintains a continuous source of fresh air into the sauna ensuring the hot air is well circulated. It also removes used air from the sauna before it becomes stagnant and ensures volatile or organic compounds entering the sauna air will be dispelled swiftly. Without it the sauna air becomes stale and potentially unhygienic. It can quickly deteriorate, become rotten and mouldy. A  

 proper sauna ventilation system has at least three vents. One under the heater to allow fresh air channels to enter the sauna (this can be supported or perhaps even replaced by leaving a gap under the sauna door if it is in close enough proximity to where the heater is placed). One under the sauna bench around 400mm from floor level – it helps bring the heat down and prevent the stratification of hot air towards the ceiling.

Finnish sauna standards also state that cladding must be at least 14mm thick to ensure durability in the sauna environment. It’s because the heat and moisture of the