DC and accessory dwelling units

Capitol Hill.

I have been interested in this for a long time, have written a lot about it, and believe that a targeted support program could create a many thousands of units in neighborhoods where back lots are deep (ours is 90 feet long), ideally targeting areas within one half mile of a Metrorail station.

-- Plus1 House, California ADU resource center
-- ADU Design Guide, Santa Cruz California
-- ADU units design guide, Tacoma, Washington
-- Building an ADU, Salt Lake City
-- ADU resource page (including guides), AARP

Neighborhoods like Capitol Hill and Georgetown are known for both "English basements" and carriage houses, which often are rented out.

DC has changed the rules to make it somewhat easier, but there are still various constraints. But it's not cheap.  It would cost at least $150,000 to $250,000 to construct, plus permitting etc.  It turns out that having "free land" doesn't make construction of such a dwelling unit much cheaper.

Image by architect Ileana Schinder from profile in Dwell Magazine.

An article ("Enduring less ado with an ADU") last week in the Washington Post shocked me though, because an ADU in the 16th Street Heights neighborhood (somewhat more than one mile away from our house, but nowhere near a Metrorail station) is renting for $1,975/month.

From the article:

They also incorporated a rehabilitation loan for $150,000 to cover the cost of converting the two-car garage into a 500-square-foot, one-bedroom rental unit. The couple imagined a hip space in the alley, but having to stay within the limitations of the existing garage put a stop to that idea. ...

Free-standing ADUs are subject to the same building codes and zoning regulations as a full-sized house. Conversely, they do not have their own address and are not deeded separately. They cannot be bought, sold or gambled away. ...

Before the project was complete Fazio ran ads on Craigslist and Reddit using Schinder’s renderings to showcase the space. “We had a dozen people interested in the first week,” Fazio says. The selected tenant is now in place and paying $1,975 a month. Fazio says the rent is “as high as anybody is paying for a one-bedroom in this neighborhood.”

That level of rent--albeit not priced as "affordable housing"--makes putting in such a unit financially efficacious.

But on the Columbia Heights e-list, one correspondent derided ADUs as anything but affordable.  My response was:

"if you have to get a loan to build the unit, the add on to the mortgage payment will be at least $1,000 and the construction cost will be financed privately."

If you want to offer these as lower cost rental units, they'd have to be subsidized by at least half the cost.

Potentially convertible garages to the rear of the 4400 block of River Road NW in Greater Friendship Heights.

Then again, it could well be worth it, as the production of one unit of housing would be 25% or less compared to the cost of traditional construction of a single unit of affordable housing.  OTOH, such a unit wouldn't be permanently affordable.

Parking still required.  One hindrance is that you can't convert a garage without replacing the otherwise foregone parking.  That requirement should be reconsidered, especially within one-half mile catchment areas of transit stations, at least in typical detached housing zoning districts.  In rowhouse districts it should vary, maybe, but definitely shouldn't be required in areas close to transit stations.

That's why in the photo above, there's a parking pad next to the building.  Although other photos in the article show that they repurpose the space more frequently as a patio.