A setback is the minimum distance that a building is required by local law to be set back from the edges of whatever piece of private property it sits on. These requirements are a common feature of modern zoning codes, and may vary by the location and type of building. You can have side, rear, and front setbacks.
Here's an illustration by Sarah Kobos (from this popular Strong Towns article, "Kick The Tires on Your Local Zoning Code") that shows what each type of setback might look like on the site plan for an individual piece of property, and how setbacks reduce the portion of the lot that a building itself can cover:
Setbacks in the Traditional Development Pattern
In the traditional development pattern, front setbacks are usually rare to nonexistent, at least on main streets / commercial streets. This is true worldwide: check out this photo essay by Johnny Sanphillippo for examples of the same basic development pattern, in which buildings hug walkable streets, from Japan to Turkey to America.
This became the case for a few reasons:
- Traditional development makes productive use of scarce land. This has been important for much of human history, when cities were compact because they were scaled to people who walked. It is only very recently that our society has had the technology (the automobile) and the ability to accrue debt to expand our cities and their infrastructure outward at an unprecedented rate—what Strong Towns calls the suburban experiment.
- Traditional development tends to be small-scale (or "granular" - read about that here) with the city subdivided into very small lots. On a small lot, even a modest setback can dramatically reduce the amount of land you're allowed to build on.
- True, required setbacks can lead to beautiful front gardens or patios. But they can also lead to non-places, like a barren expanse of grass that isn't used by either the property owner or the public. Here's an essential essay by Andrew Price explaining the concept of non-places, which add no value but push the locations humans actually want to spend time farther apart from each other.
- In a pedestrian-oriented business district, local shop owners want customers on the sidewalk to be enticed into the store. What better way than to have them walk right by the windows, where they can look inside?
- Architects and urban designers talk about the psychological benefit of having no setbacks: it causes a continuous row of buildings to "frame" the street, which creates a sense of enclosure, like you're in an outdoor living room—as this photo from Puebla, Mexico illustrates. This is a type of environment that most people find instinctively comforting and interesting to walk through.
- Deeper setbacks can cause a pedestrian on the sidewalk to feel exposed, especially if there's also traffic to worry about.
- Eliminating the front setback alone won't make a street walkable. You also need a stimulating environment with frequent front doors (a high Gehl Door Average) or other activity, not long, monotonous walls as in this photo of a pedestrian-unfriendly Trader Joe's:
What About in Residential Areas?
In residential areas, front and side setbacks are more common even in traditional, pre-car development—think of this row of Victorian houses:
But it's also common not to have any side setback, as in these Montreal row houses:
This contributes to the same urban-design benefit as on a commercial main street: a continuous "street wall" of buildings framing the public space of the sidewalk / street, leading to a pleasant and secure feeling of enclosure.
What a Setback is Not
A common source of confusion about front setbacks is the notion that a zero setback—buildings that come right up to the front property line—means a narrow sidewalk. These are two completely separate things. An urban sidewalk almost always falls within the public right-of-way, which means if the sidewalk is narrow, the solution is to narrow the driving lanes and give more of that space over to sidewalk.
Consider these Washington, DC row houses:
The problem with this street is not that the setback is too small—i.e. that the houses should have deeper front yards. The problem is that the road is too wide and the sidewalk too narrow, and people using the sidewalk are not protected from high-speed traffic whizzing by them. The solution is to narrow the adjacent roadway, widen the sidewalk, and add a buffer like street trees or parallel parking to protect people on foot from traffic.
Here's a set of row houses on a much nicer sidewalk with about the same setback:
Understanding When Setbacks Are And Aren't Appropriate
There is no one-size-fits-all rule against setbacks in cities. They are certainly appropriate in more suburban areas where a verdant look is desired. (Here's a bit more on their history in the U.S.) And they're appropriate for potential nuisance uses—an airport runway shouldn't come right up to the edge of the airport property!
But for walkable main streets, a lack of setbacks represents the tried-and-true wisdom of many centuries.
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