There is currently a very wide range of houses on the hems (lanes) of our district of Thành Phố (City) Hồ Chí Minh. To some degree, this is tied to the economic levels of the residents. This area is a relatively new area of HCMC, dating back to squatter shacks in the American war years. I administered a construction contract to a Vietnamese contractor in 1972 to build an underground storm water drainage tunnel through this neighborhood, and most of the houses in the neighborhood were either wood posts and grass thatch, or corrugated metal.
There are still some vestiges of the old squatter shacks around, but most have been replaced over the past thirty years with houses constructed of reinforced concrete frames with hollow-clay-tile block infill.
Since the squatter shacks were thrown up haphazardly, the plots of land they occupied were irregular and therefore the hẻm (lane) had no smooth right-of-way. The hems went everywhich way to provide access to each shack. As you look down into the hem today from my rooftop, or walk along the hems, you can see the legacy of this indiscriminate lack of planning. It appears to me that the lot lines have since been formalized based on the haphazard shapes of the shacks occupying the land.
Thus today's houses do not usually have parallel sides -- the corners are at odd angles. The house we occupy now is 3.66 meters wide at the front, and 4.25 meters wide at the back. Notice the middle-class house under construction in the photo below (click on the photo to expand it):
It bends around the white house next to it, which in turn has an even odder shape. This new house is now almost complete at four stories, and is very typical for a middle class house in the inner city of TP. Hồ Chí Minh today. It has around 120 square meters in area, or 1,300 square feet. It is likely that an extended family of a dozen people will occupy this house.
Some lots are very small at 9 square meters, like this one-story house in the photo below:
This house is occupied by an older woman who sells small grocery items out of the front door. Like many Vietnamese, she sleeps on the floor at night. Many houses like this are being bought up in combination with adjacent lots for construction of larger middle-class houses as the economy grows rapidly here in Viet Nam.
Other lot owners simply build on what they have, like this three-story small house on a 15 square meter area plot.
The middle story has no windows and is used as a bedroom with sleeping on the floor. This house is occupied by an family of four.
By comparison, the standard San Francisco lot at 25-feet wide and 100-feet long is 232 square meters in area, and that is low for most American cities and towns.