Premium Sauna Insulation & Vapour Sealing Solutions

Insulation thickness depends on your build and the materials selected. Specialist sauna insulation boards, such as Kingspan Sauna-Satu or Finnfoam, are typically around 30mm thick, while the full wall build-up may reach 70-80mm once the insulation, vapour barrier, and cladding are installed. The goal is to achieve strong heat retention while also ensuring the structure remains breathable and safe. Our sauna specialists can advise on the ideal thickness for your project.

The best sauna insulation for walls and ceilings must balance thermal resistance, moisture protection, and long-term reliability. Options include traditional mineral wool with an aluminium vapour barrier or modern foil-backed insulation boards such as Kingspan Sauna-Satu or Finnfoam PIR, which combine high thermal conductivity with built-in vapour sealing in one product. Unlike standard PIR boards, which are not suitable for saunas, these specialist solutions are engineered to withstand high temperatures safely, without releasing harmful chemicals such as hydrogen cyanide.

Corners, joints, and penetrations are common weak spots in a sauna’s vapour barrier. To ensure complete protection, these areas should be carefully sealed with aluminium vapour barrier tape, maintaining a continuous moisture barrier across the entire structure. Where larger or irregular gaps occur (such as around pipework), specialist expanding foam designed for sauna construction can be used first to fill the voids, before taping over to finish the seal. This prevents warm, humid air from escaping and protects surrounding materials from damage.

Yes. A sauna vapour barrier is essential to prevent warm, humid air from seeping into surrounding timber, which can cause mould, mildew, and rot. Aluminium foil vapour barriers or foil-faced boards provide a continuous moisture barrier, protecting your sauna structure and ensuring decades of reliable use.

No. Standard insulation materials are not designed to withstand the intense heat, humidity, and moisture levels of a sauna. More importantly, they may also present safety risks when exposed to high temperatures and potentially release harmful chemicals, such as hydrogen cyanide, into the sauna. Specialist insulation for sauna construction is engineered to resist heat, provide reliable vapour sealing, and ensure both long-term efficiency and safety, giving you complete peace of mind.

Yes. Proper sauna insulation reduces thermal conductivity losses, helping your sauna heat up more quickly. It ensures that heat is retained within the room, creating an efficient, consistent environment while reducing strain on your heater. Insulation also improves soundproofing within the space. Well-planned and properly installed sauna insulation enhances overall energy efficiency and ensures every session feels consistently comfortable and indulgent.