Urban Neighborhood Small Block Four House Cluster Plan - Concord
At the request of a local developer, Concord city staff requested Arnold Mammarella demonstrate a design for pedestrian oriented urban blocks with moderate density single-family homes or town homes. The prototype block would need to be able to be repeated as part of neighborhood street grid and have homes with architectural facades fronting pedestrian paths and collector streets as well as urban thoroughfares. Houses facing thoroughfares also needed to address security and sound attenuation for private outdoor spaces, while fronting the street.
The response was a schematic plan for a 4-house cluster on a small block. A pedestrian pathway was placed on one edge of the block so that two 4-unit clusters could be combined to make a larger block. Ideas from pedestrian friendly, traditional urban neighborhoods, and courtyard housing typologies guided the design of the design process. The 4-unit concept block is 90 feet by 180 feet curb-to-curb (i.e., including space for wide sidewalks, planting buffers, and street side planting strips). Each of the four lots is 36’ x 77’ or 2,772 SF and the homes are arranged courtyard style around a partially sunken parking court accessing each home’s two car garages. Two of the homes (House A) are fully detached but use a zero-lot line setback on one side, while the other two homes (House B) are attached along the garage side at the shared lot line. This allows each home to be treated and sold like a detached single-family residence even though the lot lines are not perceptible on the plan or to a passerby. It also is efficient in that valuable land is not wasted on small, unused side yards. Courtyard terraces are also used rather than lawn areas, because of their efficiency in achieving usable outdoor spaces on small lots. These outdoor spaces a buffered by raised landscape planters and building walls to make them quiet, comfortable and visually appealing. The homes have gated entries for security, but the entries are close to the building line, so the property does not have an alienating walled off or fenced off look.
The homes are diagrammatically Spanish Eclectic in layout and massing given the climatic fit with the hot arid Concord summer but could be adapted to other styles fairly easily. House A at 2,125 SF has 4 bedrooms and 2.5 baths with a split-level design that features the dining room overlooking a large, high ceiling living room and a large kitchen with separate glass bay nook adjacent to a terrace as well as a large courtyard off the living room. House B at 2,050 SF has 4 bedrooms and 3 baths. It also features a split-level design with a large, high ceiling living room and 3 separate courtyards. Both homes also have an entry court and entry foyer so that the front door does not open directly into the living room, as is often the case with homes this size.
The layered, spatially rich approach to the cluster house and block plan addresses neighborhood design concerns yet allows for modestly sized homes that feel much bigger and grander. They also achieve a fairly high residential floor area of about .75 relative to net site area and a net density of 16 units per acre, which would translate to 10-12 units per acre gross density for a neighborhood (i.e., density including neighborhood streets, sidewalks, and other amenities).
One of the outcomes of the study is that it shows that a small block concept combined with the cluster arrangement is a viable strategy for moderate density housing with single-family housing qualities such as attached garages, private entries and private yards and courts. The layout is applicable to moderate to large size urban infill lots or new suburban neighborhoods where a more traditional neighborhood character is desired.
