As I discussed last time, CodeNEXT introduces a new concept, “building types.” If you are developing a property within a transect zone, you must select a specific building type from the palette allowed in that zone – a “wide house” or a “duplex: side-by-side,” for example, in the T3NE zone, or a “rowhouse: medium,” “multi-plex: medium,” or “multi-plex: large” in the T5N.SS zone.
Anyone who works with the code must know which type can go where, as must anyone who cares about the distribution of housing in the city (or in their own neighborhood). But there are 19 building types and 13 transect zones (not counting open sub-zones). It is daunting to keep track of what goes where.
I posted this table of building types by transect zone right after CodeNEXT was released:
This is a useful reference sheet, but it highlights the code’s complexity rather than simplifies it.
We can start by recognizing that many of the 19 building types are simply variations of a single base type:
- There are four flavors of detached single-family houses: the “long” house, the “wide” house, the “small” house and the “cottage” house. These differ only by their required minimum lot widths and by their maximum building footprints (which the code somewhat confusingly calls “building envelopes”). A “cottage” house is limited to 1½ stories; all of the others may be two stories. Two other building types – the “cottage court” and “cottage corner” – just involve a specific arrangement of the cottage house type around a common green space. Altogether, there are six types of detached, single-family houses.
- There are three types of duplexes: the duplex: front-and-back, the duplex: stacked, and the duplex: side-by-side.
- A multi-plex is a small apartment building that looks like a single-family house. There are two types: the “large” multi-plex, which, sensibly, is classified as a “large house” form, and the “medium” multi-plex, which is classified as a “medium house” form.
- There are two types of rowhouses: “rowhouse: medium” and “rowhouse: large.” The difference lies in the “run” of units. A medium rowhouse consists of a short run of rowhouses and is classified as a “large house” form. A large rowhouse consists of a longer run of rowhouses and occupies most of a block.
- There are a few one-ofs: “live/work,” “main street,” “courtyard building,” “low-rise,” “mid-rise” and “high-rise.” Most of these types are self-explanatory. “Live/work” units are, essentially, rowhouses with residential above ground-floor services or retail uses. “Main street” buildings units are one- to three-story buildings with retail or service uses on the ground floor and upper floor service or residential uses. "Courtyard buildings” are u-shaped buildings organized around a courtyard that is open to the street.
We can simplify things further by distinguishing between the main street zones and the neighborhood zones. The “main street” and “live/work” building types are reserved for the main street zones. The main street type will be the workhorse of the T4MS zone and (along with the mid-rise) the T5MS zone as well, but it is not permitted in any of the neighborhood interior zones. Conversely, few of the building types allowed in the neighborhood zones, such as multi-plexes or courtyard buildings, are allowed in the main street zones. The main street zones and the neighborhood interior zones are coded to be fundamentally different kinds of places, particularly considering the broad mix of commercial and retail uses allowed by right in the MS zones. When comparing transect zones, we should compare neighborhood zones to each other and the main street zones to each other.
Here is a chart that I hope simplifies the complexity of building types and transect zone. The first chart compares the base building types allowed within the interior neighborhood zones. The second chart compares the two main street zones. (I am ignoring T6 high-rise zones for now.)
This chart helps us spot an important hole in the transect zones. The T3 zones allow a variety of single-family and duplex building types. The T5 zones allow a variety of four- to six-story buildings, including almost all of the “missing middle” types of housing like rowhouses, multi-plexes, courtyard buildings and low-rise apartments. T4 should provide a transition zone from T3 to T5. T4 should provide, in particular, a space for the 2-3 story “missing middle” types of housing we’ve heard so much about these past few years. But the T4 zone is reserved strictly for two-story buildings and, worse, is missing most of the middle building types. Consequently, the T4 zone is really just a “single-family plus” zone.
There are clearly some housing types tailored for T4 that inexplicably have been relegated to high-density zones. Medium rowhouses, for example, are classified as merely a “large house” building form but they are shunted to T5 zones that allow much larger buildings.
Or take the courtyard building, which is a u-shaped building arranged around a street-facing courtyard. The courtyard must comply with detailed regulations dictating the dimensions of the courtyard and its relationship to the surrounding apartment units. The whole point of these detailed regulations is to break up the mass of the building as perceived from the street. A properly designed, three-story courtyard building should occupy a niche in the medium-density T4 zone. But courtyard buildings are relegated to the highest density T5U zone, where they must compete with 75’ mid-rise apartment buildings. Will anyone even take the trouble of build a courtyard building rather than a less-regulated low-rise or mid-rise building?
T4 ultimately offers no real transition from T3 to T5 because it does not provide a place for the low-rise, 2-3 story missing middle.
It is a bust.
As this chart shows, we will not allow much diversity of building type in the main street zones. The T5 main street zone will allow large 5-6 story VMU-style buildings; the T4 main street zone will be limited to 2-3 story buildings, but not much else This lack of diversity will force us to get the MS zones just right on the map. Very few corridors can sustain a solid wall of commercial buildings for more than a few blocks. Let's hope we guess right.
The consultants are supposed to release their own summary charts this week, which I'm sure will be more comprehensive and elegant than mine. But my charts have the virtue of existing today. Hopefully, whatever the consultants release will make it easier for people to have rationale discussions about what the code does well and what it does poorly.