Towards 'Dynamic' Zoning

Don Elliott, author of A Better Way to Zone, argues that dynamic zoning regulations can help cities grow appropriately and avoid bottlenecks to good development.

 Don ElliottEver since the first zoning ordinances were adopted over 90 years ago we have thought of zoning rules as "fixed" – at least until City Council acted to change them. Minimum lot sizes, building heights, and setbacks were written down for each district, and they didn't change without Council action. A 35 foot height limit was a 35 foot height limit until Council amended the ordinance to make it 45 feet. Obviously, this made zoning predictable, but it also made the rules rigid, and most zoning codes are filled with "fixed" rules adopted by some long-dead City Council that no longer make sense. In fact, much of the history of zoning can be seen as a dance (or a battle) between the desire for flexibility and predictability. Fixed rules are predictable at the expense of flexibility.

But local zoning rules don't have to be fixed – we can design them to change with the times in those neighborhoods where change is wanted. In fact, we are used to adopting standards that change. Many cities adopt impact fees with escalator clauses – they don't require City Council to adopt a new fee each year, they just state that the fee will go up by the construction cost index. We don't know what the fee will be next year, but we know it will be determined in an objective way.

An example of contextual height limits.
An example of contextual height limits.

Similarly, an increasing number of zoning ordinances include "contextual" height limits – the maximum height on your property is equal to the tallest building on an adjacent site, or on your block face, or within a certain radius of your property, or one story taller than that height. Contextual height limits reflect the Council's desire that buildings "fit in" with their neighbors, or that the neighborhood gradually allow taller buildings, rather than setting a fixed maximum height. After all, many cities have a single zone district with blocks of predominantly one-story houses and other blocks of predominantly two-story houses. Rather than create two districts with two different maximum heights, Council defines the maximum height based on the surrounding context. But note that these contextual maximum building heights may change over time without further Council action. If someone builds a new building one story taller than its neighbors, that changes the context for nearby properties, and they may be allowed to build even taller buildings. That is a "dynamic" zoning standard, and I believe we will see more of them in the future.

Obviously, dynamic zoning standards are not appropriate everywhere. Most single-family residential zones are drafted for very high levels of predictability and homeowners often prefer an absolute height limit to one that may change in the future. But in redevelopment areas, mixed use areas, transit-oriented locations, and others, dynamic zoning standards have two significant advantages that some cities will find attractive.

Dynamic zoning in action.
Dynamic zoning in action.

First, they acknowledge the facts that cities change and that in some areas of the city the flexibility to respond to market forces (within limits) is more important than maintaining a pre-determined form, scale, or character. Dynamic zoning standards can allow more flexible development while still ensuring that the resulting projects are not significantly out of scale or character with those around them. While some cities may address these types of transitional redevelopment areas through form-based zoning (which is also based on a fixed graphic depiction of a preferred building form), others will decide that there are areas where flexibility is more important than form.

Second, dynamic development standards can help avoid some of the NIMBY battles that plague efforts to redevelop and densify transitional areas. While zoning theory says that Council will amend zoning when needed to reflect changing market conditions or planning goals, in fact that is only partially true. Good planning around many a light rail line or multi-family residential area have been stymied by those who oppose any change in the neighborhood no matter what its positive impacts on traffic congestion, air quality, housing affordability, or economic growth. Dynamic development standards allow Council to establish triggers that will permit gradual diversification of land uses or increases in development densities and scale over time without requiring a separate hearing (and NIMBY battle) on each project.

For both of these reasons I believe American cities will move towards more dynamic zoning standards in some redevelopment and transitional areas. Like many other things in life, sometimes the best way to get a better zoning result is to lighten up.

Donald L. Elliott is a Senior Consultant with Clarion Associates in Denver, Colorado and the author of A Better Way to Zone (Island Press 2008). He has assisted over 40 communities throughout the U.S., Canada, Russia, Indonesia, and India to reform and modernize land use regulations.




I struggle with balancing predictability and flexibility. Rigid standards protect property rights, yet stifle innovation and adaptability. Flexibility seems too often a game of who-you-know. I'm still thinking through many of the points in Don's book, A Better Way To Zone. There's some good stuff to think about there.

Flexibility Thoughts

I agree with you that this is a struggle, but would argue that rigid standards don't actually protect property rights (unless you count the ability to dictate what others can do with their property as your "right"). Rigid standards do protect (and often artifically increase) property values though. As governments appropriated the absolute right to dictate what you can and cannot do with your property (whether by choice or by force, the "we know what's best for you" argument... a later conversation of course) changing the rules has to be a game of who you know... there's simply no other way to get it done. There has to be a better way to allow individual choices and creativity to flourish without making every choice subject to the wills of politicians (and their susceptability to bribery). I would favor eliminating zoning and using nuisance laws for flagrant violations (as it was before zoning), but dynamic zoning, or something akin, would be an acceptable compromise to at least return some power to the individual in terms of property rights while allowing others the social safety net of some zoning. Thanks for mentioning the book as I am now going to get my hands on a copy.

Fixed zoning may not be broken

This argument seems to be predicated on the assumption that higher is necessarily better, and that there should be a way to change the streetscape without asking the opinion of neighbors because they are wrong. I can understand the frustration of builders who think that Council and nearby residents will stifle progress unless their hands are tied, but this is the frustrating nature of democracy.

There may be very good well thought out reasons for the height limits, including sunlight, the benefits of wood frame construction, consistency with built heritage, the framing of public space, or having an appropriate ratio of different household sizes. Automatic bonusing is inconsistent with planning and disrespectful of those who put effort into the plan. It is also an excellent way to repeat and exacerbate planning mistakes. Every "transitional area" (or areas owned by speculators) has at least one inappropriate building whose approval ended someone's career. Under this scheme, this mistake becomes the new standard.

While I see the advantage to a "generative code" like the one proposed by Christopher Alexander this is a far cry from automatic upzoning. A generative code can as easily reduce the building mass as increase it, because its purpose is not to increase the leasable floor space when land prices increase, but to shape the public realm through positive space in the context of what is already there.

The reality is that areas whose zoning has not changed in a long time, like Georgetown in DC for example, can have more intensity than areas with more permissive and flexible zoning.

This does not change my point of view that there should be no residential zone that forbids 3-story or semi-detached houses, but the transitional areas with development pressure are the ones where Council needs to be firm that planning, not prices, determines how the area will evolve.

Urban Systems

I've come to view urban systems akin to ecological systems - change occurs to the built form because there are societal or economic needs, opportunities and pressures that are asking to be met. While not all change is beneficial, I would argue that if land prices are increasing and developers are clamoring to build higher in response to pressure for urban housing at the core or a city or town (and not due purely to speculation), that this is telling us something, that there is a need that should somehow be facilitated rather than stymied by zoning. In this view, zoning as facilitator is about setting standards for quality form, appropriate locations, mitigating REAL impacts (not the imaginations of NIMBY's) & etc., not about protecting the status quo. Likewise if there is demand in a neighborhood for a walkable corner store, coffeeshop, hair dresser, rental accessory units, or even a neighborhood pub (depending on your views on these things), should zoning simply stand in the way of these "undesirable uses"? It's a complicated equation, but ultimately if cities and neighborhoods are to remain vibrant, I think change and evolution are the order of the day and its the job of zoning to facilitate this change in an appropriate manner.

I'll put my foot in my mouth when someone asks about demand for more auto-oriented big-box stores along arterials, but I think both New Urbanists and Market Urbanists have looked at this chicken-and-egg problem, with our past zoning and infrastructure choices dictating demand.

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