Vietnam has a building typology known as tube housing.

It is characterized by narrow building frontages, often in the range of 3 to 4 meters, and multiple skinny levels. From what I've read, tube housing first appeared in the 17th century in cities like Hanoi. Its ubiquity over the years, however, has been aided by a myriad of factors, including Vietnam's transition from capitalism to socialism. This change meant that far fewer apartment buildings were being constructed, and so households had to take matters into their own hands and build what they could.

I've also read that this building type may have something to do with the way properties were taxed based on their frontage rather than their site area, though I haven’t been able to find a reliable source for this. Whatever the case, the end result is exactly what we discussed in this recent post — The 9-Step Rule: Why Simple, Narrow Buildings Are Good for Cities. Except with these frontages, it wouldn’t even take nine steps if the average building width is closer to 3–4 meters.

What is equally interesting about this housing type is that it represents a ground-up intervention (as opposed to the result of top-down urban design) and it is highly adaptable. It is not uncommon for additional floors to be added to these tube houses as needs change, and for the ground floors to serve as garages, living rooms, thriving commercial spaces, or as all three at once. It is an entirely flexible space that fuels entrepreneurship and allows households to make money.

Just think about how much easier it would be to open your own shop if you already owned the space. Conversely, how many of these ground-floor businesses wouldn’t exist if only there were a single line in the zoning regulations that said: “Nah, sorry, you can’t start and operate your own business here.” That is what I often worry about when it comes to land-use policy: what human potential are we quashing as a result of our decisions?