While it’s now legal to build multiple units on land previously zoned for single-family residences (SFRs), the cost of construction is still high. The costs of acquiring a site, making sure to conform to environmental codes, and building from scratch definitely add up. Builders aren’t able to work out a positive return on investment for new constructions.
They can cut a lot of the costs by using existing structures and renovating them. But, many of these structures are zoned for commercial use only. There are certainly zones that can be commercial or residential as needed, but not nearly enough to satisfy buyer demand. New zoning laws in the Los Angeles metro area and in the San Francisco Bay Area have facilitated conversions from commercial to residential, but even that isn’t enough. And in areas without these new policies, such as the San Diego and Sacramento metro areas, conversion rates are dramatically lower.