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A Brief Intro to Zoning, Part 2

Updated: Nov 22, 2022

What is zoning, exactly? Why did it become what it is? Why is it important? Why is it so complex? How do we deal with it today? And how can I learn more?

This is our attempt to provide answers to those questions. It’s called: UrbanForm’s Brief Introduction to Zoning.

It’s organized into three sections:

The first part, "The Constitutionality of Zoning", can be found at this link.

This is the second of three parts, called:

The Complexity of Zoning

“Both building regulations and zoning were born out of concerns for public health: clean water, fresh air, effective sanitation, and so on. But political expediency and outmoded planning concerns drove many early regulations, and jurisdictions have spent a century applying band-aids to problems. We now have massively complicated regulations running to thousands of pages in length that require an army of experts to interpret and implement,” – Paddy Tillett, Principal and Director of Planning and Urban Design at ZGF Architects.

1920-22 Map of Euclid, Ohio, with the Ambler property in the top middle portion

Zoning in the US, as established in Euclid v. Ambler, generally groups land uses into the familiar, broad categories of residential, commercial, industrial, and agricultural. The Village of Euclid originally proposed a zoning system based on six different use classes and 3 different height classes.

Today, however, the uses allowed or prohibited are often embarrassingly specific. For instance, the City of Seattle explicitly allows or prohibits in certain zones “Railroad switchyards with a mechanized hump”, or “adult cabarets,” among 122 different use categories.

Crucially, an early distinction was made between single-family residential uses and multi-family uses (such as apartment buildings, townhouses, or other housing typologies). This distinction, according to authors such as Sonia Hirt and William Fischel, is perhaps the primary reason for the distinctly American consequences that currently surround zoning. This will be discussed in the third installment of this series (The Consequences of Zoning).

Even the first zoning ordinances that attempted to manage building form, such as the 1916 New York City zoning ordinance, were already quite complex. Remember, this ordinance was developed in order to prevent buildings of the size, scale, and shape exemplified by the Equitable Building. So formulas were used to mandate required step-backs at certain heights, giving rise to the famous ‘wedding-cake’ shape of NYC’s skyline.

An illustration by Hugh Ferriss

The formulas were complicated enough to prompt the commissioning of an illustrator, Hugh Ferriss, to help communicate the consequences of these rules. These illustrations were made famous by the book The Metropolis of Tomorrow, published in 1929.

Today, the methods developed to regulate building form are familiar to any architect. Height limits, setbacks/stepbacks, allowable ground coverage, maximum footprints, sloped planes, and other spatial constructs are all part of the zoning parameters that need to be discovered, calculated, modeled, and verified in order to design compliant buildings.

The density of building is also often regulated by specifying the minimum and the maximum number of dwelling units and the number of stories allowed. Allowable floor area is often expressed as a formula related to the size of the property, called floor-area-ratio (FAR).

This list of spatial rules is by no means exhaustive, and ever more specific mechanisms for controlling buildings are constantly being developed.

Diagrams illustrating various building regulations from the NYC Planning Dept

By combining land use regulations with other building restrictions, such as the formal regulations exemplified by the NYC zoning (sometimes called ‘development standards’), we arrive at what is commonly called ‘comprehensive zoning.’

Comprehensive zoning also governs things on or near buildings related to the urban environment, such as parking, landscaping, signage, canopies, and light fixtures, among many other things. Performance metrics for traffic, noise, pollution, and other things are also often regulated. Incentives, or bonuses, also become a common mechanism within zoning to allow modified building parameters in exchange for public amenities, such as affordable housing, park space, sidewalk or utility improvements, contributions to municipal funds, or other such concessions.

In the latter part of the Twentieth Century, partly in response to the perceived inadequacy of zoning on different levels and inspired by the thinking of Christopher Alexander and the New Urbanists, form-based building codes were developed. Form-based codes layered much more stringent and prescriptive building form regulations, on top of or blended with Euclidian use-based zoning, in the hopes that more and stricter regulations would better “foster predictable built results and a high-quality public realm by using physical form as the organizing principle for the code.” (

An example of implemented form-based codes from

Put all these land-use regulatory concepts together and you start to get a glimpse of The Complexity of Zoning, which is an inescapable feature of our building culture and built environment today in the US.

This Complexity means that a basic understanding of what you can build on a piece of land is actually really hard to come by. Layers of legislation on different aspects of the built environment keep being added; rarely do local political processes lead to reduction and simplification.

But there may be an even simpler and more effective way of giving people a glimpse into The Complexity of Zoning; by looking at how municipalities rule over something as simple as a parking spot.

If anyone doubts how complicated the rules for building could become, then the image above should put that doubt to rest.

And from here, it's also easy to see how a little bit of technology could go a long way towards making people's lives a little bit better. This is what UrbanForm does for the rules of zoning.

Zoning’s complexity is a direct result of the mashing together of US legislative processes and rules for the organization of urban space. Each on its own is complex enough; any architect knows that organizing, communicating, and documenting spatial ideas is hard, and any politician knows that balancing competing interests to write laws is no easy battle.

Zoning is both; it is the legislation of space, using the political process to manage buildings, space, and urban environments, by adopting ever more specific mechanisms, while balancing the many needs of both the public and the private.

Stay tuned for Part 3 of UrbanForm's Brief Introduction to Zoning, which is called: "The Consequences of Zoning."

Part 1, called "The Constitutionality of Zoning," can be found at this link.


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