Setbacks and Land Consolidation
October 19, 2017

In the past I have talked about places and non-places. Places are the stuff that is "there" (such as parks, the inside of buildings, streets made for loitering), while non-places are the stuff that is dedicated to "getting there" and other fillers (roads, parking lots, setbacks, greenspace - a derogatory term I use to describe random strips of grass that are not parks, yards, or gardens.) We should care about this stuff because land is one of a city's most valuable assets, so we should not waste it. Modern cities tend to dedicate a large percentage of our land to non-places.

I have talked about the importance of granularity in our development pattern. A fine-grained development pattern diversifies land and property ownership which fights economic polarization (the growing gap between the haves and have-nots), forces good bones (a new property boundary every 40 feet means a door every 40 feet - this makes it much harder to build long blank walls), fills a streetscape with many destinations (actually having things within walking distance encourages people to walk), makes a place feel more intimate and human-scale, is easier to redevelop for the second generation of owners (it is easier to bulldoze and rebuild a small lot than an entire block), is less riskier (an abandoned or ugly building only ruins a single lot and not the entire block), etc. I could go on.

Modern zoning codes often require buildings to be setback from the property boundaries, and this is bad because it rewards land consolidation (creating a coarser-grained development pattern) and encourages the creation of non-places to fill the setback with. The smaller your lots are, the greater the percentage of land is that we have to reserve for the setback. Let's do the math and show an example. Let's imagine we have a 400x200 foot block with 10 foot set backs. We could plat the block in the following ways:

Number of lots Lot size Buildable area Buildable percentage  
1 80,000 sqft 68,400 sqft 85.5%
4 20,000 sqft 14,400 sqft 72%
8 10,000 sqft 6,400 sqft 64%
32 2,500 sqft 400 sqft 16%

We can see that setbacks result in smaller lots having less usable buildable space. Small lots - the main ingredient of fine-grained urbanism - are just silly when 56 of the land has to sit empty. When land values go up, land is more valuable, so we want to waste less of it. Thus, setbacks motivate us to consolidate land into fewer lots. Pretty quickly we will be incentivized to cover entire blocks in single buildings.

Setbacks are bad economically, but we can also touch on aesthetics. I love the sense of cosiness and enclosure that comes from a continuous streetscape without gaps, especially when the streets are slightly crooked with the odd terminating vista to capture the imagination, and perhaps a few street trees to provide a canopy to soften the sunlight.

A streetscape without setbacks in West Village, New York.

It is the same sense of enclosure and human-scale-ness that you get when you are strolling through a park, following a trail beneath a lush canopy that winds around the trees wondering if you are going to stumble upon a small surprise such as a waterfall or a small stone bridge crossing over a creek.

A trail winding through New York's Central Park.

Setbacks are not a substitute for building real parks or making our cities environmental sustainability. Setbacks do not make a place safer (modern building codes require fire proof party walls) nor do anything for public health (modern sanitation like indoor plumbing and flush toilets have eliminated most historically urban diseases.) Instead, setbacks are bad economically as they force us to consume more land than needed and encourage land consolidation, they break the sense of enclosure on urban streets, and space our built environment out - making us travel farther to get places. If a home owner owns a large parcel of land and wants to build a house back from the property boundary, that should be their call. But, we should not require every building to be set back some arbitrary distance from one another because of all of the negative-side effects discussed above that come with it. Let's get rid of minimum setback requirements. 

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James Lukacovic • 10.24.2017 • 12:08 PM (MDT)
While I mostly agree with your consensus here, I suppose the counterpoint would be ensuring solar access.  This is increasingly important for energy production at the point of use, as well as traditional concerns of light/air.  For example I think Christopher Alexander has quite a few patterns about humans finding the most comfort in spaces with cross breezes and light from more than one direction.  These could be addressed by different means, such as courtyards, single side setbacks(Charleston pattern).  For solar access some sort of solar envelope restriction based on latitude so that you can not shade more than a certain percentage of your neighbors property for example. To bring it back to a current Strong Towns topic, merely eliminating setbacks is a simple solution to a complex problem.  zoning for what you want may only be a complicated problem, provided you are willing to specify and enforce a particular vision.  Though as a whole cities are complex adaptive systems which will react to stimulus in ways that you may not be able to anticipate. This is what makes cities so fun, yet frustrating at the same time.   As a technical note, the jurisdictions that I am most familiar with side setbacks are treated as a percentage of total lot width, often with upper an lower bounds.  this again varies by zoning/use district which is another discussion.