I'm not exactly sure which materials other than planks but when you try to build it, if you don't have the right materials, it'll tell you.
I'm still having issues unable to place down foundation. I leave the game then go back to get rid of the little bug.
You need to hold the right mouse button and build posts and stairs. every post allows floor expansion of 3x3. For the floors you hold right mouse button and use floors.
