Just some flooring options I found while messing around:
The graphite one to the left is the University sign flipped and tiled. The white tile is spillway planters flipped. The weird pattern one is hotel planter flipped and tiled. unfortunately that's the only way they seem to want to fit together :/
oh and the guy that made 512 warehouse is a legend. using the rusted roofing of team HQ as a roof for a warehouse is a good idea.