The cottage, which won a top design award last year from the American Institute of Architects, is technically called an “accessory dwelling unit,” or A.D.U. Portland has been ahead of the curve in allowing these smaller housing units, which are illegal in many cities and towns under current zoning rules…
In 2010, during the economic slump, when many building plans were being shelved, Portland presciently began to allow homeowners the right to develop accessory dwelling units on standard 5,000-square-foot residential lots for the first time. The city also eliminated development charges of up to $15,000 for new accessory dwelling units to spur homeowners to build.
More incentives followed: Homeowners could build and even rent out a unit that did not have off-street parking; any design not visible from the street could be built without input from neighbors; and new height limits — raised to 20 feet from 18 feet — encouraged two-story units, like Ms. Wilson’s…
Not surprisingly, the concentration of accessory dwelling units has been in central, higher-income areas close to amenities like transit and shops. “Part of this could be due to the fact that people with large amounts of equity can more easily secure financing,” Mr. Wood said. “The City of Portland and Portland State University will be working on a project to encourage and facilitate A.D.U. development in more diverse neighborhoods.”
It may be helpful to compare the ADUs to other alternatives for affordable, small housing.
- Would residents and communities prefer tiny houses on their own lots or in communities of tiny houses? The first could be expensive due to the cost of land, defeating the purpose of the smaller housing which is supposed to be cheaper. The second could be too much of a change for some places. ADUs make use of existing lots and aren’t necessarily grouped together.
- Would residents and communities prefer larger apartment buildings? On the plus side, you can build more units up and everyone knows that this is an apartment structure (with its higher densities and other unique features). On the negative side, apartment buildings can alter the character of a neighborhood, may require parking, and people often have stereotypes about who lives in apartments. The ADUs hide the higher densities better than apartments – back behind the main housing unit – but don’t provide as many units.
Given the resistance of many municipalities to denser housing, I imagine ADUs could be attractive as they don’t require the density or size of some alternatives. Additionally they can use existing land and generate income for local residents. Even given all that, I think it would take a lot for many cities to adopt this. There is a large need for affordable housing throughout the United States and many communities don’t seem to be moved to do anything; I’m not sure ADUs are attractive enough to tilt the scales.