Hi Matt,
I did a remodel on a 10 year old wood fired sauna. Problems were>
- Original structure had no stub (stem) walls on top of Concrete slab floor to keep wood above floor level. Everything had rot because a Sauna has huge amounts of condensate inside.... even more with with a wood fired.
- The stove access door was located inside of sauna.... thus ashes, wood, had to be carried through the entry door and made a huge mess. We converted to a unit with firebox access on outside of building.
- Had to add external combustion air port through the masonry wall because whomever build it forgot to do so.
- Interior surface has to be water proof on an outside free standing installation in order to keep the walls from absorbing way too much condensate..... unless you plan to keep it fired all winter long. The mold that grows deep in the walls is really hard to get rid of.
Most Saunas are wood lined and if I were going to do one new from scratch I would make sure there is stringers behind the wood with vents at top and bottom of each stud cavity.
We later added a vent in the ceiling for fair weather times to "Air Out" the inside in good weather.
And finally.... the Electrics/Controls.... Make sure to buy the absolute best damper, thermostat and air control you can get. Make sure it has a safety "fail safe" for "Over-Temp". Wood burning is very hard to regulate and the inside temp can be deadly if not closely regulated. It is no longer legal in my state to use wood fuel for a sauna or steam bath. Also..... though likely not relevant, they are not allowed on many Homeowner Policy's.
As an extra safety device I added an audible alarm for 130 degrees F (Wet Sauna) just in case all else failed and the owners fell asleep....
Good luck with your project.
Judd
