An overview of the tight housing supply in San Francisco hints at the influence of teardown McMansions:
Its residents have had much to grumble about in recent years: an influx of “monster houses” built by the well-heeled who buy, tear down and rebuild on lavish scale; a gaggle of Google buses and other shuttles that take techies to and from jobs in Silicon Valley.
Many Americans don’t like teardowns popping up next door. They typically take one smaller home and turn it into one larger home. But, do such homes restrict housing supply? Perhaps indirectly: (1) they bring in wealthier residents who likely don’t want multi-family housing and (2) they increase the value of the property meaning it would be more difficult to convert the same lot into multi-family housing. At the same time, McMansions could later be converted into multiple units (as proposed by some).
Generally, I would guess being for McMansions likely means being against affordable housing. Yet, the two subjects don’t have to be mutually exclusive.