Backyard Infill: A Useful Tool for Housing Affordability

As cities around the country struggle to meet demand for housing, many are exploring the creation of backyard housing units as a tool to increasing density without impacting the feel of a neighborhood. In Cambridge, this approach is nothing new: creation of new homes in the backyards of existing properties is a long-standing tradition, and has been a key part of the City’s efforts towards creating affordable housing for generations, and with appropriate zoning, could provide a cost-effective way to achieve the same goals in our current struggle to create affordable housing.

Backyard homes have a nice property for neighborhoods: where front buildings are maintained, they offer an opportunity for builders to create new homes without impacting the look and feel of a street. Harvard Place is an excellent example of this: this mansard house style structure, at 273 Harvard St., was renovated and repaired from its status as a vacant building. At the same time, a dense assisted living facility for seniors was created behind the front house. In this way, the streetscape was almost unchanged, while 21 new homes for low-income seniors were created, and a historical part of Harvard Street restored to its original facade from a degrading vacant structure.

Possibilities like this abound in some parts of Cambridge. The standard sized lot when Cambridge was originally plotted out was typically 5000 square feet -- 50’ of frontage with a 100’ depth. However, in some parts of Cambridge -- especially historically single family zones like parts of West Cambridge -- there are lots significantly deeper than this, up to 200', creating empty spaces that are often large enough to contain significantly more homes with relatively minimal impact.

One example of such a property that is currently for sale is 34 Buckingham St., in West Cambridge. This oddly shaped property has an especially deep lot -- nearly 220’ deep at its deepest point. The backyard is heavily screened from its neighbors by high shrubs, creating a highly separated space which is ideal for construction of new homes with minimal impact on the experience of others.

Under a zoning proposal like the affordable housing overlay, this property -- a single family home currently on the market for $2.9M -- could potentially be subdivided and create a backyard space of 5000 square feet at a relatively low land cost. This space would be constrained by setbacks in this odd-shaped lot, but even with that being the case, the resulting back property would make it possible to create 6-8 new affordable homes -- while having almost no impact on the visible street line of the neighborhood.

Because of the narrow frontage on the street, these homes would likely not even be visible to a passerby: the historic building on the front of the property would be maintained, probably still fetching a significant price. However, in the backyard, a more dense structure would be possible, creating an opportunity for a small number of families to benefit from living in an area with a strong tree canopy, good bus connectivity, and quick access to Harvard University and only a 15 minute walk from Harvard Square.

While this type of development would not be financially feasible for a for-profit developer--even under the proposed affordable housing overlay, the number of units required to make such a development break even would not be possible--for non-profit organizations focused on creating affordable housing, this could potentially be a worthwhile venture: splitting the property likely leaves the front property as having a value in the realm of at least $1.5M-$2M, meaning that the back lot would be in the area of $1M for 6-8 units, or around $150k/unit for acquisition cost of the land, within the area where non-profits are able to invest. (Some have exaggerated the amount of construction that would be possible under such an arrangement, ignoring the realities of the affordable housing overlay; on a small, rectangular 5000 square foot property like this, the total area available for development under the overlay would likely amount to less than 8000 square feet.)

The area is already surrounded by high hedges and trees significantly taller than the 45’ height limit allowed under the affordable housing overlay; and the front building -- already 38’ tall -- would limit any significant visibility of the buildings behind it (just as Harvard Place does). Overall, this type of building would likely be almost entirely hidden from view -- just as so many backyard homes in Cambridge already are.

All in all, this would be a great opportunity for the community to take advantage of some of the historical relics of privilege to fight in favor of greater equity in our community.

Backyard infill can’t solve our affordable housing crisis on its own. Despite the “Yes in my Backyard” moniker, too few of Cambridge homes have backyards to say “yes” in. But taking advantage of these backyards where they are available to expand our opportunities for affordable housing, with minimal impact to existing neighborhoods and communities, is taking advantage of an opportunity that we shouldn’t turn away from.