using recycled hardwood floor planks

Am thinking of building a FIR (Far-Infrared-Sauna) into an attic space, with a door opening out to a over-the-garage room, both of which have low ceilings. Am I right that you are not supposed to "lie down" or recline in a FIR (Far-Infrared-Sauna) sauna?

Also, since I have MCS, Candida, and multiple food allergies I have to be super careful about construction materials. Does anyone have thoughts about using the recylced hardwood floor planks (that are taken out of teardown houses for re-use as hardwood floor in other houses) as long as all of the stain and polyurethane has been sanded off? I'm pretty sure that the stain and topcoat and confined to the uppermost skin of the wood and can be successfully sanded off.

If this seems viable, then it would be a very inexpensive way to get the cedar plank look and not have off-gassing. Tweet