One solution to housing affordability proposed by Yimbys is mid rises and missing middle housing (mostly small apartment buildings like 2 plexs and 4 plexs). The problem with such buildings is that the price of land is such that they would be uneconomical in much of the US. For infill development a 2 plex wouldn’t generate much more profit at all than single family homes in many instances and thus unlikely to be built even if legalized. Many missing middle housing options would really only be viable if they were greenfield rather than infill.
Places that have legalized missing middle have seen only modest increases in construction
To make a meaningful impact on prices you need much more construction. According to Yimby studies you need a 10% increase in development to have a 1% reduction in rents. Development on that large of a scale in big cities requires high rises.
Contrary to popular belief there isn’t a gigantic construction cost per square foot difference between low rise, mid rise and high rise.
The cost of an elevator makes mid rises less economical than high rises and low rises.
From: Edge City: Life on the New Frontier, by: Joel Garreau
“Residential structures either have to be less than three stories above the main entrance, in order for you to build them without elevators, or they have to be high-rise. Once you start building a residential structure of concrete and steel to accommodate an elevator, your costs kick into so much higher an orbit that you have to build vastly more dwelling units per acre in order to make any money.”
The price of land is so high in many markets, that only high rises are economical.
One study found that in order to have a break even rent of about 2,300 per month, you would need 12 floors in San Francisco. Shorter buildings would require rents of 4,000 a month or higher. Source: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3674181 Edward Glaeser argues that much taller buildings are needed to make NYC affordable
“In New York City, the price of building an additional square foot of living space on the top of a tall building is less than $400. Prices do rise substantially in ultratall buildings, say over fifty stories, but for ordinary skyscrapers, it doesn’t cost more than $500,000 to put up a nice, new 1,200-square-foot apartment. The land costs something, but in a forty-story building, a 1,200-square-foot unit is only using 30 square feet of Manhattan, less than a thousandth of an acre. At those heights, the land costs become pretty small. If there were no rules restricting new construction, then prices would eventually come down to somewhere near construction costs, about a half million dollars for a new apartment. That’s a lot more than the $200,000 that it costs to put up a nice 2,500-square-foot house in Houston but a lot less than the $1 million or more that such an apartment now costs in New York”
In my view any high priced parcel of land should be 40 floors by right