What does a house look like?

Find a little kid and ask them to draw a house. Go ahead, I’ll wait.

Finished? Alright, chances are, your kid’s drawing looks something like this:


Single-family, detached house with a pitched roof and a chimney in the middle of a yard with no neighbors in sight.

This makes sense in a lot of places; for a lot of American kids, that’s probably the only type of house they’ve ever lived in. The funny thing is, I think this image is so archetypal that even kids who live in a city like Philadelphia, where there are almost no houses that look like this, would draw something like this if asked to draw a house. So I wanted to look and see; in America’s biggest cities, what does a standard house look like?

I made a list of America’s 50 largest cities, and looked up information on housing units from the American Community Survey (ACS) conducted by the US Census Bureau. The ACS classifies housing types into ten groups, based on the number of housing units in the building: 1, detached (single-family detached homes); 1, attached (rowhouses, townhouses, and twins); 2 (duplexes); 3 to 4, 5 to 9, 10 to 19 (small apartment or condo buildings); 20 to 49, 50 or more (large apartment or condo buildings); mobile homes; and other (boat, RV, van down by the river, etc.). I included the national numbers for comparison. The results are below, and a spreadsheet with the information can be found here.

House Type Graph

Of the top 50 cities in America, 39 had a lower percentage of single-family detached housing than the nation as a whole; however, detached housing is still the predominant form of housing in all but six of the cities, and made up more than half of all housing units in 27 cities. Of the six cities where detached housing was not the primary form, there were three types.

In New York, Miami, and Washington, DC, the primary housing type is large apartment buildings such as towers. In New York this building type is very dominant, whereas in Miami it is only about 4% higher than detached housing, and in DC it is less than 1% more common than rowhouses.

Philadelphia and Baltimore are the only cities in America where rowhouses are the predominant housing type. In both of these cities, they make up more than 50% of housing units. Philadelphia has the lowest percentage of detached housing on the list, at just over 8%.

And all on its own, Boston’s predominant housing type is 3-4 unit apartment buildings. These come mostly in the form of the New England triple-decker, a three-story apartment building with one unit per floor.


The other thing I notice looking at the results is that it shows the lack of small-scale multi-family housing, also known as “missing middle” housing. This housing type is important for providing affordable housing without some of the negative consequences of the highest density forms of housing. They also provide a smoother transition between detached and high-rise forms of development, and allow the density that is necessary for mixed-use development.

So is the first image what a “house” looks like? Well, for a lot of people, yes, but not for everyone. For some people it looks like a rowhouse, or a garden apartment building, or a condo tower. But it’s important for cities to have a better mix of these types, so that there is room for anyone regardless of what sort of house they call home.

Can cities be too dense? Can condos be too tall? Are they built to last? : TreeHugger

Condos under development in Toronto. From treehugger.com.

In this post, Lloyd Alter, one of my favorites, weighs the pros and cons of density, as demonstrated by the residential housing boom in downtown Toronto. Although Alter does point out some of the benefits of density, he seems to be in the “too-dense” camp. I’d like to address some of his concerns.

Can cities be too dense?

Alter mentions the various advocates of density and critics of zoning ordinances that say allowing the market to determine the appropriate density would allow for more affordable housing and economic development. He then cites two sources that mention how added density increases demand on services, as subways and sidewalks become crowded.

This would definitely be the case, if a municipality were to provide the same level of services despite increased density. But a municipality should be getting higher tax income due to more property taxes, and at higher densities, economies of scale become a factor, where it becomes cheaper to provide municipal services. They can afford to make transit more frequent, have more cars, or extend lines. If sidewalks are crowded, it creates an opportunity to form a pedestrian only district. The situation where this sort of density exists in North America is very rare, and districts would of necessity be very small, but they should be on the table. These are perfect issues to be addressed through impact fees. If a developer is still going to make millions by building a tall condo tower, they are more willing to give a few thousand in fees to improve transit or green space. In short, I think the only way cities can become too dense is if the public services and amenities we expect in the city fail to keep pace.

Can condos be too tall?

While admitting to some of the efficiencies that large buildings provide, Alter argues that towers should not be “so high that it gets depersonalized and anonymous because there are just too many people packed in slab towers.” I think that this moves out of the realm of urban design and into architecture, where an architect can create a building that minimizes the impacts of a tower on its street or block. I think that it is also important to incorporate cafes or at least proper lobbies into towers. My building does not have a lobby and there isn’t a cafe within a few blocks, and as such I don’t know many of my neighbors very well, but I have friends who live in buildings where people do homework, meet people, and even eat in the lobbies of their building, and it goes a long way toward creating a community.

Are they built to last?

Again, Alter’s argument against towers is more architectural than urban design related. He cites a source that discusses how towers are leaky and hard to retrofit, which means they will be rented, and as property values decline, these will become “where your grandchildren are going to come to buy crack.” This coincides closely with the views of James Howard Kunstler on the topic. Alter also mentions that these buildings are terribly inefficient energy wise, since they often have small operable windows, if at all, and their glass facades generate a greenhouse effect. These are all strong points, and I would add that towers also run the risk of outliving the fashionableness of their architecture. But again, I feel like these issues are related to architectural designs. Buildings can be built that have operable windows, use greywater systems or allow for proper cross ventilation. It’s not that condos are bad; it’s that we allow bad condos to be built. If there is anything cities can do, it is demand a higher standard of design from their developers.

Computer Modelling Could Help Boost Urban Wind Power – CleanTechnica

How can we maximize the usefulness of wind power in the city? From cleantechnica.com.

Joshua Hill reports on the efforts of a research team at Murdoch University in Western Australia. Their work involves creating a 3D model of wind flows. This is important because the existing 2-d models don’t do a good job of indicating how hills, trees, and buildings effect wind flow, especially in the third dimension (for instance, how useful is the updraft on the front of a glass tower for wind power?). Their model is already showing that wind turbines in urban areas face greater stress than previously thought. This study could map out conditions that would create maximum efficiency for small-scale wind power.

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