Mezzanine
My mezzanine was built by a local builder and is built out of 4x4 steel posts with steel floor joists. Half is for storage and half is finished with carpetting, painted walls, two love seats and A/C. The stairway is made out of 4x4 studs and is as solid as the stairs in your house. He pulled a building permit and had it inspected by a local Florida building inspector. The next hurricane may demollish my hangar but the mezzanine will still be standing. Cosmetically it's not that beautiful so after my next airplane project, I might dress it up a bit.
I'll post pictures. If you need more detail, PM me.
Bill Near