How to Design Affordable Small-Lot Housing in Urban Areas
- Nov 12, 2010
Small-lot infill housing has become more ubiquitous in urban areas such as New York City as developers seek to cash in on trendy older neighborhoods. Architect Carmi Bee describes his development and application of contemporary prototypes for such housing.
By Carmi Bee, RTK&B Architects
In the realm of housing the prototype is an age old idea, and there are many prototypical dwellings in recorded history, including the African hut, the North American tepee and the Middle Eastern tent.
The advent of the industrial age meant that an ideal housing model could be produced in multiples along the lines of other manufactured goods, leading to efficiencies with commensurate cost savings. This can be seen in numerous freestanding residential examples including Frank Lloyd Wright’s Usonian house, Buckminster Fuller’s Dymaxion house, Levittown houses, and Sears Roebuck prefab houses, to name a few. On the other hand, urban models include the English and American row house, the tenement, and Le Coŕbusier’s Unité d’habitation.
Present day “Smart Housing” follows in the tradition of these urban models with one key difference: It was also conceived as a strategy to restore older neighborhoods by enabling scattered open sites, where existing buildings were demolished, to be replenished with new efficient, low-cost housing. This strategy to bring about the regeneration of urban communities incrementally was based on the theories set forth by seminal thinkers such as Jane Jacobs.
My own interest in designing affordable housing began while I was a student at The Cooper Union in the late 1960’s. Urban renewal at that time was a major governmental policy that promoted large-scale land clearance. For my undergraduate thesis I developed an “anti-urban renewal” plan for a large portion of Manhattan’s East Village. Instead of creating large wastelands, my plan was based on an incremental rebuilding of the community. The infill prototype I developed was a 100’ x 100’ modular unit based on courtyard housing. This meant that a typical New York City block measuring 200’ x 400’ would have eight units that could be developed individually.
In the late 1990’s, this prototype strategy underwent another transformation, aimed at filling vacant lots scattered throughout the city’s residential neighborhoods. This step in the design’s evolution came about from collaboration between myself and Michael Lappin, president of the Community Preservation Corporation (CPC), a not-for-profit lending company that specializes in financing affordable housing in the New York and New Jersey region. I approached Lappin to discuss strategies for delivering affordable housing to the outer boroughs of New York. John West, who at the time was the senior vice president of Community Preservation Corporation Resources (CPCR), a for-profit subsidiary of CPC, worked with me on its development. What emerged was the “Smart Housing” model which would represent the latest development in the evolution of affordable housing for New York City.
As a team we analyzed the street grid and found that the majority of blocks were broken up into 20-25 foot modules. Therefore, one objective of our research was to determine a range of building widths that, in combination, could accommodate a typical range of lot sizes.
The prototypes were designed to work within the R-6 districts which would yield 50-110 dwelling per acre. The New York Department of City Planning defines R-6 as a moderate-density residential district that falls “…into two categories: non-contextual and contextual. Non-contextual districts (R6, R7, R8, and R9), sometimes called height factor districts, are generally mapped where there is a mixture of building types and no predominant context. Contextual districts are those districts with an A, B or X letter suffix (R6A, R6B, R7A, R7B, R7X, R8A, R8B, R8X, R9A, R9X, R10A and R10X). Contextual districts, where development must comply with the regulations of the Quality Housing Program, are designed to maintain the scale and form of the city’s traditional moderate and higher density neighborhoods. These districts are mapped where buildings of similar size and shape form a strong neighborhood context or where development would create a uniform context (Residence Districts).”
The Quality Housing Program was created in 1984 in order to preserve the established character of a number of residential neighborhoods. It sets forth height restrictions, but allows for greater lot coverage in order to achieve a maximum Floor Area Ratio (FAR), the formula used to calculate maximum allowable floor area in a building. The required number of parking spaces for these types of developments is also reduced because there is less open space.
The infill housing prototype is a four-story walk-up building with eight units that fits within the context and scale of the typical R-6 neighborhood. There are five versions of the prototype, which are designed to accommodate typical New York City infill lots widths (25’, 31’, 35’, 42’) and a typical 30’ x 70’ corner lot (Figure 1). There are also four wedge-shaped plans (+7⁰, +15⁰, +30⁰, -30⁰) that fit odd-shaped sites (Figure 2). Two or more different versions can be grouped together to fill several adjacent lots to form a large housing complex with multiples of eight units, but each eight-unit building functions and is articulated as an individual building with its own entrance and staircase. Open space and parking may be shared among the entire complex.
Although the prototype plan can vary from site to site, the building section remains basically the same and is the keystone of the prototype (Figure 3). It takes advantage of the constraints in the building code, lending affordability to the project. The building section has four stories, a cellar, a mezzanine level in some cases, and a single staircase serving all the units. Each unit is accessed from the stair landings, eliminating the need for a corridor and keeping the circulation space compact. A second means of egress is not required by the NYC Building Code which states that a building that is not more than 60 feet high with a maximum gross area of 2,000 square feet per floor can be served by a single egress stair where the horizontal travel distance is not more than 50 feet per floor. In a recent change to the building code it has been increased to 2,500 square feet.
As a cost savings strategy, recent projects have a slab on grade with a partial cellar that houses technical equipment and utilities. The two first-story units are always ADA accessible.
These units also have the benefit of access to the rear yard. The second-and third-story units are typical in plan. In some models the fourth-story unit is a duplex apartment with a typical first floor plan and a mezzanine with an additional bedroom and bathroom housed under a sloped roof. The typical unit plan has a living room, a bathroom, a gallery kitchen, a small dining area and a laundry closet. The number of bedrooms per unit is dependent on the width of the lot. For example, the 35-foot model has a one-bedroom unit and a two-bedroom unit per floor. One duplex has two bedrooms, while the other has three. Both the 42-foot wide building and the 30’ x 70’ corner building can accommodate two-bedroom flats throughout with three-bedroom duplexes. The bedroom on the second floor of the duplex unit overlooks the living room on the first floor. It has operable windows or skylights for fresh air and natural light.
In addition, the circulation and dining areas vary with the lot width. In the 31-foot wide model, for example the entrance of each unit leads to a corridor from which all rooms can be accessed. There is no designated dining area, but it is assumed that the occupant can place a small dining table in the living room. In the 35- and 42-foot wide buildings, the space within the unit that would otherwise be a corridor is wide enough to accommodate a small dining area. The units in the 30’ x 70’ corner building have a kitchen that is open to a large living room/dining room, creating a single open, fluid space.
An energy saving feature of the prototype plan is the double-exposure layout, which ensures that the living room and bedrooms receive fresh air and daylight. Having windows at opposite ends facilitates cross ventilation, keeping cooling costs low in warm weather. LEED-certification is planned in future projects, attainable with a few modifications in the selection of materials and finishes.
The single-stair idea was first tested at 384 Atlantic Avenue in Brooklyn. The four-story plus penthouse infill building, designed by RKT&B architects and developed by CPCR, has retail space on the ground floor with eight one-bedroom units on the upper floors. Unlike the prototype models, it fills a 50’ x 100’ lot. However, it was designed as a walk-up with a single staircase with “crossover” balconies, to allow crossing between apartments in case of fire. When opened in 2002 the Atlantic Avenue apartments were rented at market rate: six of the one-bedroom apartments rented for $1,500 per month, while the other two one-bedroom apartments, which have decks, rented for $1,750 per month. The duplex units rented for $2,400 and $2,500 per month. Profits made from market-rate projects go back into CPC/CPCR to finance affordable housing.
From the Atlantic Avenue project, the team learned that the walk-up building with a single stair without an elevator proved to be very cost-effective. In addition, the sloped roof meant that roof access was not required as per the building code, so the stair did not need to continue to the roof.
The first prototype, Prospect Gardens, was built at 249-251 16th Street in Brooklyn’s Park Slope neighborhood. It is located in an R-6B contextual zoning district. The site is made up of three adjacent 25’ lots which were combined to create two 37’-6” lots. The Prospect Gardens plan most closely resembles the 35-foot prototype model, with three one-bedroom and three two-bedroom flats, a two-bedroom duplex and a three-bedroom duplex per building. However, the extra 2’-6” per lot allows each room to have more generous dimensions. The rear yard can be accessed only from two first-floor American with Disabilities Act (ADA)-accessible units.
The building department allowed the required parking to be waived. Under typical circumstances, one parking space per dwelling unit would have been required for this type of development within an R-6 zoning district. This would have resulted in the creation of 16 parking spaces (8 per building). However, a provision reduces the parking requirement to cover only 50 percent of the total number of dwelling units on zoning lots of less than 10,000 square feet. This reduced the total parking to 8 spaces (4 per building). An additional provision sets forth a “waiver of requirements for small number of spaces.” Up to five required spaces may be waived on an R-6 zoning lot. Thus, Prospect Gardens’ total required parking was waived by the building department.
The single, glass-enclosed staircase that ties the entire project together is celebrated on the front façade of both buildings. We did something that Europeans have been doing for a long time: moving the stair to the outside façade, so that walking up the stairs becomes a more acceptable and interesting experience. The stair becomes an extension of the street, evoking Jane Jacob’s “eyes on the street” social surveillance method. Conversely, there are eyes on the stairs from outside giving tenants a heightened sense of security inside the building. At night the stair becomes a lantern, illuminating the street below.
There were several cost cutting methods employed in Prospect Gardens. The stair was a crucial money-saving device. As mentioned before, the single stair eliminated the need for an
elevator, and a second means of egress was not required because of the construction classification and restricted floor area. Also, the sloped roof eliminated the need for an additional flight of stairs up to the roof. This alone was responsible for cutting about 20 percent of the would-be cost of the building had it been built with an elevator and a stair. Careful material selection also helped keep costs low, for example, the interior walls of the stair and painted concrete block. Savings on labor came through hiring local builders who could easily handle the small-scale project. Remarkably, Prospect Gardens was built for only about $100 per square foot in 2004!
While Prospect Gardens was being built, the Park Slope neighborhood underwent a demographic change that drove real estate prices up. As a result CPCR decided to sell the units as market-rate condominiums. The final sale price was $425 per square foot, a figure somewhat below the actual market rate. Since then, 16th Street has sprouted a fresh crop of luxury condo buildings that have filled vacant lots dispersed throughout the block.
Following the success of Prospect Gardens, 1451 Dean Street in Crown Heights has been completed; 1007 Putnam Avenue in Bedford-Stuyvesant has started construction; and the Our Lady of Loreto site in Brownsville will start construction in the Fall of 2010. Each project will have 48 affordable units. Curtis + Ginsberg Architects, a New York City firm, has taken the prototype and applied it to a project at 45 Malta Street, as has Michael Avramides for a site on Watkins Street. CPCR wanted to see what would happen to this work if it were given to different architects. Concurrent with the development of the “Smart Housing,” the American Institute of Architects’ New York City chapter’s Housing Task Force published 10 Steps to Create More Affordable Housing in New York City. This document sought to amend sections of the building code dealing with multifamily dwellings in order to promote higher-density, low-rise affordable housing.
Carmi Bee, FAIA, is principal at the New York-based RTK&B Architects.