With both city leaders and members of Congress discussing alterations to DC’s height limit, I think there are a few things worth highlighting.  These are just some thoughts on what I think are the core issues here, and how DC might proceed.

Why do this?  The compelling reason must be economic, and the reasoning behind this change will need to be carefully communicated to the public at large.  A limitation like this involves a number of trade-offs, and must be understood just as the costs of other zoning restrictions need to be understood.

There ought to be a campaign that both illustrates the benefits of density, but also the costs of restricting development – both in terms of opportunity costs of limiting agglomeration economies, but also of the general costs that raise rents and prices for all sorts of real estate in the region. (see many previous posts from Ryan Avent – 1, 2, 3, 4, 5, among many others)

At the same time, changing the height limit won’t be a panacea.  The real estate market in DC is regional, other local governments will need to pull their weight as well.

Reverse the question: why shouldn’t we do this?  Taking a page from the concept of shifting the procedural burden of land use regulation, perhaps the question needs to be flipped on height limit proponents – if not up, where will the city grow?  Will commercial areas encroach into residential ones?  What about the costs of pushing development further out into the region?  What about the costs of rising rents?

The height limit is not zoning.  It’s worth remembering that most of the District is regulated to maximum densities well below the maximum envelope of the height limit.  Likewise, these areas represent some of the best opportunities for cost-effective, small scale infill development: the “missing middle” of housing densities.

 It is important not to get too caught up in the density numbers when thinking about these types. Due to the small footprint of the building types and the fact that they are usually mixed with a variety of building types, even on an individual block, the perceived density is usually quite lower–they do not look like dense buildings.

There are many opportunities for this kind of infill development in DC, whether on alley lots or via the conversion of English Basements and other additions of multiple units into otherwise single-family zones.  Smaller scale multi-unit buildings can also be designed as to be visually indistinguishable from neighboring single-family homes.  This kind of development ought to be allowed across the board (and DC is moving in this direction), an example of incremental changes to the regulatory environment.

That said, those kinds of developments won’t impact the height limit.  In DC’s largely residential areas, I doubt a taller limit would have much effect.  Conversely, raising the height limit without increasing the allowed density brings little economic benefit.

“Vistas” and “views” are overrated.  Atrios said it.  Most of the ‘views’ people talk about when discussing DC’s tourist-caliber photo shots are enhanced by tall buildings, not the other way around.  The buildings frame the views down street corridors.   Most of the people are not viewing things from the stereotypical aerial shot, but rather from street level.

Instead, what people seem to be concerned about is about the city’s skyline becoming a vista in and of itself, distracting from monuments and memorials.   I don’t think this is of concern, as skylines can be manipulated just as easily as other physical elements of the city.  Likewise, any alteration of DC’s height limit is not likely to suddenly trigger a free-for-all of skyscraper construction, but rather a slow climb to a new, higher equilibrium.  The overall impression from afar would still be that of a ‘flat’ skyline, the monuments and memorials would get their respect while the rest of the city would have room to grow.

The “Monumental Core” and “Downtown” are not synonyms.   The reported initial conversations on height involve minor changes in the already-tall areas, and transit-oriented height districts elsewhere. Matt Yglesias:

 They seem to be contemplating two different ideas, either or both of which could be implemented. One is to tinker at the margins with the restrictions on downtown structures to allow an additional floor or two of leasable office space. The other is to allow for substantially taller buildings in a few outlying areas, with the thinking being that if we can have tall buildings right across the Potomac in Arlington County there’s no reason peripheral parts of D.C. shouldn’t have them too.

The idea of protecting the monumental core from the intrusion of tall buildings is a worthy urban design cause, but also largely a strawman.   The NCPC’s Monumental Core Framework Plan is discussing this area in blue, while the broader ‘downtown’ is represented in brown/tan, showing the area of DC’s Center City Action Agenda.

 While adding some buffer around the White House, the larger point is that downtown already has most of the city’s tall buildings.  Furthermore, if we’re talking about adding a modest increase in heights allowed in DC (something along the lines of allowing buildings to be twice as tall as the streets they front on, rather than the current limit of street width + 20 feet), then views like this and this within the monumental core will look exactly the same in all of the tourist photos.

Always remember – the reason to do this is to add density, and perceptions of density (such as equating it with height) are often inaccurate.

There will be a plan. Lydia DePillis wisely notes that any change would need a plan, and not just open the door to willy-nilly skyscraper development.  In the event that this comes to pass, I’d expect both a detailed map and accompanying restrictions to protect the vistas we do have, as well as a strong urban design component.   Potential options could be altering the existing formula (what if the limit were 2x of street width?  Or street width + 75 feet instead of 20?) and could easily introduce mandatory setbacks at certain heights to avoid urban canyon effects (think along the lines of a less-tall version of New York’s 1916 zoning code building envelope).

Such a plan could also identify areas for truly tall buildings, DC’s own version of La Defense or Canary Wharf.  Doing so should be part of a conscious urban design, rather than the isolation of the Tour Montparnasse.

Added density provides opportunities to finance new infrastructure.  What better way to link transportation and land use than to fund new transportation infrastructure via tax revenues from new development?