Regulations often result in unintended consequences. Money flows to find any crack in the system, after all, and often those cracks are in very odd places. Zoning and building codes are no different, and they can manipulate not just how people do business but how we built our cities. In Marin, towns regulate density through a few different rules. Most prominent is units per acre, sometimes around 20 to 30 units per acre, but Marin’s various codes use other measures: floor-area ratio, parking minimums, minimum lot sizes, height limits, and minimum amount of open space.

Last month, the blog Urban Kchoze looked at this panoply of regulatory systems to illustrate how they alter the built environment, and found that they often don’t do a very good job of limiting traffic or population density. About Marin’s favorite regulation, units per acre, the author writes:

An interesting point to consider is what happens to the single individuals in North America that seek cheap housing options, since they are largely deprived of the small 1-Bedroom apartments due to regulations restricting the number of units that can be built per area? Well, they share apartments with roommates. Indeed, becoming roommates is the way consumers have devised to go around the excessive parking and density limitations imposed by North American planners. It is not a desirable situation, but when in a pinch, people will do it.

So North American regulations that limit the density of units but are less restrictive on FAR will result in bigger housing units as developers will build big units to maximize profits.

Policies that do the opposite, meaning limit FAR but are favorable to subdividing buildings in many units thanks to a lack of minimum lot size and low or no minimum parking regulation will have the opposite effect: tend to increase housing density but reduce the size of units.

Our current system doesn’t work very well. Rents are spiking, people are aging, traffic is growing, and the poor are crowding into tiny spaces, especially in The Canal.

As Marin continues to wrestle with the future of its town centers, especially in downtown San Rafael, leaders should figure out what exactly they want to limit. If it’s traffic, they should limit parking. If it’s kids for the school system, they should limit height but lift density caps. (Small homes don’t accommodate families well, after all.)

Marin needs to chart a way forward, but the only way to do that is to understand where we want to go, and what tools we need to get there.