Sauna Kits: What’s Included and What Isn’t

Open the crate and you will find the sauna you can see: tongue-and-groove cladding cut to your wall lengths, benches, a door, foil and tape, trim, fasteners, and in most packages the kiuas — the stone-topped sauna stove — with its controller and stones. That is real work you did not have to do; the milling, the cut list, and the door hardware arrive decided.

It is also, reliably, not a whole sauna. The three systems that determine whether the room works arrive in nobody’s crate, and all three have to be settled before the first board goes up.

What arrives in a sauna kit crate?

Component	In a typical interior kit	Notes
Wall and ceiling cladding	Yes, precut	Cut to the wall lengths you supplied
Benches	Yes — lumber, brackets, or assembled	Bench height is often fixed by the vendor
Door	Yes	Glass or wood; swings out by convention
Foil vapor barrier and tape	Usually	Enough for the surfaces they quoted, rarely more
Trim, corner moulding, fasteners	Usually	The fiddly parts, which is the point
Heater, controller, stones	In “with heater” packages	Sized to a nominal volume, not your room
Backrests, headrests, guard rail	Sometimes	Frequently a paid upgrade
Framing, insulation, wiring, floor, vents	No	See below

What do kits leave out, and what does that add?

Four things, near-universally. Treat these as mid-2026 planning ranges, not quotes — labor rates move them more than materials do.

Omission	Why it is excluded	Planning range
Dedicated 240 V circuit	Licensed, permitted, local	$500–$1,500
Floor and drainage	Depends entirely on your substrate	$150–$1,200
Ventilation openings	Depends on heater type and room shape	$50–$400 in parts
The room shell, for interior kits	You supply framing and insulation	$600–$2,000

A kit at the bottom of the $4,000–$9,000 band can therefore land near $6,000 installed, and the difference is not padding — it is the part of the sauna that makes it a sauna. The broader question of whether a kit is even the right path is worked through in the kit versus custom build comparison.

Why is the electrical work never in the box?

Because it is the one part of a sauna that is regulated by where you live rather than by what you bought. Finland’s safety authority, Tukes, sets out the logic clearly enough to borrow: installations follow SFS 6000-7-703, the zone within half a metre of the heater takes nothing but the heater, no receptacles or standalone switches belong inside the room at all, and ordinary cable must sit on the cold side of the insulation.

That last rule is the one that catches kit buyers. Cable on the cold side of the insulation is a decision made while the studs are still open — weeks before the crate is. In North American terms: a licensed electrician, a dedicated 240 V circuit sized to the heater, and an inspection, all scheduled ahead of the cladding.

What does the floor cost that the kit didn’t quote?

Whatever your substrate demands. Suomen Saunaseura’s structural guidance describes both traditions: a tongue-and-groove plank floor pitched toward a drain, or a modern waterproofed floor with sealed seams and a properly supported substrate. Either is fine. Neither ships flat-packed.

On a basement slab this can be a floor drain, a sealer, and a duckboard grate. Over a wood-framed floor it is a membrane, a pan, and a real decision about where water goes. Settle it during the planning pass, because the answer changes the finished floor height, which changes the bench heights, which the kit has already cut.

Where does ventilation get decided?

Before the cladding, and by the heater. The Finnish Sauna Society’s own members put it plainly — toimiva ilmanvaihto, siitä kaikki lähtee, functioning ventilation is where everything starts. A sauna needs an intake and an exhaust, and the correct placement depends on whether the room is on gravity or mechanical extraction.

Kits rarely include so much as a grille, which means the openings are yours to frame. Once the tongue-and-groove is on, cutting them is joinery instead of framing. Read the ventilation layout guide before the crate arrives, not after the first disappointing session.

Does the kit’s heater actually match your room?

Not automatically. Harvia’s own sizing calculator asks three questions beyond width, depth, and height: is the sauna built of log, is there a glass door, and how many square feet of wall are uninsulated. Its explanation is short: power requirement rises with window surfaces and heat-storing surfaces such as brick, concrete, or logs.

A kit heater is matched to a catalog cabin with insulated walls and a modest door. Swap in a full glass front, or set the kit inside an uninsulated garage bay, and the arithmetic changes. Run the numbers against heater sizing before accepting the bundled model.

What should I ask before ordering a kit?

Send the vendor these, in writing, and keep the reply:

1. What are the exact interior dimensions this kit is cut for, measured inside the finished cladding?
2. Is the heater sized for those dimensions with my door and wall construction, or for a nominal volume?
3. Does the package include foil and tape for the ceiling as well as the walls?
4. What bench heights are the brackets cut for, and can they be changed?
5. Are ventilation grilles included, and where do you expect the openings?
6. What does the kit assume about the floor?
7. What is not in this box that I will need?

Question seven is the only one that matters. A vendor who calls the package complete and then names electrical, floor, and vents in the next breath is being honest about a term of art. One who does neither has told you something too.

Everything a kit leaves out is a decision, and decisions are cheapest while the walls are still open. Settle the circuit, the floor, and the vent placement first. If that arithmetic changes your mind about the approach entirely, the kit, DIY, and prefab comparison is where to look next. Order the crate second.