Coastal Zoning Overlay District in Effect

Late last month, Acting Mayor Kim Janey signed a new Coastal Zoning Overlay District into effect requiring new development in Charlestown and other Boston coastal neighborhoods to take additional steps to limit the damage and displacement related to the impacts of coastal storms and sea level rise.

Based upon climate modeling, 40-inches of sea level rise in Charlestown so the new Zoning Overlay (Article 25A of the Boston Zoning Code) will provide new definitions and standards for building dimensions and uses to facilitate flood resilient design for new projects and building retrofits.

In Charlestown the areas subjected to the new zoning include the neighborhood’s waterfront along the Mystic River, the area around the Schraft’s City Center wrapping around to Rutherford Avenue area and Mishawam as well as the Navy Yard along the Boston Harbor.

Janey said the new zoning goes beyond the areas identified in FEMA flood maps, applying to areas of Charlestown and the City that could be inundated during a major coastal storm event, known as a 1 percent chance flood event with 40-inches of sea level rise and promotes resilient planning and design, provides consistent standards for the review of projects, and maximizes the benefits of investments in coastal resilience.

“We must take the steps that will better protect our neighborhoods from the increasing threat of coastal storms and sea level rise,” said Janey. “By requiring developers to do more in vulnerable areas, we are protecting our infrastructure, our jobs, and our homes.”

Boston Planning and Development Agency Director Brian Golden said for Boston to grow and thrive for generations to come, the city must ensure that buildings constructed today are resilient and protected from the impacts of climate change.

“By updating our zoning code to go above and beyond the FEMA flood maps, Boston is leading the way in not only preparing for the storms of today, but the storms of tomorrow,” said Golden.

All development projects subject to BPDA’s Article 80 Large and Small Project review will be required to undergo Resilience Review, and comply with the Coastal Flood Resilience Design Guidelines. In 2019, the BPDA adopted Coastal Flood Resilience Design Guidelines to provide clear strategies and best practices for developers, business owners, and residents to respond to climate change.

The new guidelines are Intended to prevent flood damage by elevating building occupiable space, flood proofing areas beneath flood elevations, and promoting health and safety by preventing uses such as living space below the flood elevation.

“In Boston, we know that our most vulnerable communities are disproportionately bearing the burden of the climate crisis,” said Chief of Environment, Energy and Open SpaceReverend Mariama White-Hammond. “As a City, we must work together to take the crucial steps to protect all of our residents from the effects of climate change. I am grateful to Mayor Janey and the BPDA for updating zoning measures to enhance our collective resilience.”

The new zoning regulations include:

Building Height: Projects undergoing Resilience Review will have their height measured from two feet above the Sea Level Rise Base Flood Elevation (SLR-BFE), rather than at grade, which is what current zoning requires.

Building Setbacks: Projects will have allowances to extend into side yard, rear yard, and front yard setbacks for structures needed for vertical circulation, such as stairs or ramps to get from surrounding grade to a higher first floor elevation. There are also allowances for side yard and rear yard encroachments for new structures to house mechanical systems to ensure they are not located in basements or beneath the Sea Level Rise Design Flood Elevation (SLR-DFE), which consists of the SLR-BFE plus one to two feet based on type of use.

Lot Coverage and Required Open Space: The structures needed for vertical circulation and mechanical systems referenced above will be excluded from measurement of lot coverage and open space

Gross Square Floor Area: Will exclude structures needed for vertical circulation and areas devoted to flood protection measures.

Limitations on Use Below the Sea Level Rise Design Flood Elevation: For health and safety purposes, uses beneath the SLR DFE are limited to access for vertical circulation structures; flood prevention measures, storage, and parking.

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