by Procraft
A cedar sauna needs very little upkeep. The main rule is to let it dry out fully after every use. Keep the benches and floor clean, air the room out, wipe up sweat and spills, and leave the door open to dry between sessions. Do not varnish or seal the inside. Cedar is meant to breathe.
Leave the interior cedar bare. A varnish or sealer traps moisture, gets hot and sticky, and takes away the aroma and feel that made you choose cedar in the first place. Clean wood that is allowed to dry looks after itself. If you want to protect the benches, a dedicated sauna-safe paraffin oil made for that purpose is the only thing to consider, and even that is optional.
The outside of an outdoor sauna is a different story from the inside. Left bare, the exterior cedar weathers to a silver-grey, which is only a surface change. If you want to hold the warm brown tone, an exterior wood finish on the outside faces will slow it down. That is a choice about looks, not something the wood needs to survive.
Western red cedar resists rot and moisture on its own, so a clean sauna that is allowed to breathe and dry will last a very long time with just this light routine. There is more on the wood itself on our Western red cedar page.
Procraft builds Western red cedar saunas and makes four CSA-approved electric sauna heaters, from 4.5kW to 9kW. See the heaters, read about Western red cedar, or learn how our installations work.