Caring for your sauna (and steam room)

The short answer

Most sauna care comes down to a few habits and two yearly jobs.

• Before each session, check the heater is clear and the vents are open.
• During it, sit on towels and use small ladles of clean household water on the stones only.
• After it, switch off, check the heater has stopped, take everything out and dry the room.
• Clean with mild products only. No bleach, chlorine, harsh cleaners, pressure washers or abrasive pads, and no ordinary stain or varnish inside the hot room.
• Re-stack and check the stones at least once a year, more often with frequent use.
• Give the room a thorough clean and inspect the benches, hardware and heater, at least yearly.
• Leave electrical work to professionals, and call for help when something changes.

Everything else (the exact drying time, the cleaning interval, whether to oil the benches) depends on your heater and timber manufacturers, and they don’t all say the same thing. Where they differ, this guide says so. Your own product manuals take precedence.

If your sauna is brand new, start with our first-use guide, which covers the first heats, the new-heater smell and your first session. If your room has infrared emitters, see also infrared and hybrid sauna care.

Before each session

A minute of checks prevents most problems:

• Nothing on or near the heater. No towels, clothing, buckets or other objects on it, against it or over its guard.
• Vents open as the room’s ventilation design intends. The supply and exhaust stay open while the heater runs; only a closable drying vent, if fitted, is kept closed while heating and bathing (Harvia).
• Stones in order. No element showing between the stones, and no fragments on the floor beneath the heater.
• Check the room before switching on, and before any timed or remote start. Harvia’s control manuals ask for this every time, because a heater started remotely has nobody standing beside it.

During the session: ladle and water use

How you use water affects both the löyly and the heater.

• Small ladles. Harvia’s manuals set a maximum ladle volume of 0.2 litres. More than that doesn’t all evaporate, and water can splash boiling off the stones.
• Onto the stones only. Not onto the heater casing, guard or walls, and never when someone is near the heater.
• Let the stones recover between ladles. Water that runs through rather than flashing to steam means the stones need time to reheat.
• Clean household water only. Harvia publishes limits for minerals such as iron, manganese and hardness, and prohibits chlorinated water and seawater. Never use pool or spa water, a real risk in Queensland homes with pools. If you are on tank or bore water, check it against the limits in your heater’s manual. One maker notes that hard water leaves white deposits that reduce the stones’ ability to store heat.
• Fragrances as directed. Use only scents made for sauna water, diluted as their maker directs. Neat essences, alcohol and herbs on the stones can catch fire, and one maker says strong essences speed up stone breakdown.
• Use bench towels. Heater manuals ask for them to keep perspiration off the benches, and Harvia also warns against smearing sauna scents, honey or other body-care products on the timber.

Why it matters: the wrong water leaves deposits on the stones and corrodes heater parts, and heavy throws of water cool the stones faster than they can recover, which hastens cracking.

After every session

The aim is simple: don’t let moisture sit in the timber.

1. Switch the heater off, unless you are running a short drying heat. Harvia says to switch off after bathing, and notes that leaving the heater on briefly can help dry the timber.
2. Check the heater has actually stopped heating when you switch off or the timer ends. Harvia asks for this every time.
3. Take everything out: towels, clothing, the bucket. Leave no standing water.
4. Wipe the benches and backrests with a clean towel or a damp cloth.
5. Dry and ventilate the room. Manufacturers agree on the principle but not the method. Harvia’s care instructions suggest leaving the heater on for about 10 minutes, opening the vent and leaving the door ajar. Another heater maker suggests 30 minutes with the heater on, then opening the vents and door. LeisureCraft asks owners to open the door so moisture can escape. Use the method in your heater’s manual.
6. Let any automatic drying cycle finish. Some controls dry the room for you; Harvia’s Xenio control, for example, can hold the room at about 40 °C for 45 minutes after switch-off, with the fan running if one is connected.

Regular cleaning

How often depends on use. For a family sauna, Harvia’s care instructions call for a thorough clean one to three times a year, and its heater manual says to wash benches, walls and floor at least every six months. Another heater maker says one to four times a year, and a third says a sauna in daily use should be washed down at least once a week.

What to use

• Warm water and a mild detergent suited to saunas. Harvia specifies slightly alkaline products (pH 8–10).
• A soft cloth, sponge or soft brush, working along the grain.
• A rinse with clean water, then a thorough dry: run the heater briefly and ventilate.

What never to use

• Bleach, chlorine or harsh household cleaners. LeisureCraft rules them out on cedar, and other makers say no detergents containing ammonia or chlorine.
• Pressure washers inside the room.
• Abrasive pads or scourers on timber.
• Paint, varnish, lacquer or ordinary exterior stain on any interior surface.

Sweep or vacuum under the benches as part of each clean, including any stone grit under the heater. If a removable floor grate or duckboard is fitted, take it out, clean and dry the floor, and scrub and dry the grate before putting it back. Wipe dust off the heater casing with a damp cloth; Harvia suggests removing lime marks with a 10% citric acid solution, then rinsing.

Door, glass, hardware, floor and lighting

• Glass. Clean it like other glass, when the room is cool, without abrasive pads, and keep the cleaner off the timber frame. Harvia’s care sheet says glass elements must be checked after installation, including that the fittings are tight enough, and treats this as the owner’s responsibility. Our glass and doors guide has more.
• Door, hinges and handle. Check that the door still opens easily outwards and closes fully, and that hinges, handle and glass fittings are tight. LeisureCraft asks for doors, hinges and handles to be inspected in spring and autumn and screws and bolts tightened yearly. Harvia says a timber door frame and handle can be treated with a heat- and moisture-tolerant sauna protection product.
• Floor. Keep it clean and dry, with grit and stone fragments swept from under the heater. Harvia notes that stone particles and impurities in the water can stain or damage sensitive floor coverings, and that water on a sauna floor must drain to a floor waste where one is fitted.
• Lighting. Clean light covers only with the power off and the fitting cool, using a damp cloth. Never remove a cover or open a fitting yourself; if a light fails, flickers or its cover is cracked or scorched, have a licensed electrician check it. Our lighting guide explains sauna-rated fittings.
• Controls. Wipe the control panel with a soft, barely damp cloth, never spray it, and keep the temperature sensor and its cover undisturbed (see controls, sensors and timers below).

Marks, sanding and bench oil

Benches darken with use, and pale timbers show marks most. A clean along the grain removes most of them. For stubborn marks, manufacturers suggest a light sanding with fine sandpaper, always with the grain, followed by a wash and a full dry.

Oiling the benches is optional, and the manufacturers’ positions differ:

• Harvia recommends paraffin oil on benches one to three times a year, depending on use. It says to apply it to completely dry timber, treat the bench ends especially well, and test it on the underside first because it deepens the colour.
• Another heater maker suggests a wood oil suitable for saunas, such as paraffin oil, if needed after washing or sanding.
• LeisureCraft says the interior cedar of its saunas is normally left natural, and that anything applied must be a product designed specifically for sauna interiors.

Walls generally need nothing. Harvia says wall protection is unnecessary in a family sauna.

Drying and readiness times come from the product, not a rule of thumb. For example:

• Harvia’s care instructions say to let its paraffin oil stand for 30 minutes to an hour, then wipe the surface dry if needed; heating the sauna speeds drying.
• Tikkurila says its Supi Laudesuoja bench paraffin oil is ready once it has absorbed into the wood, which depends on the timber’s porosity.
• Wall and ceiling protectants are a different category. Tikkurila’s Supi Saunasuoja, for instance, is not for benches and is ready for use after about 48 hours.

Whatever you use, choose a sauna-specific product, follow the manufacturer’s product data sheet and let it dry fully before the next session. Our timber guide explains how different species age and mark.

Heater stones

Stones break down with repeated heating and cooling, and they matter more than they appear to. They store the heat that makes löyly, and air has to rise freely through them for the heater to work. Crumbled or tightly packed stones choke that airflow, which slows heating, makes the elements run hotter and shortens their life, and can trip the heater’s overheat protector. Harvia’s guarantees exclude damage caused by non-recommended stones, and several of its manuals exclude faults from disintegrated stones.

The routine Harvia asks for:

• Rearrange the stones at least once a year, more often if the sauna is used frequently. Harvia’s newest Spirit manual and its help centre go further and suggest replacing them about yearly in a family sauna used around twice a week.
• Remove the fragments from the bottom of the heater and the floor beneath it, and replace any stones that have cracked or crumbled.
• Reload loosely, with the elements fully covered. Never wedge stones between or against the elements; stones should support each other.
• Watch the first two months after new stones go in. Harvia notes that they settle fastest in that period, so check that no element has become exposed.
• Use only stones the heater manufacturer approves, in the size its manual specifies.

Other manufacturers set their own intervals for their own heaters, such as yearly or every 500 operating hours, whichever comes first, and as often as every two or three months in commercial use. These are examples of how intervals tighten with use, not Harvia’s guidance; the manual for your heater governs.

Our sauna stones guide covers rock types, rounded versus angular, loading step by step, the signs that stones are breaking down and how to re-stack them. If you would rather not do it yourself, our service team inspects, restacks and replaces stones.

The heater and its elements

Owner care of the heater itself is limited to keeping it clean and clear: with the heater switched off and cold, Harvia asks for dust and dirt to be wiped from it with a damp cloth. Beyond that, leave it to qualified people. Harvia states that all service operations must be done by professional maintenance personnel, and any work on the electrical supply is for a licensed electrician.

Harvia’s troubleshooting links common symptoms to likely causes:

The overheat protector cuts the heater’s supply when the area around it gets dangerously hot. On some Harvia models its reset button is inside the heater’s connection box, and only a person authorised to carry out electrical installations may reset it, after the cause has been found. Why it matters: resetting without fixing the cause just lets the same fault happen again.

Element and inspection intervals are not the same across brands. Have the heater and its connections inspected as recommended by your heater manufacturer.

Controls, sensors and timers

• Don’t move, cover or knock the temperature sensor. It controls the heater and protects against overheating. If a sensor or its cover has been dislodged, have it refitted to the manual’s position.
• Switch off at the end of each session, and check the control and heater are off at the end of the day.
• Don’t rely on the timer as your only off switch. Heaters have built-in on-time limits, but the habit of switching off is still worth keeping.
• Remote and timed starts are only safe with the safety devices the manufacturer requires, such as a door switch or a heater cover sensor over the heater (or a heater certified to the covering test the control’s manual names), and with the room checked first.
• Error codes on a digital control: look the code up in the control unit’s manual, then call a technician rather than repeatedly resetting.

Our controls guide explains sensors, safety devices and remote start.

Combi heaters (steam from the heater)

Some heaters, such as Harvia’s Virta Combi, have a built-in water reservoir that adds humidity. Harvia’s instructions for them add a few owner tasks:

• Fill the reservoir before use, while the heater is cold.
• Drain it after every use, once it has cooled, so impurities don’t concentrate.
• Dry the room thoroughly after steaming: heater on and ventilation at maximum for a while, then switch off.
• Descale the evaporator with a household descaler of the kettle or coffee-maker type, as the manual directs.

Water-connected heaters also need somewhere for a leak to go; Harvia calls for a floor drain in the sauna or washroom.

Outdoor saunas

An outdoor sauna has a second set of care tasks: its exterior, roof and base. LeisureCraft, whose outdoor kits are made from cedar, sets out the following.

• Exterior finish. Untreated cedar weathers to silver-grey, which LeisureCraft says is normal and does not reduce its durability. To hold the original colour, apply a penetrating exterior finish suited to cedar to clean, dry timber, and reapply when the colour fades. Never use exterior stain inside.
• Roof and hardware. In spring and autumn, inspect the roofing, doors, hinges, handles and vents. Keep leaves and debris off the roof and away from the walls.
• Base and drainage. Check that the base still drains water away from the sauna.
• Barrel bands. Cedar staves swell and shrink with the weather. Check the stainless steel bands within the first month, then periodically; LeisureCraft’s manuals give about every six months. Tighten them so they are secure, but not excessively.
• Wood-fired heaters. Remove ash only when it is completely cool, and have the chimney and flue inspected and cleaned as required.

LeisureCraft’s warranty excludes insufficient or improper maintenance, and its manuals list band tightening, cleaning and staining as the owner’s responsibility. Our outdoor kit guide explains how Queensland’s sun and humidity affect cedar.

Steam rooms

A steam room has no timber or stones, but it has a generator, water and a lot of condensation. The essentials:

• Let the automatic drain run. Many generators drain and flush themselves after use. Switching off at the isolator can stop this, so use the control as the manual describes.
• Descale on schedule. Scale from hard water is the main cause of generator faults. Manufacturers set descaling by operating hours and water hardness; one maker’s intervals range from 30 to 500 hours depending on hardness. Follow your generator’s manual and its service indicator.
• Keep the floor waste clear of hair and debris, and check that water drains away freely.
• Clean tiles and grout with non-abrasive products suited to the tile and grout system, and rinse.
• Check the silicone and grout at the steam outlet, sensor, lights, door frame and changes of plane. Cracked or missing sealant lets steam into the wall, where damage is hidden. Have failed joints repaired promptly.
• Keep the steam outlet clear, and remember the generator’s discharge water is hot. Harvia advises allowing about 24 hours of cooling before opening its sediment cup.
• Have the generator serviced as its manufacturer specifies. For community and institutional use, Harvia requires a thorough service at least twice a year.

Our steam guide explains how a steam room is built to cope with constant vapour.

Maintenance schedule at a glance

This table collects the intervals that manufacturers publish. Where your manuals give a different interval, follow them.

Commercial rooms

Hotels, gyms, spas and body corporates need far more than a home routine: daily cleaning, a written plan, approved products and records. The manufacturers’ figures already change with use: one maker calls for a weekly wash-down in daily use, and other makers’ stone intervals for commercial heaters shorten to every two or three months, or a set number of operating hours.

Hygiene, cleaning chemicals and staff safety in a commercial facility are matters for the operator’s work health and safety advice and the local council’s environmental health officer, and products should be approved by both the sauna or timber supplier and the chemical manufacturer. Our commercial guide covers hygiene, supervision and an operator checklist.

Signs an older sauna needs attention

Saunas age slowly, and the warning signs are easy to live with until they become a repair. If your sauna is ten or twenty years old, or you have bought a home with one already installed, look for these:

• Darkened or charred timber near the heater. Some darkening with age is normal. Timber that is blackening, charring or cracking near the heater is not. Harvia links it to safety distances, packed stones or elements showing between the stones. Why it matters: it means the timber is getting hotter than the heater’s clearances intend.
• Mould, rot or soft timber under the benches, behind backrests or at the base of the walls. Why it matters: it shows moisture isn’t drying out of the room, and soft timber can’t hold bench fixings.
• Loose, cracked or damaged benches, supports or fixings, or raised screw heads that get hot. Why it matters: benches carry people’s full weight in a hot room, and exposed metal fixings can burn skin.
• Crumbling stones, grit building up under the heater, or elements showing between the stones. Why it matters: broken-down stones choke the airflow, so the heater runs hotter and the elements wear faster. See sauna stones.
• Old or heat-damaged cabling or fittings you can see, such as brittle, discoloured or cracked cable sheaths, scorched light fittings or a damaged control. Why it matters: sauna wiring has to withstand far more heat than ordinary household wiring, and age and heat break it down. Don’t touch it.
• Slow heat-up, or water that no longer flashes to steam on the stones. Why it matters: it can point to an element that has failed, stones that have broken down or ventilation that has changed.
• Door or hinge problems, such as a door that drags, sticks, no longer closes on its own or has loose glass fittings. Why it matters: a sauna door must open easily outwards, and a gap lets the heat escape.
• A temperature sensor out of place, hanging loose, damaged or moved from where it was installed. Why it matters: the sensor controls the heater and protects against overheating, so a sensor in the wrong place can let the room run too hot or too cold.

The next step is to have the sauna inspected. Stop using it if you see charring, damaged cabling or a heater that won’t switch off. Electrical items, including the heater, control, sensor, cabling and light fittings, must be checked and repaired by a licensed electrician. Our troubleshooting guide explains common symptoms and their likely causes, and our service page explains how to request a service.

When to call a professional

Owners can look after the stones, the timber and the cleaning. Call a qualified technician, and stop using the room, if you notice:

• an element that doesn’t glow, a heater that heats noticeably more slowly, or an overheat protector or circuit breaker that keeps tripping;
• a heater that doesn’t stop when it is switched off or the timer ends;
• scorching, charring or rapid darkening of timber near the heater;
• elements that are bent, damaged or showing, or a burning smell that isn’t the first-use smell of a new heater;
• a damaged, loose or displaced sensor, or a control showing a fault code you can’t clear;
• loose glass fittings or a door that no longer closes properly;
• in a combi heater, water leaking from the reservoir or around the heater;
• in a steam room, fault codes, poor steam output, water where it shouldn’t be, or cracked sealant and grout;
• in an outdoor sauna, roof leaks, a base that holds water, or gaps between barrel staves that band adjustment doesn’t close.

Our service page explains how a service request works. BSC Wellness works with a dedicated electrical contractor, an independent business and a Harvia-authorised service agent, who carries out our electrical servicing.