McMansions may not just be undesirable on their own. If a McMansion is built, another kind of dwelling is not. One proposal in San Francisco aims to address this:

He will introduce an ordinance making it much harder to build giant homes — the ones increasingly dotting the hillsides above Glen Park that many San Franciscans deride as monster homes or McMansions, but which are perfectly legal to build.

He will also ask the city attorney to draft legislation making it legal for any corner lot in the city that’s currently slated for one home to allow up to four units. And, most significantly, the legislation will allow any parcel within a half mile of a major transit stop like the Glen Park BART Station to be converted into a fourplex — corner property or not. The extra units could be rented or sold.

Yes, in large swaths of San Francisco — this supposedly progressive bastion — it’s currently legal to build an enormous, over-the-top house for one family, but illegal to build a small apartment building of the same size for four families.

This question plagues many desirable neighborhoods in big cities and suburbs: should anything that disturbs the existing character and/or property values be allowed? If this is the driving question, a McMansion might be a threat because it is a different kind of home – derided by critics as too big, architecturally incoherent – compared to what is already there. At the same time, the McMansion is still a single-family home. If that single-family home was replaced by a multi-family unit, residents then express concerns about increasing densities. They might also have concerns about renters moving into what was a neighborhood of homeowners as many Americans assume renters are less committed to their community.

And, as the article notes, making changes like this often means neighborhood by neighborhood conversations to consider the implications. Will a change have different impacts in different communities? What might be some of the unintended consequences? What will neighborhoods look like in a few decades with changes?

San Francisco may have a particular need for solutions but so do many other locations. The answers might come slowly on a case-by-case basis.