In DC, it’s not uncommon for people to build onto the top of their houses when they want more space. Another way to expand— one that gets less attention— is building behind an existing home. But a recent zoning change makes it harder for homeowners to do that by making it illegal to extend a house more than ten feet beyond its neighbor's back wall.
There are a lot of upsides to rear addition development. It allows an owner to expand an existing small footprint of an older home back into a yard, but you can rarely see it from the street, meaning it (in theory, of course) doesn’t raise the same concerns about unsightliness that pop-ups sometimes do. Building in back yards adds value to a property, has the potential to create dwelling units for a city starved of them, and is a semi-private way to develop.
There is a valid criticism, however, that additions can block light from neighboring properties. So like all kinds of residential developments in the District, rear additions must meet a few zoning requirements:
Lot coverage (a percentage of the lot covered by the house)
Rear yard setback requirement (a required minimum depth of open space from the rear lot line of the property to the house)
Additions on the back of existing homes can extended into the back yard until the lot coverage is maximized or the rear setback is met. Depending on the size of the lot and the size of the existing house, the addition maximum could extend from just a few feet to twenty or more beyond the rear wall.
The rear addition, however, will soon be under more scrutiny. On March 27th, the Zoning Commission agreed to amend the Zoning Ordinance to include a third qualifier to limit development in the back yard: a ten-foot maximum build-out from the furthest adjoining property’s rear wall. The rule will go into effect at the end of April.
Now, a homeowner’s rear addition can’t extend more than ten feet past their neighbor’s back wall even if that means it’d cover less than the allowed lot coverage.
This ruling is an extension of the zoning commission's 2015 decision to restrict both the height of rowhouses and the number of units an owner can build into one in these same zones. Some residents also pushed for it during 2013 and 2014's Zoning Regulations Review public hearings.
Limiting rear additions means limiting DC’s housing supply
This new rule applies to a large majority of the residential zones in the District that contain attached and semi-attached housing units. Capitol Hill, Georgetown, Woodley Park amongst others are included in the zones affected.
Let’s imagine you’ve purchased a beautiful Wardman townhouse on a big lot, but that two-room deep row house just doesn’t fit the bill for today’s need for a multipurpose family room. You decide you want to go back 12 feet to get that extra space. Zoning code stipulates that you can cover 60% of your lot, and your lot coverage with the addition would only be 50%.
The issue now is that if your neighbors’ walls on both sides are even with your rear wall, you’ll be limited to a 10-foot addition unless you go through a special exception process.
Many of the row houses in the city are not built for today’s growing families. The family rooms, mudrooms, powder rooms, master suites and larger kitchens of today’s modern home and lifestyle won’t fit in the small footprints of many of DC attached homes. Ten feet just won’t be enough in some cases. This new rule may mean growing families look elsewhere for a house.
Where once the amount that a person could extend depended on the size of their lot and how much of it their house already covered, they’ll now be limited based on the size of their neighbor’s structure.
The lot coverage max was an egalitarian limit based on the lot. Now it’s based on the structure, and is a little bit of the luck of the draw. There has to be a happy medium. Perhaps zoning that reflects a bonus for side courts?
This rule, while protecting neighboring properties, limits what the city needs so desperately: more housing units. Good development that respects the streetscape and neighbors while providing quality housing is essential. Creative elements like side courts and rear courtyards can help alleviate the neighbor’s light and air worries.