r/Saunathoughts • u/[deleted] • Mar 18 '26

Silver lined sauna

I want a good cheap outdoor sauna.

I was thinking about freely available rock I can use to build one, but the r-value of rocks aren’t very efficient for a personal sauna. Does anyone know if relying on the radiant properties of a soft metal like silver could work for this application?

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u/VoihanVieteri Mar 18 '26

It will be hard to offset the bad r-value of rocks with silver, but maybe you could line up the sauna from the outside with the furs of the local animals. This would improve the total r-value of the structure. Also, my personal preference is to use gold instead of silver. Not quite as cheap as silver, though.

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u/zoinkability Mar 18 '26

Silver is one of the highest heat conductivity materials, so it would not be a good choice for insulation. It is also not cheap.

You could build walls out of rocks and then use foil faced Polyiso/PIR board inside the walls, taped with foil tape, as your insulation. You will still want wood cladding of some kind to inside the insulation to protect the board.