Q: Can you suggest a good wood for a sauna? Cedar is too expensive, redwood is out because of environmental concerns; and pine has too much resin that bleeds out? Perhaps spruce?

A: If I had a sauna, my primary concern would be splinters!

So, I would look for a splinter-less species. The ideal species is aspen. Because the sauna is so hot, decay fungi are killed, so there will be no risk of decay on the inside.

Aspen (and its related species) is odorless, splinterless, low cost, white, and commonly used for saunas throughout the world.