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Apartment sauna construction | Vannitoaremont 24
Vannitoaremont 24 builds apartment saunas in Tallinn and Harju County as part of our sauna construction service. A 3 m² electric-heater sauna beside a bathroom must meet tighter ventilation, electrical and neighbour-related constraints than a sauna in a detached home. By the end of 2025, we had built 74 apartment saunas, including 31 in Lasnamäe and Mustamäe panel buildings.
An apartment sauna has no chimney or external wall of its own. Its vapour barrier contains moisture, while the existing ventilation duct carries it away. We inspect the duct with a camera during the site visit.
- Licensed and insured
- 100% satisfaction guarantee
- 74 apartment saunas by the end of 2025
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When to plan the construction of an apartment sauna
Full renovation of the bathroom is already planned
During the complete renovation of the bathroom, the walls are open, and the supply line and ventilation connection of the sauna are laid at the same time, because the later opening of the wall with the finished tile will take 2 working days to restore the tile and membrane alone. The existing bathroom renovation quote and the empty adjacent room are a sign that the sauna belongs to the same quote.
Old apartment sauna heats up slowly
A 3-kilowatt heater for an apartment sauna built in the 1990s heats the sauna to 80 degrees in 70 minutes, and a 4.5-kilowatt heater suitable for a 3-square-meter room does the same in 40 minutes. Darkened siding and moldy corners also indicate that the vapour barrier is worn or missing.
There is unused storage space next to the bathroom
A storage space with a floor area of 3 square metres, where the bathroom ventilation duct extends and whose ceiling is 2.5 metres high, is suitable for the sauna. We build the ceiling of the sauna ceiling at a height of 2.2 metres, and the space above it accommodates the insulation and the extract ventilation pipe.
Why an apartment sauna needs a vapour barrier and an air gap
Sauna room air at 80 degrees holds 290 grams of water vapour per cubic meter and room air at 20 degrees only 17 grams, and when steam is thrown, the steam pressure pushes the moisture through the wood insulation. On the 20-degree panel wall behind the insulation, the steam cools to the dew point and turns into water, which remains between the wall and the insulation without drying.
Therefore, there is a continuous vapour barrier between the insulation and the lining board, a paper with aluminum foil, each joint of which is covered with foil tape, and a 20 mm air gap behind the lining board, which dries the back of the board after each sauna session. The vapour barrier stops moisture, the air gap dries the wood, and the fresh air coming in from behind the heater, together with the high extract ventilation, changes the air in the sauna, so that the panel wall remains dry even after years of use.
How the Construction of Apartment Sauna Works
Check the electrical supply and ventilation
The 4.5-kilowatt heater gets a separate line from the apartment's electrical panel with a residual current device, because the heater takes 19.6 amps from the single-phase supply. In the ventilation duct, we measure the amount of air extracted with an anemometer and require 40 cubic metres per hour, because this is how the air in a 3-square-meter sauna with a 2.2-meter ceiling changes 6 times an hour.
Frame, insulation, waterproofing and vapour barrier
On the first business day, we build the wooden frame of the walls and ceiling and install 50 mm stone wool insulation. On the second day, waterproofing is applied to the floor and the lower 30 centimetres of the walls, and a vapour barrier with foil is fixed on top of the insulation, and before the sauna panelling, a photo of each wall is left from the membrane, which is handed over with a warranty document.
Panelling, heater, benches and first heating
On the third day, the sauna panelling are nailed to the rafters so that there is a 20-millimeter air gap behind the board, and on the fourth day, we install the heater, the benches at a height of 45 and 90 centimetres, and a glass door. Before handing over, we heat the sauna to 80 degrees for the first time, check the closing of the extract ventilation check valve and show the customer the control panel setting.
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- Licensed and insured
- 100% satisfaction guarantee
Ventilation and apartment association approval
In the panel houses of Lasnamäe and Mustamäe, the bathroom ventilation is a common channel with natural draft that passes through all the apartments of the same riser, and the extract ventilation of the sauna is connected to it through a non-return valve, so that warm moist air does not move to the bathroom of the upper neighbour. Before starting the work, Vannitoaremont 24 asks the apartment association for written approval to connect to the duct and for a separate supply line for the heater, and sends the board a connection diagram with the power of the heater.
Apartment sauna cost and timescale
The construction of an apartment sauna costs from 4,470 euros, when ordered separately, the installation of an electric heater costs from 480 euros and the construction of a sauna bench from 640 euros, and the construction of a humid, 45-degree steam sauna costs from 5,200 euros. The construction of a 3 square meter apartment sauna takes 4 working days: the first day is spent on the framework and insulation, the second on waterproofing and vapour barrier, the third on the installation of sauna panelling and the fourth on the installation of the heater and stage. By the end of 2025, a separate line will be connected from the apartment shield to 97 apartment and steam sauna heaters.
Renovating a 1990s apartment sauna near Pirita Harbour
Owner: Elmar T., old apartment sauna in Pirita apartment building. Location: Near Pirita Harbour, Pirita. Job number: 1836.
Electrical and ventilation checks during the site visit. The old 3 kilowatt heater heated the sauna to 80 degrees in 70 minutes, and the darkened panelling in the corners showed that the vapour barrier had failed. Our surveyor checked over the ventilation channel with a camera and measured the extraction with an anemometer at 40 cubic metres per hour.
Apartment Association approval. Before the work began, the apartment apartment association gave written consent, to which the duct connection diagram and the 4.5 kilowatt capacity of the heater were attached to the application.
Demolition, frame, insulation, waterproofing and vapour barrier. On the first day, the old lining board, wet insulation and the heater left in a construction-waste bag. In the next two days, the framework, 50 mm stone wool, membrane for the floor and the lower 30 cm of the walls, and a foil vapour barrier with taped grout joints came.
Panelling, heater, benches and first heating. The panelboard went on the wall with an air gap of 20 millimetres, the 4.5-kilowatt heater got its own line from the flat’s electrical panel with a residual current device, the heights of the benches are 45 and 90 centimetres, and the sauna was heated to 80 degrees for the first time upon delivery.
Repair price: €5,120 including VAT: construction of the apartment sauna 1 × €4,470 = €4,470 and a separate line of the heater from the apartment shield with a residual current device for the price of electrical work in the bathroom 1 × €650 = €650. There is no travel cost at the Pirita facility.
Duration of repair: 5 working days in 2025, of which demolition of the old sauna 1 day, frame and insulation 1 day, waterproofing and vapour barrier 1 day, sauna panelling 1 day and heater, benches and first heating 1 day.
Finished room: The new 4.5-kilowatt heater heats the sauna to 80 degrees in 40 minutes, the old 3-kilowatt heater took 70 minutes.
Frequently Asked Questions
Does the apartment sauna need the consent of the apartment association?
Yes: the connection of the extract ventilation of the sauna to the common ventilation duct of the house and the new line of the heater from the electrical panel require the consent of the apartment association. We ask the apartment association in writing for approval before the work begins and add the duct connection diagram and heater capacity to your enquiry.
How much electricity does an apartment sauna use?
The 4.5-kilowatt heater runs at full power during heating and consumes 3 kilowatt-hours in 40 minutes, and an hour-long sauna visit adds 2 kilowatt-hours to it as thermostat switches. Three sauna evenings a week makes 60 kilowatt-hours a month.
Can a panel building floor support the heater and sauna stones?
Yes. A 4.5-kilowatt heater weighs 40 kilograms with stones, which is distributed on the floor through four legs, and a panel building made of reinforced concrete can sometimes carry such a load without additional reinforcement. We install a fire-resistant base tile under the heater, which protects the floor tile from the heat.
How high is the ceiling of an apartment sauna built?
We build the ceiling of the sauna ceiling at a height of 2.2 metres under the 2.5-meter ceiling of the panel building apartment, because the lower ceiling reduces the heated air volume and keeps the heat above the bench. At the 90-centimeter height of the upper bench, there is 1.3 metres of space above the head of the sitter and the required 110 centimetres between the stones of the heater and the ceiling.