A Town Well Planned: Universal Form Codes

This article is part of a series in which Strong Towns member and contributor Alexander Dukes proposes a “Civic Development System” for designing strong neighborhoods. The system's regulations are split into three core mechanisms — Master Street Plans, Land Use Zoning, and Form Plans — and intended to provide maximum flexibility for developers in a way that fosters economically successful communities. We hope Alexander's ideas serve as valuable inspiration when thinking about design options for your own neighborhood.

Read previous articles in this series:

  1. Introduction to a Town Well Planned
  2. Determining Public Will 
  3. Parcels and Master Street Plans  
  4. Street Design 
  5. Hierarchical Zoning 
  6. Zoning with Context

Form codes and plans are relatively new regulatory tools in the civic planning toolbox intended to better control the design of developed land. In regulating the form of land, planners primarily seek to control building heights, footprints, frontage, and setbacks. Note that form codes and form plans are not the same thing. A form code defines the terms by which the design of land will be regulated, such as: “the city’s building height limits will be divided into three 30, 50, and 70 foot increments.” A form plan applies that form code to specific blocks or parcels, such as: “the city will apply 30 foot height limits along Oak Street, and 50 foot height limits along Spring Street.”

In this article, a foundational form code and form plan will be developed for this series’ case study: the Auburn Mall site. These codes and plans will be universally applicable to all parcels in the site. In the next article, we’ll dig a little deeper into form plans and use some geographic context to apply more specific regulations on individual parcels.

As a refresher, let’s take a look at the types of lots that are available to developers in the Auburn Mall site as it’s been platted and zoned:


As shown, the majority of parcels have dimensions of 25 x 50 feet, 25 x 100 feet, or 50 x 100 feet.  This means that space on most parcels is at a premium. Any form code that regulates land use on parcels this small must balance reasonable safety and appearance regulations against landowners’ desires to maximize the use of their land.

The General Form Code and Parcel Plans

On the mall site, all parcels will be governed by the form code described below:

Auburn Mall Site Form Code (Part 1)

Lot Front – Defined by the city, this lot edge requires built structures to present the public face of the parcel. Generally, the front of a lot is the side that meets the street/sidewalk. Within illustrations, the front of a lot is indicated with a black arrow.

Port and Starboard – Refer to the left (port) and right (starboard) sides of a parcel, as oriented from the front of the parcel. In the maritime context, the “port” side of a vessel is the left side of the ship when looking to the front of the vessel. The “starboard” side is the right side when looking to the front.

Primary Structures – Structures that have 3 or more of the following 4 characteristics: (1) Being essentially enclosed with impermeable walls, (2) climate controlled with active cooling/heating of air, (3) serviced by water/sewer utilities, and (4) only accessible through lockable exterior entryways. Primary structures are typically homes, offices and other buildings that people occupy.

Porches and Other Auxiliary Structures – Generally, structures that have 2 or less of the following 4 characteristics: (1) Being essentially enclosed with impermeable walls, (2) climate controlled with active cooling/heating of air, (3) serviced by water/sewer utilities, and (4) only accessible through lockable exterior entryways. Auxiliary structures tend to be garages, sheds, and other structures that aren't meant for human habitation.

Structural forms that constitute exceptions to the general rule will be maintained by the city. 

Except for lots with industrial land uses, porches are the only auxiliary structures permitted on the front edge of a lot unless a particular auxiliary structure has been specifically permitted as an exception by the city.

Front and Rear Build-to Line, Build Areas – The area(s) or line(s) a primary or auxiliary (one or both of which will be indicated) structure must be within or abut. Exceptions will be made for garages and other auxiliary structures specifically described.

If no build-to line exists, the front lot line itself functions as the “build to” line for auxiliary or primary structures. If no build area exists, the entire parcel may be built upon — excluding setbacks, minimum build depths, and maximum build depths.

Setbacks ­– Setbacks define a distance from a given lot edge or other geographic feature within which construction is either restricted or not allowed at all. Ex: “We cannot build a home within the 5 foot setback from the port-side lot edge.”

Minimum Build Depth – The distance from a given lot edge or other geographic feature within which construction of a defined description must occur. Ex: “The minimum front porch depth from the lot’s front edge is 5 feet.”

Maximum Build Depth – The distance from a given lot edge or other geographic feature within which construction of a defined description may occur. Ex: “The maximum front porch depth from the lot’s front edge is 10 feet.”

Generally, parcels will be governed by applying the aforementioned form code to the parcel form plan illustrated below.

Regardless of the parcel’s size, the dimensions in the General Parcel Form Plan will be applied to almost every parcel in the development (except for parcels zoned R1, which we’ll get to momentarily). The structure footprints shown in yellow, green, and brown are examples of what developers can do within the regulations. I’ve also included the street designs developed in the series’ fourth article for context.

If one thinks back to the first article in this series, this illustration represents the mating of two of the three elements the A Town Well Planned series: Parcel/Street Plans and Form Codes. A developer would only need to look up the Zoning Plan to gain most of the regulatory information about their parcel. Splitting development regulations into three simple elements is vastly more streamlined compared to most municipalities’ planning processes.

These spatial allowances in the General Parcel Form Plan provide developers the maximum utilization of the limited square footage they are afforded. As shown, the optional “auxiliary setback zone” gives developers the option of adding porches and other outdoor seating areas on up to 50 feet of lot depth from the front. This is in addition to the 6 feet of “pedestrian flex space” allocated in the street design for public solicitation. (See Street Design article in this series for more information on pedestrian flex space and other street uses.) With the adaptability provided by these regulations, commercial land uses can optimize this combined 56 feet to create inviting outdoor dining areas or open air markets, offices can feature breezy porches where their employees relax or work in the fresh air, and avid gardeners can have greenhouses attached to their homes.

On the rear, parcels have another 20 feet of space provided for auxiliary structures that don’t belong on the street-facing front of the lot (such as sheds and garages), plus an additional 4 feet of public right of way on the rear alley dedicated to “owner authorized utility.” This utility space on the alley can be put to use in any non-structural way that the abutting property owners see fit — for instance, using it as a place to store trash cans. Finally, primary structures must be setback at least an additional 4 feet from the parcel’s rear edge. The 4 foot setback and the 4 foot utility lane exist to keep activities like trash pickup, parcel delivery, and car parking out of the alleyway’s “woonerf” style shared pedestrian/auto lane.

Detached Home Parcel Plans

The aforementioned general form dimensions will apply to all land uses except the “R1” residential zone for the lowest intensity residential neighborhoods. (See Hierarchical Zoning article for further explanation of these zones.) The R1 zone allows up to 8 people to live on a parcel with a minimum of 200 square feet per person. Generally, such parcels will be used to host single family homes and duplexes (though one could conceivably place 8 individual tiny homes or micro-apartments on a parcel). Because single family and duplex land uses tend to be more vulnerable to hazards like robbery and fire, parcels zoned “R1” will feature form dimensions that attempt to mitigate these risks. The dimensions for parcels zoned R1 are illustrated below.


In the R1 Form Plan we can immediately see that the side setbacks and shorter front porch allowance are the main differences between the R1 Parcel Plan and the General Parcel Plan. Additionally, there is no mention of a rear porch or auxiliary space on this plan, which means the amount of rear auxiliary space is left to the discretion of the lot owner. Finally, there is also a front porch minimum depth, which means a front porch is required for R1 land uses.

The “minimum side setback” is 1.5 feet wide on the starboard sides of parcels and 3.5 feet wide on the port sides. The reason for these setbacks is to force structures on each lot to have a minimum of 5 feet of distance between structures while still providing sufficient room for someone to walk along the port side. The purpose of forcing 5 feet of distance between each structure is related to the International Building Code, which stipulates that buildings with less than 5 feet of distance between them and the nearest lot line must have a fire wall rated to last one hour. This design fudges this a bit, and enforces a five foot separation between each building.  If the fire chief has a problem with it, the homes will just have to be built out of brick.

Porches of at least five feet in depth are required at the front of the lot, with a maximum of ten feet of porch depth allowed. The purpose of requiring porches on these lots is to discourage unauthorized trespass or peering onto the lot. These porches are intended to act as southern incarnations of the “stoops” featured on brownstones that are popular in northeastern cities like Brooklyn and Philadelphia. Adding a few steps to elevate the doors and windows of the living space above the street contributes to the privacy of the residence while still maintaining that safety that comes from “eyes on the street.” Such measures are employed to provide residents with a sense of security and “defensible space” in a relatively dense environment.

Little Big House

Now, many people who are used to large suburban lots may consider a 25 x 100 foot lot far too small to build a reasonable house upon. While this may have been true in comparison to homes built in the early 20th century — when sturdier building materials like steel and glulam were rarely used in single family residential construction — homes on small lots today can be far roomier and open than those built a century ago. To demonstrate this point, I have designed a three bedroom, three bathroom home that can fit on the smallest lot in the mall site design: 25 x 50 feet.

Please note: I’m not an architect. Though I did as much research as I possibly could on common regulations governing the dimensions required within residential plans, it is likely that I missed something. Nevertheless, I am relatively confident that the necessary changes would be minor and that the basic layout of the house is acceptable. Below is a plan view of a two-story, three bed, three bath home on a 25 x 50 foot lot.

This home design is the intellectual property of Alexander Dukes. It is used here with permission.

This home design is the intellectual property of Alexander Dukes. It is used here with permission.

Is the home a bit snug and cozy? Yes. On a 25 x 50 lot, a home designed to sleep four to six people is going to have compressed living quarters compared to a suburban estate. On the other hand, consider the amount of money a decent-sized family can save by building this house on such a small piece of land. If the first floor office and guest bedroom are leveraged as kids’ bedrooms, a family of six can live in this house relatively comfortably. Alternatively, a family of four can invite an aging grandparent to live in the home with them. I even left space for a car to park!

Keep in mind, this is the smallest lot in the whole mall site design. Residents on more common 25 x 100 lots can construct homes larger than this and still have room for a small backyard and two car garage (as shown on the R1 Parcel Form Plan).

Finally, the following sketch demonstrates how this single family residence would appear on the street with all of the R1 regulations applied.

I think that’s a perfectly reasonable southern home within a tight-knit downtown community. And by applying both the general form dimensions and the special R1 dimensions to the whole mall site plan, we end up with a vision for a beautiful southern community in Auburn.

The next and final article for this ‘season’ of the series will demonstrate additional form plan elements that need to be applied with geographic context to the site and show how everything we’ve discussed thus far will come together to establish a framework for a successful, intimate urban environment.

(All graphics by Alexander Dukes)

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