Common mistakes of form-based codes


New Urban News

Issue Date:

Tue, 2008-04-01

Page Number:



Daniel Parolek, Karen Parolek, and Paul Crawford have identified nine errors that people commonly make when designing and applying form-based codes (FBCs). “These mistakes often can invalidate the quality of an FBC and its intent very quickly,” they warn in Form-Based Codes, published by Wiley.

“Even one of these mistakes can threaten the predictability of the form and character of new development, and reduce public confidence in the code, as well as its effectiveness,” the authors write. The nine mistakes are:

Confusing, overly detailed, or insufficiently detailed land-use tables. A code’s tables should be distilled down to a single page (or slightly more) for each zone, while ensuring the compatibility of adjacent uses. A table “should not attempt to list every possible use,” the authors advise. “It is helpful to use a performance-criteria approach to land uses, such as the hours that a business can operate, the size of a business, and whether the business has a drive-through.”

Using density to regulate development. If you try to make density a primary tool for regulating built form, the results will probably not turn out as expected. This is because a particular density can be achieved by buildings that vary widely in height and character.

To educate local elected officials and planning staff on the benefits of regulating physical form, and not density, the authors suggest taking walking tours of neighborhoods and housing types that exceed what the community regards as acceptable density — but that are well-designed and would in fact be appropriate. Southern California’s courtyard housing complexes, for example, often have 40 units per acre, yet most people like them — and are surprised to learn their density.

Not calibrating parking to the Transect. “Restrictive parking requirements have been one of the biggest obstacles for high-quality infill and greenfield development,” the authors say. “For example, retail and commercial uses at mixed-use neighborhood centers located within walkable neighborhoods should not have the same high off-street parking requirement as the same uses in a suburban strip-mall context.” If people fear that a large store may come to a neighborhood center and require more parking, deter the threat by using performance-criteria-based regulations, such as a limit on store size.

Not calibrating open-space requirements to the Transect. Good infill and redevelopment projects can be obstructed when suburban open-space requirements are applied to urban settings. If the code for a downtown insists upon a certain square footage of shared open space for each project, this may eliminate projects on small lots — and encourage lot aggregation and larger buildings, possibly inconsistent with the community’s character.

Building placement. Standards for building placement are sometimes not specific enough or sufficiently predictable from the perspective of the community or a developer. “There should be some wiggle room within these regulations, but not so much that the built result is not predictable or that the intent is not clear. … a developer should know that if a submitted project adheres to all the regulated criteria, then the project will get approval.”

Using a lot-coverage percentage. If lot-coverage percentage regulations are used at all — which the authors argue against — “they must be based on a thorough documentation of an area and must be calibrated by Transect zone. … Including noncalibrated percentages in your FBC can automatically prevent the revitalization of existing neighborhoods, as well as the creation of new neighborhoods with a character similar to those of the old ones.”

Using floor-area ratio. FAR should have no role in form-based codes. “If FAR is used as a primary tool for regulation and entitlement, a developer will simply max out the FAR, thus creating very ‘boxy’ buildings with little variation in massing. … An appropriate combination of height, maximum building depth, distance between buildings, and size and massing requirements within Building Type Standards should be used instead.”

Not addressing frontages. “Documentation of typical frontages and their application to the FBC regulating system should be considered an integral component because they regulate an appropriate interface between the public and private realms within a community. Hire a consultant who knows what frontages are.”

Not using administrative review. “The intent of going through the FBC process, including the visioning process, is to establish community and political support for a specific vision that the FBC then regulates for predictable results,” Crawford and the Paroleks say. “Therefore, once the vision is established and the FBC is written, projects that meet FBC requirements should be approved administratively.” This gives developers an incentive to meet the code’s requirements.

If special-interest groups are accustomed to participating in project review, and consequently oppose the elimination of discretionary review, the authors say “the solution is to engage these groups in the FBC process early and often.” The goal is to “ensure that the team has their full support for the vision plan and full confidence in the FBC.”