With Texas weather, you could probably do okay with the housing, although it's a bit small for the amount of birds you want. Would the nest boxes be external, so you don't lose any more floor space???? However, you really should consider at least 10sq. ft. of run space if your birds are LF rather than bantams. Something you might want to consider with the height is the roost issue. Will you be able to give adequate headroom for hopping up onto the roost without losing floor space? I guess 18 and 18 would work though, if it's three feet high where the roosts would go...