"Builders usually pack in two or three bedrooms, stacked in two or
three stories. Size typically ranges from 1,000 to 2,000 square feet,
allowing for a spacious living room and kitchen on an open floor plan.
The homes are clustered in mini-communities, a modern twist on L.A.'s
famed bungalow courts. There are no shared walls, but neighbors are
separated by mere inches. Developers enclose the miniature gap between
the homes to keep out water and unwanted critters, giving the impression
of town houses.
Such projects grow from a 2005 Los Angeles city
ordinance that aimed to add more affordable for-sale housing — at least
by L.A. standards — in densely packed neighborhoods. It lets developers
carve up a lot zoned for multi-family use into small single-family
plots, allowing multiple homes with separate foundations. The
regulations chopped the minimum single-family lot size in those areas
from 5,000 square feet to 600 square feet. The city of Glendale is now
considering a similar ordinance."
I'm amazed how many tiny houses there are here in my home town of Rapid City, South Dakota. I looked at one 400 square foot house for sale that eventually sold for about $40,000. There are many a bit bigger than that scattered all over.
Personally I think 800 square feet is about right for a single person, and maybe 1000 for a couple. Throw in kids and who knows. Savings on congestion, heating and cooling, etc.