Aufguss: What the Sauna Room Needs for the Ritual

Sauna Dekor Spa Solutions engineering team, Istanbul · project and press enquiries: Alican Aykaç, Managing Partner

Updated: 12 November 2026

A guide from Sauna Dekor Spa Solutions, an Istanbul manufacturer of saunas, hammams and steam rooms since 1987 — 40 years — with projects in 41+ countries.

Those numbers belong to the operator, but most of them land on the architect first. A sauna that will host an aufguss needs a heater with enough stone mass to turn litres of water into steam, a clear floor between the heater and the benches, benches at least 0.80 m deep, an anteroom where guests can wait, ventilation that clears the room between sessions, and a cool place for the sauna master afterwards. This guide takes each requirement in the order a drawing answers it, with the arithmetic shown and the sources listed at the end.

Table of contents

• What is an aufguss?
• How hot is the sauna during an aufguss?
• How much water goes on the stones in one aufguss?
• How long does an aufguss last?
• What does the heater’s stone mass have to deliver?
• Where should the heater stand in an aufguss sauna?
• How deep should the benches be?
• What does ventilation have to do before and after?
• What water and fragrance can go on the stones?
• How many aufguss sessions can one sauna master run?
• How does an aufguss fit into a thermal suite schedule?
• What changes for an aufguss in a Gulf hotel or club?
• Can a private villa sauna host an aufguss?
• What should the specifier put on the drawing?
• Frequently asked questions

An aufguss is the production of steam by pouring water, ice or both onto the hot stones of a sauna heater, according to the definition in section 4.1 of DGfdB R 26.30.04. The guideline covers every sauna that is not used exclusively in private, and only sessions run manually by trained staff, not by guests with a ladle.

The word is German for “infusion” or “pouring on”, and the session is led by a sauna master (Saunameister), who pours, announces the fragrance and moves the hot air with a towel, a fan or birch branches. Wikipedia’s sauna article describes the same practice: the person in charge uses a large towel to circulate the hot air through the room, and a session can take up to 10 minutes.

The guideline names five types of aufguss: the classic aufguss with water, the classic aufguss with ice balls, a combination of the two, the show aufguss with light, music and themed towel work, and the Wenik aufguss with leafy birch branches in the Baltic and Russian tradition. Each type puts the same demand on the room: stones hot enough to flash water into steam, and space for a person to work between the heater and the guests.

An aufguss is therefore not a feature of the heater. It is a way of running a sauna, and the room either allows it or does not. A standard Finnish sauna cabin built for self-service bathing can be too small, too shallow or too cluttered around the heater for a sauna master to work safely.

DGfdB R 26.30.04 assumes a commercial sauna room held at 90 to 100 °C, measured about 1.00 m above the uppermost bench, with low humidity that an aufguss raises only briefly. All of its water quantities and session times refer to 90 °C at that measuring point; an operator who runs the room cooler takes responsibility for adjusting both.

The measuring point matters for the drawing. A sensor on the wall near the ceiling reads hotter than the air at head height on the top bench, and a sensor next to the heater reads hotter still. If the control sensor is placed where the heater manufacturer specifies it, the operator needs a second, visible thermometer at the guideline’s reference height so that the sauna master can see what the guests are sitting in.

For comparison, the Harvia Forte manual gives a pleasant bathing temperature of 50 to 60 °C for a home sauna heated with that model, and says that the humidity a low-temperature sauna allows cannot be reached at higher temperatures. The aufguss sauna runs 30 to 40 °C hotter than that, and dry, because the steam is added in doses during the session rather than being present all the time.

Up to 30 g of water per cubic metre of room volume, the value for which DGfdB R 26.30.04 says long experience exists. The 2025 draft allows up to 60 g per cubic metre where tests in the specific sauna room have shown it to be tolerable, and the operator writes the tested figure into a staff instruction. Ice counts too: its weight is multiplied by 0.92.

The quantity depends on the room volume and temperature, the size and output of the heater, the amount and type of stones, the type of aufguss and the height and shape of the ceiling, according to section 7.5.2 of the guideline. It also sets one hard limit: the water must never be so much that it reaches the hot parts of the heater beyond the stones, and it should not land on the heating elements.

The table below turns the per-cubic-metre values into litres for four room sizes, and into pours with a 0.2 litre ladle, the maximum ladle volume the Harvia Forte manual specifies. One litre of water weighs 1 kg, so 30 g per m³ is 0.03 litres per m³.

Those litres are split over the session. A sauna master typically pours in several rounds and waves the steam down between them, so a 40 m³ room at 30 g/m³ does not receive 1.2 litres at once but 6 ladles over several minutes. The heater has to recover between rounds, which is why stone mass matters more than the kW figure on the nameplate.

The guideline also says how to count ice. One kilogram of ice is one litre of water, but a formed ice ball contains trapped air, so its weight is multiplied by 0.92 to find the water it contains. An operator who adds a 1 kg ice ball to a 40 m³ room at 30 g/m³ has used 0.92 of the 1.2 litres available for that aufguss.

Between 6 and 10 minutes, counted from the moment the sauna master enters the room until they leave it, with an absolute maximum of 12 minutes, according to section 7.6.1 of DGfdB R 26.30.04. The guideline also asks operators to keep each guest’s stay in the sauna room to no more than 15 minutes, and warns against airing the room briefly to stretch that limit.

Competition rules are different and are explicitly outside the guideline’s scope. The Modern Classic Cup run by Aufguss WM sets a total length of 12 to 15 minutes, with 14 minutes described as ideal, and limits the welcome and introduction to 90 seconds. Those are show performances before a jury of 3 to 5 people, not the hourly sessions of a hotel spa.

For the building, duration translates into two things. First, the heater must hold the room at around 90 °C across 10 minutes of repeated pours with the door opened at least twice. Second, the waiting guests need somewhere to wait, because the recommended access rule, described below, clears the room 15 minutes before each aufguss.

It has to hold the energy that turns the aufguss water into steam. Heating 0.75 litres from 20 °C to 100 °C takes about 251 kJ, and evaporating it takes about 1,693 kJ more, roughly 1.94 MJ in total. If the stones alone supplied that, 45 kg of stone would cool by about 54 K on average; a 15 kW heater needs about 129 seconds to put the energy back.

The arithmetic behind those figures is short. Water needs 4.186 kJ per kilogram per kelvin to warm up and about 2,257 kJ per kilogram to evaporate. Dense rock such as granite stores roughly 0.79 kJ per kilogram per kelvin. At 30 g/m³ in a 25 m³ room, the water is 0.75 kg: 0.75 × 4.186 × 80 = 251 kJ, plus 0.75 × 2,257 = 1,693 kJ.

The two heaters in this guide show why the stone quantity is the number to read first. The EOS Mythos S45, a floor-standing heater in 12 kW and 15 kW versions for rooms up to about 25 m³, holds 45 kg of stones, according to EOS. The Harvia Forte holds approximately 100 kg of stones kept at 220 to 260 °C in its insulated stone space, according to Harvia’s manual. Twice the stone mass halves the temperature drop for the same pour.

At the tested maximum of 60 g/m³, the same 25 m³ room receives 1.5 litres and the energy doubles to about 3.9 MJ. 45 kg of stone would then drop by more than 100 K on average, and the 15 kW heater would need about 4.3 minutes to recover. That is the practical reason large aufguss rooms use large heaters or several heaters, and why the operator’s tested water quantity has to be agreed with the heater choice, not after it. Our guide to types of sauna heaters compares stone capacity across heater families.

We do not manufacture heaters. EOS and Harvia make them, and any CE marking or EN 60335 conformity on a heater belongs to its manufacturer, not to us. What we decide is the room around the heater: its volume, the insulation that keeps heat in the cabin rather than in the wall, and the space the sauna master needs to use the stones.

In the middle of the room, if the plan allows it. Section 5.2.1 of DGfdB R 26.30.04 lists three spatial conditions: a sufficient free floor area between the heater and the benches for the ceremony, a central heater position as an advantage, and no fixtures around the heater or the free area that would get in the way of the towel.

A heater on the end wall is the common layout in hotel and club saunas, because it keeps the benches on one or two sides and the door short. It works for an aufguss when the free area in front of the heater is wide enough for a person to turn with an outstretched towel without touching the heater guard, the benches or the guests’ feet on the lowest tier. It does not work when the heater sits in a corner behind a bench return.

The “no fixtures” condition catches details that are easy to draw without thinking about a towel: wall lamps at shoulder height next to the heater, a thermometer on the heater wall, a bench backrest that overhangs the free area, or a ceiling light hanging into the space above it. All of them belong on the walls away from the heater, or recessed into the ceiling.

The photograph above is from the sauna we designed, manufactured and installed for the Diplomatic Club spa in Doha, delivered in 2022 together with its steam rooms, spa hot tub and pool areas. The heater stands on the end wall against a grey stone-clad panel, with two bench tiers running along one side and a clear timber floor in front of the heater. It is a self-service club sauna, not a room we delivered for aufguss, and it shows the end-wall layout this section describes.

At least 0.80 m for each tier that serves as both a seat and a foot rest, and 0.60 m for the highest tier, according to section 5.2.1 of DGfdB R 26.30.04. The guideline defines an aufguss room’s benches as three or four ascending tiers, because a full room of guests seated at different heights is what the ceremony plays to.

The depth rule exists because in an aufguss room the guest on the tier above rests their feet on the tier below. A 0.60 m lower tier leaves no space for a seated guest’s hips and the feet of the guest behind, and people end up sitting sideways or standing. The highest tier carries no feet, so 0.60 m is enough there.

Three or four tiers also set the ceiling height. The Harvia Forte manual recommends no more than 1,200 mm between the top bench and the ceiling, because heat collects at the top. A room with three tiers, the top one at around 1,100 mm above the floor, therefore needs a ceiling around 2,300 mm high. Every added tier raises the room, and every metre of extra height adds volume that the aufguss water has to serve.

Bench timber is part of the same decision. At 90 °C and repeated steam pulses, the seat has to stay touchable and dimensionally stable; the species, board section and fixings are the same questions as in any commercial cabin, and and they are settled with the rest of the cabin rather than repeated here.

It has to clear the steam and the fragrance between sessions and keep the air breathable during them. The Harvia Forte manual asks for the air in a sauna room to be changed 6 times an hour, with the supply opening low on the wall and the exhaust high, near the ceiling. For a 40 m³ aufguss room, 6 air changes an hour is 240 m³ of air an hour.

The guideline’s access rule gives ventilation a fixed window. Guests are asked to leave 15 minutes before the aufguss and are let back in 5 minutes before it, so the room stands empty for 10 minutes. At 6 air changes an hour, 10 minutes is exactly 1 full air change, enough to replace the previous session’s scented, humid air before the next group sits down.

Heater manufacturers also give minimum openings. EOS specifies a minimum air inlet and outlet of about 1.2 × 0.3 ft for the 12 kW Mythos S45 and 1.2 × 0.4 ft for the 15 kW version, roughly 35 × 9 cm at the larger size. Those are minimums for heat, not for aufguss; in a large room the mechanical engineer sizes the flow, and the drawing shows where the openings sit relative to the heater and the free area. Our sauna ventilation guide covers the openings, the fan and the drying cycle.

One detail matters for an aufguss in particular. The exhaust must not pull the steam straight out before it reaches the guests, so it is placed away from the heater, usually on the opposite wall and high. A drying valve that stays closed during heating and bathing and opens afterwards, as the Harvia manual shows, lets the room dry overnight without losing heat during the day.

Clean household water only. The Harvia Forte manual sets recommended limits of less than 12 mg per litre of humus, less than 0.2 mg per litre of iron, 0.05 mg per litre of manganese and less than 100 mg per litre of calcium, and forbids humous, chlorinated and sea water. It also warns against pool or spa water, because chlorine gas can form on the stones.

In a hotel spa the tempting shortcut is the nearest tap, and in a wet area that tap may be on the pool or hot-tub circuit. The aufguss bucket needs its own supply point of drinking-quality water, outside the sauna room, where the sauna master prepares the infusion. The calcium limit is not cosmetic either: the Harvia manual notes that hard water leaves a white layer on stones and heater surfaces that reduces their heating performance.

Fragrance has its own rules. Harvia allows only perfumes designed for sauna water, used as the package instructs. DGfdB R 26.30.04 adds that the aufguss water is mixed outside the sauna room, in a place unauthorised people cannot reach, following the fragrance’s safety data sheet and dosing instructions, and that fragrances, often flammable liquids, are stored sealed in a hazardous-substance cabinet. That cabinet and the preparation counter are rooms or furniture on the plan, not afterthoughts.

One per working hour, according to section 6.4.2 of DGfdB R 26.30.04, with shorter sessions under 6 minutes regulated separately through a risk assessment. Between sessions the sauna master cools down in an area that is not heat-loaded, drinks, changes and can do light work such as supervision or cleaning.

The guideline also sets a training floor. The staff member professionally responsible for aufguss must be a certified sauna master of the German Sauna Association or have completed comparable training with at least 50 hours of theory, an exam and a certificate. Pool attendants, physiotherapists and sports scientists qualify after a basic course of at least 12 hours, and all staff renew first-aid training every 2 years.

For the building, the staffing rule turns into a room list. The sauna master needs a staff changing space, a cool place to recover and a shower that is not in the guests’ circuit. A spa that plans an hourly aufguss across a 12-hour day, for example from 10:00 to 22:00, needs 12 sessions and, at one per hour per person, at least 1 sauna master on duty for every hour of it, plus cover for breaks. Our hotel spa design guide lists the back-of-house rooms a thermal area needs.

Through the access rule and the rooms next to the sauna. DGfdB R 26.30.04 recommends asking guests to leave the sauna 15 minutes before each aufguss, releasing the room 5 minutes before it starts and starting on time, so that nobody sits in the heat for more than 15 minutes. It adds that a large anteroom in front of the sauna helps.

That anteroom is where the queue forms, and in a hotel it has to be pleasant enough to wait in: seats, a water point, a clock and the posted aufguss plan. The guideline requires the plan to state the time, place, fragrance and intensity of each session, and recommends a three-level intensity scale, with any session beyond it, such as a Wenik aufguss, flagged separately.

After the session, guests look for cold. The guideline names fresh air and cold water as suitable ways to bring body temperature back to normal. A shock bucket or a cold shower within a few steps of the sauna door does that for a full room of guests at once, and it sits in the same wet zone as the rest of the thermal suite: heat, cold, rest, in that order.

Three things: where people cool down, what water reaches the bucket, and how the plant serves a room that runs hotter than the outdoor air only by degrees in summer. None of them changes the guideline’s numbers; 90 °C, 30 g/m³ and 10 minutes are the same in Dubai as in Düsseldorf.

The cooling point comes first. The German guideline assumes that a short walk in fresh air helps guests and staff cool down. On a Gulf terrace in July that air can be above 40 °C, which is a warm room, not a cooling area. The cool-down space in a Dubai, Doha or Riyadh spa is indoors and air-conditioned, and it is drawn next to the sauna and the cold showers rather than outside.

The second is water. The aufguss bucket should be filled from a dedicated drinking-water point, checked against the heater manufacturer’s limits, and kept away from the pool, hot-tub and irrigation circuits that share a hotel’s plant room. The third is air: a mechanical ventilation system that takes outdoor air at 40 °C and above still dilutes the steam, but the supply has to be conditioned so that the anteroom and relaxation area stay cool.

Our Dubai office coordinates sauna projects for hotels and clubs across the Gulf, and the conditions above are the ones we check first when an operator mentions aufguss in a brief.

Rarely in the full sense. DGfdB R 26.30.04 applies only to saunas not used exclusively in private, and in an interview published by Kemitron the aufguss trainer Udo Mohr says private saunas are usually far too small, often only 2 to 3 m². At 8 m³ and 30 g/m³, the whole aufguss is 0.24 litres, a little more than 1 ladle.

A villa sauna can still be built with the same logic in miniature: a heater with a generous stone quantity, a small free area in front of it, a top bench no more than 1,200 mm below the ceiling and a supply of clean water for the bucket. What it cannot offer is the audience and the rhythm of a timetabled session, which is what most people mean by aufguss.

10 items make an aufguss sauna buildable and give the operator what the guideline expects. Each one below is a line on a plan, a section or a schedule, and each has a number or a source behind it in the sections above.

1. Room volume in m³, with the tested or assumed water quantity per m³ and the resulting litres per aufguss.
2. Design temperature of 90 to 100 °C at 1.00 m above the top bench, with a visible thermometer at that height.
3. Heater model, output and stone quantity in kg from the manufacturer’s data, and the recovery time for one aufguss.
4. Heater position, central if possible, and the dimensioned free floor area between heater and benches.
5. No lamps, backrests or fittings in the free area or around the heater.
6. Three or four bench tiers, 0.80 m deep where feet rest, 0.60 m at the top, and no more than 1,200 mm from top bench to ceiling.
7. Supply low, exhaust high and away from the heater, with the air flow stated per hour.
8. A drinking-water point and preparation counter outside the room, and a hazardous-substance cabinet for fragrances.
9. An anteroom sized for the waiting queue, with the aufguss plan posted.
10. A cold step within a few metres of the door and an indoor cool-down space for guests and staff.

Sauna Dekor has designed and built saunas, steam rooms, hammams and pools since 1987, 40 years of manufacturing in Istanbul in our own facility in İkitelli OSB, with a team of 19 employees, working under TS EN ISO 9001:2015, and with projects delivered in 41+ countries. We design the sauna room, manufacture the cabin, benches and cladding, and install it with our own teams travelling from Istanbul.

What we do not make is equally clear. Heaters, control panels, fans and steam generators are not our products; EOS, Harvia and Condair make them, and any CE marking or EN 60335 conformity on that equipment belongs to its manufacturer. The TS EN ISO 9001:2015 certificate is ours. We have no aufguss room on our own delivery record to cite, so this guide relies on the German guideline, the heater manufacturers’ documents and the club sauna we delivered in Doha.

For hotels and spas that run aufguss sessions, the sauna is planned as part of commercial thermal suites.