What I found interesting to note is not only the frequency of accessory houses, but the presence of four lots (in the center of the image at right, although there are several others in the town) of typical Seaside dimensions of 50'x100' which have each been subdivided into two 50'x50' lots, a size very close to that which Nathan Lewis has suggested for a dense neighborhood of single-family detached homes. The only access to these lots, as with the accessory houses, is by the lanes. Despite the small size of the lots, the houses are quite ample:
A city of residential lots of this average size, using a distance between houses the same as that in the lower photo (about 16') for rights-of-way, and with short and narrow blocks of 300'x100', would attain a density of over 9,100 units/square mile, or, using the American average of 2.59 persons per household, around 24,000 people per square mile. A few wider streets would be needed at intervals, but they should not alter this outcome greatly. A real life example is Nathan Lewis' own Tokyo suburb of Seijo, which he's used to familiarize us with the neglected area of Japanese urbanism:
The Seijo street view, with a remarkably Seaside-like house on the left:
Or, at right, consider an entire neighborhood built along these lines. This is a development at the fringes of Tokyo -- just a bit further west steep mountains quickly rise up. It also happens to be about 70 acres, very close to Seaside's 80. Even the street network is vaguely similar, yet density is about 25% higher. It's not necessarily a model to be copied, but it does show what could be accomplished using the basic 50'x50' lot that Seaside pioneered along with 16' streets. To densify further, while retaining a single-family detached form, subtract half or so of the 50'x50' lots and replace them with the "accessory dwellings" that are abundant at Seaside, and which, under separate ownership, can fit on their own 20'x25' lots:
These cottages offer around 500-800 square feet, not much different from the "micro homes" currently being built in Portland that commenter Vince has mentioned.
The promise offered by these common sense innovations at Seaside unfortunately has not carried over into most New Urbanist developments. At Kentlands, for instance, although many individual houses can fit within a 50'x50' lot, a rear yard of equal size has typically been reserved for a detached garage, an issue I've talked about before. But the lessons of Seaside are there for anyone willing to look a little closer at the remarkable planning that went into it.
For more on these issues, I strongly recommend reading Nathan Lewis' site if you haven't discovered it already:
- How To Make a Pile of Dough with the Traditional City 5: The New New Suburbanism
- How To Make A Pile of Dough With the Traditional City 4: More SFDR/SFAR Solutions
- How to Make a Pile of Dough with the Traditional City 3: Single Family Detached in the Traditional City Style
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| Yours truly enjoying a beverage and a good book in Seaside after a day exploring the town. |
Interesting. In the town where I work as a planner, we have an old neighbourhood just south of downtown that was laid out in the early 20th century that has quite wide streets rights-of-way (50') with 20' back lanes - paved street widths are 23' and 13' respectively. Most of the lots in the area are a uniform 50x110 and over the past 10 years many of the corner lots have been subdivided into 50x55 lots (2750 sq. ft) and have worked quite well.
ReplyDeleteBecause the 20' lanes are not seen as legitimate streets in the eyes of the Town's planning regime, we do not permit the mid-block lots to be subdivided into two 50x55 lots, and instead recent zoning changes have permitted the mid-block lots to be subdivided into 25x110 lots so that each lot maintains its own "street" frontage. (Including the 4' side setbacks, that leaves 17' of buildable width.) Although this zoning change is already 2 years old, no one has yet to build one of these narrow houses, and instead we get constant inquiries about subdividing the 50x110 mid-block lots in half so that one lot would front on to the lane.
Our (planning dept) response has traditionally been "a lane is not a street. all subdivisions must have street frontage. no can do." However this is a total construct of the planning dept's mind, because (a) this requirement isn't written down anywhere, and (b) legislation requires lots to have public right-of-way access, and doesn't differentiate between different types of ROWs.
Since I started working there I have been advocating to allow the 50x55 mid-block subdivisions, as there is clearly less desire to do the "skinny" lots - builders seem to prefer the square lots, even if they front on a "lane". It's funny that the discussion essentially ends up being one of "what is a street?" rather than a discussion about the viability of the land uses. I believe that the lanes would actually become the more desired properties, given the human-scaled street and reduced vehicle speeds and volumes. Much like the Japanese model of street that NathanNWE identifies.
Seaside may be a good model to show my colleagues that this is possible in a NA context - thanks for posting!
Hi Corey -- thanks for the comment! Very interesting perspective. I agree, and think that a real estate analysis would almost certainly show that a 50'x55' lot is more valuable, all else being equal, than a 25'x110' lot, in large part because the dimensions are more practical (for instance, you get a larger house for the same perimeter if it is square-ish rather than elongated). Given that lower levels of traffic and traffic speed are also associated with higher residential desirability, I'll bet your intuition about the value of properties along a narrower street is exactly right.
DeleteI've written about this peculiar attitude toward the so-called "rear alley" in North American urbanist thought (the same sentiment prevails in both Canada and the United States), under which the alley is considered to not have any independent identity apart from the wider street that it is paired with. This is reflected in the categorization of dwellings fronting on this alley as "accessory dwellings" rather than individual addresses in their own right. The New Urbanism has perpetuated this thinking, but Seaside, arguably the first NU project, did not follow this same logic. It is an unusual case, though, in that the alleys are actually pedestrian paths rather than intended for automobile access.