This week, I attended a presentation put on by Jeremy Drucker of 49 Mile, the architect/developer behind Sacramento's 9 on F project. He came to talk about a potential future series of projects based on expanded use of Sacramento's alley lots.
When downtown Sacramento was originally split into parcels, several standard lot sizes emerged. A downtown Sacramento block is 320 feet by 340 feet, split into two halves by an alley 20 feet wide. Each subsequent 320x160 block is split into eight 40x80 foot lots (about 1/13 of an acre) along the numbered streets and four 40x160 foot lots (about 1/7 of an acre) along the lettered streets.
Drucker's idea is to build alley-facing units in the back third of the 40x160 lots. Now, for anyone familiar with midtown alleys, this is nothing new. Many property owners built "granny flats" on the alley facing of their lots. Sometimes these units were built in place of a garage in back of the unit, or built above a garage, while others were built in place of a garage or parking spaces. Building these flats had many benefits: it provided a source of extra income for the property owner, or allowed residents with large families to have a little more elbow room. Generally, an alley apartment is inexpensive, which helps maintain the central city's affordability. As zoning laws changed and the central city emptied out in the mid-20th century, the practice of building alley apartments generally faded out.
One point I tend to repeat again and again is that most "new urbanist" ideas are simply the way that we used to build cities a century ago, and alley units, as we see, are no exception. However, Drucker wants to add a few twists to the concept that make the idea a positive one in many areas, including urban infill, energy conservation, affordable ownership, and historic preservation.
Currently, there is an interest in urban infill in the central city, placing new projects on vacant lots. However, the number of these lots is limited. Exploring the use of alley lots could potentially mean hundreds of new units, integrated into existing neighborhoods. Drucker's current 9onF project provides a model for what these units might look like. The concept drawing I saw featured a three-story design, with a garage for four vehicles facing the alley on the ground floor. An ADA-accessible ground floor unit takes up the front half of the ground floor unit. Two more units occupy the second and third floor, both of which have patio areas atop the garage, facing out towards the alley. Each unit would have one parking space, and the fourth parking space would belong to the house that occupied the front portion of the lot.
Unlike the historic role of alley units as rental housing, these would be for-sale units. Because of their small space footprint and alley frontage, they would potentially be affordable to buyers that would otherwise not be able to afford central city housing. The other economic advantage of alley units is that the owner of the original 40x160 lot would make a nice chunk of change selling the back 60 feet of their lot: potentially, about $100,000!
This brings me to the portion of this idea dearest to my own interests. One of the problems with all of the attention on midtown development is that owners of central city homes face great pressure as land values rise. Some developers engage in lot consolidation, buying several adjacent lots with the intent of demolishing the buildings. When demolition permits are too hard to secure via normal channels because the buildings are historic, occupied and/or intact, many buildings fall victim to "demolition by neglect": buildings are allowed to remain vacant, decay and fall into disrepair until either the city can be persuaded to allow demolition or an "accidental" fire simply eliminates the house.
Alley development reduces this economic pressure by making lot consolidation and demolition less appealing. It allows a great increase in overall density in the central city: potentially, five total units could be placed on a 40x160 lot (about 36 DUA.) So a lot with a single-family home could add 4 units in the back, a duplex could add 3 units, and so on--a lot with an existing fourplex could even add a fifth single-unit "granny flat" in the back. But all this density could be achieved without demolishing a single existing structure. And because of the economic benefit for the owner of the property, projects like restoration of existing properties becomes much more economically feasible: an extra $100K goes a long way to restoring a faded Queen Anne or Craftsman bungalow to its original grandeur, money that would otherwise have to come from other sources. It makes historic homes a lot easier to preserve, and reduces reasons to knock them down.
It's a "triple win" from a development perspective: it increases density and walkability (and thus urbanity), it makes home ownership in the central city affordable to more people, and it promotes preservation of existing historic neighborhoods.