I tried to build some new kilns, but was unable to place them close to my other kilns, because the kiln would partially overlap the tile that the other kilns were built at, which were snowy. And of course I couldn't dig the snow away from the tile that they were on top of.
I think this is pretty bad, I have to wait in a worst case scenario, 1 week, until I can build more kilns?
Basically;: You should be able to build on top of snow tiles that have pavement under them.