Form-Based Codes Institute at Smart Growth America

Buildings & Blocks

Fundamentals of Fenestration

Fundamentals of Fenestration

How much of a building exterior is covered with openings, in particular windows and doors, how transparent the enclosing glass is, and how the openings are arranged are issues of fenestration. Not all form-based codes concern themselves with building fenestration. FBCs commonly regulate street width, block size, and buildings’ disposition on their lots and orientation to sidewalks—all issues affecting walkability. One can debate whether fenestration is also about walkability. It’s clearly more interesting to walk past buildings with windows and doors than ones without.

Fenestration Sidewalk

Fenestration on building facades is key to making public spaces social.

Just as important, fenestration influences the social character of public spaces. Fenestration affects how welcoming the building is and whether it participates with other buildings in creating a visually harmonized and immersive landscape. A neighborhood plan—a view from above showing the layout of streets, blocks, and building rooftops—leaves out this important thing that a form-based code can provide—what is the quantity and quality of the fenestration on buildings.

“A city is an ecological balance of things Public and things Private.
Fenestration is the portal between the two.”
– Geoff Ferrell

One of the most common arguments for windows from an urban design standpoint are that they provide eyes on the street and inhibit street crime—the important view is from inside to outside. But windows with reflective one-way glass can provide that. Views from outside to inside are also important. As eyes on a face are windows into the state of a person, windows as transparently glazed openings humanize a building by intimating the internal life of the structure. Compare this to tinted glass curtain walls or horizontal ribbon windows where it is hard to have any confidence that there are even rooms behind the glass. When the wall plane of a building is visually impenetrable and doesn’t appear to have openings, it affects not only the welcoming feel of the building, but also the social feel of the public spaces it faces.

Fenestration Comparison

On the buildings at the left, windows contribute a positive social tone. The visually impenetrable buildings on the right convey indifference to the public spaces they face.

The streets of Paris benefit from the unwritten fenestration standards of Baron Haussmann, the engineering prefect of Paris who oversaw the city’s redevelopment in the 19th century. He advocated a window aspect ratio and spacing that can be seen on most facades for the entire lengths of many of Paris’ iconic streets. The effect is to create urban spaces visually tied together throughout. His design dictums had the enforcement weight of Emperor Napoléon III behind them. In our time it is difficult to get a Parisian degree of design conformity from building to building. Nevertheless, some degree of pattern consistency from building to building harmonizes place identity.

Fenestration Paris

The example of Paris demonstrates the influence of fenestration standards on the experience of urban spaces. Parisian street walls are harmonized by consistent sizes and spacing of windows from building to building.

A fenestration element in a form-based code typically describes the required amount of window and door area as a percentage of the wall—for example 30 to 90 percent of a commercial ground floor facade, and 20 to 70 percent of the upper story facade. This range may vary depending on the urban context. When calculating the opening area of a door or window, many form-based coders exclude non-transparent parts such as lintels, frames, sills, and mullions, but include window parts such as muntins if they are less than an inch wide. Historically fenestration didn’t take up a large percentage of walls. In the example facade below, the upper fenestration comprises 19% and the lower fenestration 26% of their respective wall areas.

Fenestration Diagram

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Market-Responsive Form-Based Codes

Market-Responsive Form-Based Codes

Originally published in Better! Cities & Towns, April-May 2013.

Richardson, Texas, an affluent inner-ring suburb of Dallas, and home to many telecommunications corporations, wants to remain attractive to employers in coming decades.

Key to that goal is becoming more walkable and connected to transit, qualities that many of today’s young and talented professionals are seeking. There are five Dallas Area Rapid Transit (DART) stations in Richardson, and unfortunately not one is in a walkable neighborhood. Such areas are in short supply in Richardson, which grew up entirely after World War II.

But a 100-acre previously undeveloped parcel adjacent to one of the stations will establish a new pattern: The site was rezoned recently for 3,200 residential units and up to 6,000 jobs. State Farm Insurance Company, which could have located anywhere in the region but was looking for a walkable urban center, chose this site.

As long as builders adhere to a new form-based code (FBC), no further public hearings are required. “We eliminated the risk of NIMBYism for a theoretical maximum buildout within a wide range of uses,” says Scott Polikov of Vialta Group, LLC, A Gateway Planning Company. “There’s nothing more market-responsive than that.”

A February report by real estate consultant Robert Charles Lesser & Co. (RCLCo), called “Market Pitfalls of Form-Based or Smart Codes,” criticized some FBCs for market inflexibility. Although the report cited no specific codes — and so was difficult to refute —it stung some new urban practitioners who take market demand seriously.

Bush Central

Bush Central TOD plan. Plan courtesy of Vialta Group, LLC, A Gateway Planning Company

Developers who wanted to reduce political and business risk initiated the code for the Bush Central TOD, as the Richardson site is called. The city gained assurances that the public realm would be built out in a way that is walkable and mixed-use, while the developers got flexibility and “by-right” entitlements, Polikov says. The master developersBush/75 Partners sold all the land, at a premium, within a year and vertical construction is underway at a rapid pace. Zale Corson Group is developing an urban multifamily project designed by JHP Architects, and KDC Development Company has purchased the remaining land for a mixed use, live-work-play project.

“We made the argument that this kind of development is required to keep attracting corporate citizens,” he says. “They wouldn’t be able to bring in the cool, echo-boomer development without a form-based code.”

City entitlements allowed higher densities without micromanaging uses, he adds. Within the 18 urban blocks that make up the site, uses are mostly flexible. On some streets, buildings must have first floors that accommodate retail — but other uses can occupy these areas if the market for retail lags.

“The form-based code allowed us to get a richer building envelope and enabled development to evolve over time,” Polikov says. “That’s a big story that the RCLCo criticism misses.”

The Bush Central TOD — named after a nearby highway that is named after the first President Bush — is laid out on a simple grid to be built out intensely. Public spaces are plentiful and a large natural park with trails along a creek will provide a connection to nature. The project will create a regionally significant urban center for the north side of Dallas.

Trinity Lakes

Across the metro area on the East Side of Fort Worth — a far less affluent part of the region — a form-based code was approved in December 2012 for a 175-acre transit-oriented development called Trinity Lakes.

This project is in the middle of suburban sprawl with a diverse Latino/white/African-American population. An existing commuter rail line between Dallas and Fort Worth borders the site, but a station needs to be built. A high-speed thoroughfare, Trinity Boulevard, bisects the site and must be transformed into a complete street.

Trinity Blvd Proposed

Trinity Boulevard in East Fort Worth is currently a highway but will serve as a town center. Rendering courtesy of Vialta Group, LLC, A Gateway Planning Company

The city, having adopted a FBC for an area adjacent to downtown, has experience with this type of regulation. The Trinity Lakes FBC was the first proposed by a private developer in Fort Worth. Residents of a large adjacent development, who have nothing but commercial strip retail nearby, were all for it. “They are sick of driving out of East Fort Worth for amenities that other neighborhoods have,” Polikov says.

Fort Worth is an area that gets a lot of development: In 2013, more than 4,000 residential building permits were issued in the city, about a third of them for multifamily units. But nothing like this has been attempted outside of the downtown core, let alone in a working-class neighborhood.

The city agreed to tax-increment financing (TIF) for $75 million in infrastructure to build the rail station, convert the highway into a multiuse boulevard, and pay for street, stormwater, and other improvements. The city and county will get a portion of new taxes for 20 years and then 100 percent thereafter.

The site links into the Trinity River Trail system in addition to the regional rail network.

The FBC is similar to the Richardson project. As long as the form-based aspects are adhered to, the developer has by-right entitlement to build out the project. “Form-based coding provided the vocabulary to communicate the benefits to neighbors, and it was the analytical vehicle to estimate a much higher tax-base capture,” Polikov says. Planned development in Trinity Lakes is estimated at $750 million, and it could transform this part of East Fort Worth.

High desert Savannah

Affluent or working class, the Dallas-Fort Worth metro area is a fast-growing region with 6.5 million people, and what works there may not work in other parts of the US. Clovis, New Mexico, with a population of 37,000 and located 90 miles from Lubbock, Texas, the nearest city of any size, could not be more different. Yet a market-based FBC could work there as well, Polikov says.

Cannon Air Force Base, a big part of the town’s economy, is expanding with a special operations command headquarters. Many officers and enlisted personnel have lived in Europe or big cities. A 640-acre project by local developers Jeff Watson and Sid Strebeck is designed to create the kind of environment that would appeal to the service men and women.

The project takes up an entire square mile section north of town, and the first neighborhood will be anchored by a middle school and park for which the developers are donating the land.

Saddlewood Plan Map

Saddlewood in Clovis, New Mexico, takes inspiration from Savannah, Georgia. Plan courtesy of Vialta Group, LLC, A Gateway Planning Company

Saddlewood is designed around 20 squares, much like Savannah, Georgia, and each square will be a module for development that includes a full range of housing types. The housing surrounding each square is, in effect, a phase of development that allows market flexibility, Polikov says. “We looked at historical places that allow variety but replication and we were influenced by Savannah,” he says. “There’s a predictable amount of infrastructure investment and we can build as much as we need,” he says.

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