You'd be forgiven for thinking otherwise, but saunas are actually quite easy to maintain and keep clean. Provided that you stick to some simple guidelines (and make sure others stick to them too!), it's mostly a matter of doing the right things after you use it.
The point of a sauna is to perspire, and if your post-sauna perspiration's left to run into the wooden benches, it will quickly stain them. This is likely to happen eventually anyway, but to slow the process down it’s best to sit or lie down on a towel to absorb the sweat.
Use liquids responsibly
Saunas should not need a drain. If there is water pooling on the floor, it's probably overflowing from your sauna heater; try not to pour so much on the rocks. Additionally, don’t use anything other than fresh water on the stones - especially chlorinated water from pools or spas, as this can release noxious fumes and corrode the heater. Adding a little scented oil to the water is fine, but other substances like beer or soft drink will leave burned sugar marks on the heater which are very difficult to remove.
Keep the door open
When not in use you should keep the door of the sauna open to allow it time to dry and air out. This prevents moisture settling in, which can lead to grime and bacteria build up, mould and rot. The non-slip flooring should be propped up so it too can air dry. Empty the bucket of water and stand it upside down when you're not using the sauna, especially if it's made of wood, as the water will soak into the timber.
How to clean sauna benches and sauna heaters
To remove bench stains, use a mild soapy water and soft cloth. This can also be used on the heater itself - just make sure the heater's off and completely cool when you clean it. Don’t use harsh or abrasive chemicals on benches, as these can bleach and warp the wood, ruining the grain and turning it grey. Specialist sauna cleaners are commercially available too. These are designed to be gentle on the wood, and will also give your sauna a pleasing fragrance. Keep the floor swept and mopped clean.
Cleaning the stones every so often is a good idea too, if you use scented oils. A mild detergent can be used - just wash, rinse and dry each one to rid it of oil residue.