Ever since I got started with welding, I've been doing all my hot work outside on my stone porch for fire resistance/safety. However, I've really gotten tired of lugging my tanks about 100' uphill from the shed/shop, and I really don't want to contemplate moving around the forge I'm building. The shed is large enough to work as a smithy as well (Is that going to be a problem? Should I just install a sawdust collector?), but it has a wooden plank floor, and I'm worried about fire resistance.
I'd rather save my money for steel and a nice anvil. What is the cheapest way I can install a functional, fireproof floor?
I've got about an inch of clearance to install the floor in before I start running awry of doors and such.