Can anyone tell me if untreated wood windows exist. I seem to remember hearing that before, but I can't find anything like that now.
Untreated wooden windows – do such windows exist?
Since wood windows cannot be left untreated, the profiles are usually treated (such as with pressure impregnation) during production. So you would have to go to a supplier who also manufactures windows specifically for heritage sites.
But all in all, I doubt you'll find what you're looking for in the industrial window market.