Building Reuse: Lowest-Cost Path to New Housing

Our ongoing housing crisis requires the creation of new homes in order to provide for the needs of Cambridge residents, but new homes don’t always mean new construction. The proposed 100% Affordable Housing Overlay will support more than just new construction, by relaxing zoning rules across the board. With relaxed zoning rules, it will be easier to create new homes in the existing buildings we have -- something made difficult or impossible by the restrictive zoning in the city today.

This former single-family home in North Cambridge was purchased and converted to 14 units of supportive housing for disabled, formerly homeless women. Offering on-site service coordination, Duley House helps residents move from transitional to permanent, affordable housing. This type of development is not allowed without special permission under today's zoning rules -- and developments like this are often delayed by years of lawsuits from neighbors.

The most cost-effective way to create new homes is to reuse existing buildings. New construction means new materials, new labor, and generally starting from a blank slate -- and is the most expensive way to create new homes. Typical new construction costs for a multi-unit building end up being in the realm of $300 per square foot -- drastically exceeding the cost of renovating existing buildings. With the variety of housing stock available in Cambridge, all-new construction is not the most likely path to creating new affordable housing in Cambridge. Instead, building re-use is common: creating new homes on existing properties, through a combination of thoughtful additions and re-dividing internal spaces. The end result is that many affordable housing developments maintain a street-facing facade of an existing building, while extending the property with additional buildings or extensions to accommodate more homes. Preserving existing buildings is often the most cost-effective approach to creating new homes, and is likely to be pursued in many cases.

Currently, it is rarely possible to extend the number of units on an existing property, even if there is room on the property to add an extension or even build another building. More than 80% of Cambridge’s residential lots are legally prohibited by zoning restrictions from adding an additional unit, even if that unit is in the existing building. These limitations make creating new housing in existing buildings impossible in the vast majority of the residential districts of the city. In the past, much of Cambridge’s effective affordable housing has resulted from converting existing buildings, especially for supportive housing -- housing communities that help support at-risk populations - featuring communal spaces and on-site service coordination. Cambridge's rules makes this type of development impossible under current zoning.

Beyond unit size limits, more than 50% of existing Cambridge properties exceed the current limits on maximum floor area for their lot. For all of these properties, this means that extending the property in any way requires permission from the zoning authorities in Cambridge -- and even if that permission were to be granted, it would be something that could be challenged by neighbors in court. For example, if an affordable housing developer were to want to extend a kitchen space to allow for greater flexibility in creating a communal cooking area to support a greater number of residents, this would not be possible for the vast majority of existing homes under Cambridge’s zoning rules.

The 100% Affordable Housing Overlay corrects these limitations. By eliminating restrictions on the number of units allowed on a given sized lot entirely, it becomes possible to convert existing buildings to create significantly more homes for individuals or families -- allowing the possibility of creating opportunities for new types of affordable housing that have previously been rare in Cambridge. It loosens restrictions on allowed building size -- allowing for buildings to take up more of the lot, and meaning that most changes to support needs of new residents would be possible which are not today. Contrary to claims that the proposal would necessitate the demolition of buildings, these changes allow for the preservation of buildings that might otherwise be cost-ineffective to maintain and would result in demolition. By eliminating the risk costly and time consuming lawsuits, new developments become possible under the overlay which could never happen today.

In 1998, this Harvard Manor nursing home had been vacant for several years and was in deteriorating condition. It was purchased by CASCAP and restored to the original 1860s mansard-style house while adding a large addition onto the back. Developments like this help preserve existing buildings and provide affordable housing at the same time.

New construction is expensive. Re-using old buildings is a valuable way for developers building affordable housing to reduce their costs; by re-using existing buildings, developers can drastically reduce the total cost of a project. Under current zoning, we see very little of this because the vast majority of existing buildings are not allowed to extend their current footprint by today's rules. The 100% Affordable Housing Overlay proposal would make reuse and extension of existing buildings possible. For the creation of new affordable housing, re-using existing buildings is often the most cost-effective approach, and allowing for these type of developments will allow for creation of new affordable housing that would otherwise simply never be created in the city.

The Affordable Housing Overlay's zoning changes will likely help enhance existing properties, creating more homes while maintaining many existing buildings -- simply because that's the most cost effective thing for developers to do.

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Under Cambridge's proposed Affordable Housing Overlay, affordable housing developments would be allowed to exceed the height allowed under current zoning in many districts. However, there's been a lot of misunderstanding of what this would look like in practice. To help give a sense of what these increase look like, here are some examples in context of their street to give a sense of what the allowed height increases could look like throughout Cambridge.

In Cambridge, eliminating single family zoning without changing any other zoning requirements achieves relatively little direct impact because of how our zoning rules have been designed. By combining the elimination of single family zoning and removal of other restrictive zoning elements, the proposed Affordable Housing Overlay could open the door for thoughtful redevelopment of a small number of parcels anywhere in the city -- including in the single family zones that we have today.