From all maps I have seen, the smith is always drawn as a simple house, with a chimney for the furnace and eventually some area for him to work with the Anvil.

As for the Sawmill I think a big common house would do it, like a Warehouse, with enough space to the workers cut and prepare the wood, as so to stock for future use. I've read some about those techniques and I don't remember anything about using Water or Wind force to do the work. All they used was fire (furnace) and human force, to cut the wood or hammer the iron.