“Density without ripping out single-family housing.” That’s how one proponent described new rules that would allow some Seattle homeowners to turn detached garages or other backyard structures into apartments.

It’s a great idea. Putting an apartment in your back yard can let your neighborhood accomodate new residents without changing its character. From the street, the neighborhood looks the same; the only change is that more people get to enjoy it.

And adding residents has a couple of nifty benefits. First, the rules could help keep housing affordable, both by increasing the supply of rental housing (which helps hold down rents) and by giving some homeowners an additional source of income (which can help them meet their mortgage payments).

And second, denser neighborhoods—at least as a general rule—are able to support local stores and services. Higher residential density helps make transit cost effective, and also increases the number of local patrons for shops and restaurants.

  • For some reason, rising density sometimes gets blamed for causing high housing prices. That’s completely backwards. Rising density is typically a consequence, not a cause, of rising housing prices. As demand for housing goes up, housing prices go up too; and the housing market responds by trying to create more places for people to live. (I know, I’m anthropomorphising. Sue me.) If anything, failing to densify—that is, creating zoning rules that prevent the housing market from responding to high prices—is what makes housing unaffordable.

    By easing zoning restrictions, Seattle’s rules let the market do what it does best: respond to demand.

    Of course, people are concerned that new residents will undermine quality of life in their neighborhood—by boosting traffic, taking up parking spots, and adding transient renters to an established neighborhood of homeowners. The real fear is here is change—which is a fear I definitely understand.

    But it seems to me that many of the changes that happen when a neighborhood accepts new residents are good ones. New faces, new businesses, new transportation options—on balance, these are things that make a good neighborhood even better. I’m not sure there’s really much to fear here.