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Zoning Terminology

Ann Arbor City Council Member Sabra Briere circulated the following discussion of zoning terms. Council Member Briere later explained "I tried really hard to write definitions of the current thinking being used for these terms.  I wasn't trying to give my own definitions, and of course, I am always open to refinements.  But if we don't all understand what the current 'planning' meaning for these terms is, then we're talking at cross purposes."

We thank her for her effort to begin the dialog with an exploration of the terms being used.


This is an attempt to define some of the terms most often used in Ann Arbor when we discuss planning.  It’s also the beginning of a longer document that will describe the history of the most recent efforts to create a new vision of Ann Arbor for the 21st Century.

I came to Council after all but the R4C / R2A study committees were not only underway, but nearly completed. 

The A2D2 (Ann Arbor Discovering Downtown) committees were appointed and working for several years before I was elected; my input was very limited.  I was asked a few questions about historic preservation, and attended several public meetings.

There was no citizen involvement in the Area, Height and Placement work prior to the current public meetings.  All the work was done by the Planning staff.  Some prior meetings were held with ‘stakeholders’ – but the Planning staff consider those stakeholders to be business and development interests.  Council members insisted that the public be allowed more input after the Planning Commission had already recommended approval of this major rezoning.

The R4C /R2A study committee will be appointed, perhaps as early as next Thursday.  This history of this committee is unwritten, but it was established in March, 2009.  We’re still working out the details.  Right now, it focuses on the Central Area, and looks at two zoning districts: R4C and R2A.

All of these committees rely on Planning staff members for guidance.  The A2D2 committee used outside consultants for leadership and lots of ‘community input’; the Area, Height and Placement rezoning was primarily the work of the Planning staff.  The R4C/R2A study committee’s format is less clear to me, although I’ve read the committee’s charge.

First, a little dictionary of terms.

As we talk about planning, it’s very easy to fall into planning jargon.  Here’s the definition of terms as I’m learning them:

A2D2 – Ann Arbor Discovering Downtown

This coinage implies that none of us really knew where and what downtown was or could be.  I’m certain that’s a mistake, but it was supposed to be memorable.  Some members of Council still get this confused with the robot from Star Wars (R2D2) – which is very funny.  However, the background for this project was that:

(a) Ann Arbor made downtown development too confusing and difficult for developers.  There were many different zoning areas (C2A, C2A/R, C2B, C2B/R[1]), and nearly all of them were considered so out of date with the current expectation for downtown development that developers were encouraged to request Planned Unit Developments (PUDs) in order to build anything downtown.  This required extra steps, more cost, and was riskier for developers.

(b) Because developers weren’t designing buildings to fit the zoning downtown, anyway, no one knew what to expect.  This created real problems for matching the Downtown Plan (see Area Master Plans).  It was clear that the vision in our downtown plan needed to be reconsidered, as did the zoning of the downtown (DDA) areas. 

Additionally, the A2D2 process focused on incentives to increase downtown housing.  Increased residential density was one of the major planks of the overall program for an improved, modern Ann Arbor.  Now that the A2D2 process in nearly complete, we are waiting for the economy to improve to see what new development will really look like.  An expectation is that PUDs will no longer be encouraged in the downtown area.

Age Gap

Ann Arbor will always have an influx of young people as long as the University of Michigan is here.  Recent studies have also shown that it’s a great place for retirees.  However, there are many who worry that it’s not as attractive to those in their 20s and 30s.  The argument is that the housing in the ‘suburban’ residential areas is too settled to attract young, unmarried professionals, and far too expensive.  Housing in the near-downtown areas is too student-centric – it’s often poorly maintained, expensive enough to require roommates, and is a student ghetto.  There’s nothing in between for the young person just out of college, in their first (or second) job.  There’s also nothing for the ‘creative class’ that sings, creates music, makes art, acts, etc., while working in one of the lower-wage jobs to pay the rent.  These people in their 20s and 30s, we hear, either leave town or leave the state altogether.

When housing for ‘young professionals’ or ‘creative class’ or ‘work force’ is proposed, it is frequently opposed by the residents of the neighborhoods that would otherwise welcome the people as their new neighbors.  The opposition – as I’ve observed – breaks down in a couple of ways: concern over demolishing existing buildings (infill development); and concern because the development disregards the existing residential look and feel –scale and nature – of the neighborhood.

Area, Height, and Placement (AHP)

This zoning language is used in every zoning definition to define the location; front, rear and side setbacks; massing; and maximum height allowed in that development zone.  However, it is specifically being used to refer to redefine the zoning codes for the following zoningdistricts:  C1, C1B, C3, M1, M1A, O, R1C, R3, R4B, R2B, R5, R6, RE (see Zoning).  The Area, Height and Placement rezoning project was, I believe, initiated by Council and implemented by the staff.  The purpose was to make sense of all the various area master plans, bring them more into the 21st Century, align them with the Transportation Master Plan, and increase density outside the downtown core to match the proposed density inside the core.  There would be a more uniform and less suburban feel to all of Ann Arbor.  The commercial and manufacturing districts are the focus of this rezoning, although some residential areas are also being directly affected by the AHP proposed changes.  Of more significance, however, is the fact that the City has residential neighborhoods that abut these commercial/manufacturing/research zoned districts.  The proposed setback and density changes will affect the adjacent neighborhoods in some very real ways.

The basic premise is that new non-residential development outside the downtown core should also be pedestrian centered, walkable and focused on an urban look.  The buildings should be pulled forward on the lot, with parking behind or underneath.  If this means the building becomes taller, that’s acceptable.  Large parking lots that separate people from where they would shop are not acceptable.  At the same time, the City wants new buildings to reduce the amount of impervious surface and improve mass transit access points.

So – the Area (how much of the lot is being used for the building) becomes smaller.  The Height becomes taller.  And the Placement becomes closer to the street, pulled away from the neighborhoods (if possible) with parking underground or behind buildings, less visible.  The focus is on mass transit and pedestrian/bike use instead of car dependence.  See also New Urbanism.

Area Master Plans

The City has engaged in a series of master planning efforts to create visions for the future of Ann Arbor.  Citizens’ committees have spend years (literally) working to develop these visions.  However, these visions have frequently been more reflective of the current situation than visions of the future.  They have been inevitably become dated, as a result.  These plans provide some guidance to the City staff as they try to work with developers and neighborhoods, but after a few years, they need to be revised.  After 10 years, they have become hopelessly outdated; after 15 years, they are rarely relevant.

In addition, these plans are not implemented in the sense of rezoning the area.  New developments may follow the area plans – or not.  The area master plans are merely advisory, according to the City Attorney, and lately people who dedicated long hours, months and years have felt that time was wasted.

The City is currently trying to revised and conform all the area master plans to update them.  However, this won’t make it any easier to implement them.

The Area Master Plans and their adoption dates are:  The Downtown Plan (1988) [encompasses the DDA boundaries excluding South University], The Central Area Plan (1992) [encompasses the DDA boundaries plus surrounding areas], The South Area Plan (1995), the West Area Plan (1995), the North East Area Plan (2006)

Boulder, Colorado

The Mayor, several members of Council, several members of the DDA, and members of the Downtown Citizen Advisory Council took a side trip to Boulder a few years ago on their way to the International Downtown Association Conference.  Boulder is similarly sized, home to the University of Colorado, has a greenbelt, and had a very different take on development incentives.  The Council members were inspired to return to Ann Arbor and make some changes in how Ann Arbor confronted downtown development.  (Here’s a link to the Boulder government pages:  Out of this visit grew the Calthorpe Process and A2D2. 

“By-Right” development

This term – which is poorly used and poorly applied by all who use it – literally means that zoning regulations allow certain types of development.  If a development fits within the appropriate zoning (it’s residential in a residentially-zoned area), has setbacks, height, number of units – in other words, Area, Height and Placement in keeping with the zoning – then people call it a “by-right” project.

Properly, a development that fits the zoning is only that – one that complies with the zoning. 

The Calthorpe Process

Several years ago the City hired Peter Calthorpe to help with a ‘visioning’ process to define the future of downtown Ann Arbor.  Here’s a link to Mr. Calthorpe’s biography:  Calthorpe works in Berkeley, CA.

Mr. Calthorpe led a series of public workshops to help Ann Arbor determine the future shape of downtown.  He and his team met with civic/governmental leaders and citizens, looked at the results of those meetings and the workshops, and then presented their report.  The report is available on the City’s website: 

Those who attended the workshops (like me) were struck by the set of assumptions we were given at the beginning of the exercise at the first workshop:  Here are your maps of Ann Arbor’s downtown.  Here are a series of cutout shapes representing various kinds of buildings, including residential, civic, service (like grocery, dry cleaners and pharmacy).  Here are other cutouts to represent parks and open space.  You have several premises to work with:  Slow growth over the next 10 years, moderate growth, or significant growth.  If you want services, you must allow for significant growth.  Growth of as many as 5000 new residents would be required (as I recall) to support the services of a grocery, pharmacy, hardware store, dry cleaners, etc.  Show us your vision for Ann Arbor in 10 years.  You have 30 minutes.  We were told that ‘no growth’ was not an option.

The first meeting held a mix of long-time residents of Ann Arbor and urban planning students.  Subsequent meetings were dominated by urban planning students, as the long-time residents became disillusioned by the sense that the outcome was pre-determined.  One of the recommendations was that the City should establish the A2D2 committees.

DDA – Downtown Development Authority

The Downtown Development Authority comes into play because it’s a quasi-governmental organization that uses tax dollars and other income and because it’s geographic area determined the study area for the A2D2 rezoning.

The DDA uses tax dollars from new development to build and improve the infrastructure in downtown (resurfacing streets, repairing sidewalks, and similar projects).  The DDA also uses dollars to encourage the development of specific types of projects.  (For instance, the DDA has accumulated a significant amount of money to use for affordable housing projects, when it finds a suitable way to use these funds.)  In addition, the DDA is able to bring in funds through parking revenue that it can turn around and use in capital projects such as in building and rebuilding parking structures.   These parking dollars also generate revenue that the DDA provides to the City’s general fund.


We throw this term around a lot, with many different meanings.  This is the way I look at it:

When you stack people on top of each other, you increase density.  When each person has less land around them, you increase density.  Small lots equal higher density.  Bigger buildings equal higher density.

What are the advantages of high-density developments?  Ann Arbor limited its horizontal growth, so we cannot expand outward.  And all over our country (not just locally) household size is decreasing.  There was a time when people lived in average households that were 4+ people.  That’s an average, which means that many were larger and many were smaller.  Now the average household size in Ann Arbor is 2.15 (for more on this see  Planners and builders look at that average size and think – more units, smaller units, push them closer together, there’s a market there! 

FAR – Floor Area Ratio

The Floor Area Ratio helps to define density for developments.  The lot size is considered the Floor Area.  So, a one-story building that covered the entire lot would have an FAR of 1.  A two-story building that covered exactly 50% of a lot would also have an FAR of 1.  If it covered ¼ of the lot and was four stories tall, it would also have an FAR of 1.

Because most buildings won’t cover all of their lots, their FARs will be figured out using math that I’m not prepared to explain (utility closets don’t count; elevator shafts don’t count).  In the new zoning under A2D2, the general D1 zoning will have an FAR of 4.  Premiums can then be added to this base FAR that will allow a building to be taller, but not exceed a certain height limit –depending upon location.

New Urbanism

If you didn’t study Urban Planning in the last decade, or you haven’t been to a lot planning meetings, this term still needs some explanation. 

Were you a child in a small town in the 50s?  Were you a child in the city?  If you could answer ‘yes’ to either of those questions, you actually already understand New Urbanism.

New Urbanism has a couple of tenets:  1.  Walking, biking, and mass transit are better ways to get around than using a car.  So all the services we use should be located close enough that we can walk, bike or use mass transit to get to those services and get back home again conveniently.  In turn, we should make using alternative transportation attractive and safe enough that people will use it to get to various services rather than use their cars.  2.  People like to live in villages, whether vertical or horizontal.  Mid-20th century planning removed that piece of information from the equation, putting all the housing over here, and all the services over there.  Getting from where you live to where you want to be became very difficult.  New Urbanism looks at creating / reinventing co-located housing and services. 

New Urbanism is responsible for the increase in mixed-use developments (residential/office/commercial) being proposed and built, the emphasis on alternative transportation in the transportation plan, and the fresh look at where buildings are placed in the Area, Height and Placement study.

Planned Unit Development (PUD)

This term is used to describe a special rezoning for a development that doesn’t fit the existing zoning of the land for which the development is proposed.  Originally, a PUD was intended to allow a developer to propose an innovative design that stretched the boundaries of the existing zoning definitions.  More recently, through a series of changes initiated by Council, the PUD process has become more of a check-sheet.  Is there affordable housing? Check.  Is there a green component? Check.  Is it LEED certified?  Check.  And so on.  Each check allows the developer to build higher/denser.  There are no rewards, however, for innovative design.

A PUD needs Council approval, as does any rezoning, and can be turned down by Council.  Once turned down, either at the Planning Commission or Council stage, the PUD proposal is not dead.  It can be redesigned and resubmitted as long and as often as the developer chooses.  Once approved, the proposed PUD does not need to be built.  It can be renewed administratively or by Council once every 3 years (or more often, if there’s a revised site plan).

Setbacks, Roof Heights and other confusions

Side, rear and front setbacks determine the placement of any development.  This becomes the maximum area a building can have on that lot.  Each type of zoning has its own setbacks.  In a residential neighborhood, this might be a 15 foot side setback – so there has to be 15 feet between your house and your property line.  However, in my residential neighborhood (zoned R2A) there’s only a 5 foot setback required.  That means, my house could be only 10 feet from my neighbor’s houses, if each of us built maximum size. 

Roofs are not defined in the City’s zoning standards.  Who knew?  However, the maximum height of buildings is defined, and therein lays the rub.  If a building with a flat roof is 30 feet tall, that entire top story is useable.  However, if a building with a peaked roof is 30 feet tall, much of that top story is NOT useable.  The City doesn’t want buildings in residential neighborhoods built with flat roofs.  So, how can they encourage peaked roofs?  By defining the proper height as the midway point in the roof – but that leads to confusion and allows for very tall roofs that create more problems.

Irregular lots cause other problems.  When a develop unites several lots to create one large lot in order to maximize building potential and FAR, often the lots have different dimensions and differing rear lot lines.  This creates an irregular lot.  The City has to determine what the buildable area is and where the setbacks are.  For instance, the City will select the first part of the lot where a 20 foot line can be drawn parallel to and 10 feet away from a back lot line, and will determine that this is the back lot line.  This might allow the developer to design a building that is 5 feet from the lot line in another part of the lot, however.


Initially, this term was applied to growth outside Ann Arbor – the increasing development of large houses on large lots in the townships.  People moved to these developments, not just from Ann Arbor, because they were close to Ann Arbor and were able to enjoy Ann Arbor’s amenities, but could have larger houses on more land while paying lower taxes.

More recently, sprawl has been used to describe residential neighborhoods within Ann Arbor that are larger houses on larger lots and far from work and shopping areas.  These neighborhoods are transportation-dependent and generally perfect for commuters.  However, they aren’t great for walking down to the corner store and picking up a quart of milk – there is no corner store.

Traffic and Transportation

Before any large development is approved (I’m not certain about all developments, but certainly any development that involves parking and curb cuts) the City requires the developer conduct to a traffic impact study.  This study can be quite extensive, and may involve several streets and signals.

Mass transit (the bus system) can also play a role in development, as a developer may work with AATA to guarantee that the bus system will provide service to a proposed development, if it is approved.  The developer may work with City traffic engineers to determine the best way for bus service to work, whether there should be a bus pull-off built into the street, whether the street needs to be widened, whether there should be bus shelters, whether there should be new stop signs or signals, or any other considerations that could arise out of increased traffic as a result of the proposed development.

These proposals become part of the presentation to the Planning Commission and the City Council.

Traffic increases are not themselves reasons to reject a project, as the City Council recognizes that street improvements, signaling and other changes can be made to accommodate the increase in traffic.  Traffic and pedestrian safety are considerations, however, in the overall presentation of the developer’s awareness of Ann Arbor’s needs and expectations.