Sauna installation is three jobs that arrive as one quote: preparing the place it stands, getting power to it, and putting the cabin together. Only one of those is optional for a competent owner, and knowing which is which is how you avoid paying a premium for the easy part and skimping on the part that matters.
The base and the site
Outdoors this is a level, drained base that will carry the loaded weight and stay level: compacted gravel with pavers, a rated deck, or a small slab. Indoors it is a floor that tolerates heat and the odd splash, and a wall build-up with insulation and a sealed vapour barrier. Neither is glamorous and both decide whether the cabin is still square in five years.
The electrical, which is not yours
A traditional heater above the smallest sizes needs a dedicated circuit sized to its rating, run from the panel and installed by a licensed electrician to code. Many infrared cabins plug into an ordinary outlet, which is the main reason they dominate indoor sales. Get the electrical quoted before you choose the cabin, because it can change which cabin you can afford.
The assembly
A prefab or barrel kit is bolts and bands and a day with a second pair of hands. A precut room lining is carpentry: framing, insulation, vapour barrier, cladding, benches and trim. Installers charge for assembly, and it is the line most owners can remove from the quote if they are comfortable with tools and have somebody to help lift.
Permits and what to ask the quote to itemise
An outbuilding often needs a permit and a setback from the boundary, and a wood stove usually needs both plus your insurer's agreement. Ask any quote to separate base, electrical, assembly, heater and delivery. A single figure hides which part you could do yourself and makes two quotes impossible to compare.
Questions people ask about sauna installation
Can I install a sauna myself?
The base and the assembly, usually yes. The electrical for a traditional heater is a licensed job, and in most places so is the permit for an outbuilding or a solid fuel appliance.
What does an installer actually do?
Typically assembly and sometimes the base. The electrical is normally a separate licensed trade even when the installer arranges it.
What is the most commonly missed cost?
The circuit. A dedicated run from the panel for a traditional heater is not in the cabin price and is not optional.