Minecraft wiki entry for Roof_types, associated text: One of the most basic green roof structures. House types like this function well for the first few nights a player is surviving.
A roughly circular mound of dirt, hollowed out, and with a door and crude windows inserted. The windows are very deeply inset.
A wooden frame, built and then buried; the windows and doorway are still quite deeply inset.
A much neater design, similar to the church at Hof in Iceland.