Gross Square Floor Area will exclude structures needed for vertical circulation and areas devoted to flood protection measures.Current research shows that sea level rise is a real threat, and is one. Structures needed for vertical circulation and mechanical systems referenced above will be excluded from measurement of lot coverage and open space. Though we rarely see it spelled out, NAVD stands for National Geodetic Vertical Datum.An allowance for side 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).An allowance for side and rear yard encroachments for structures, such as stairs or ramps needed for vertical (access) circulation, due to a higher first floor elevation.Building heights to be measured from 2 feet above the Sea Level Rise Base Flood Elevation (SLR-BFE), rather than at grade. Many coastal communities in the US use base flood elevation (BFE) maps for the 100-year return period, specified on Federal Emergency Management Agency (FEMA) Flood Insurance Rate Maps (FIRMs), to design structures and infrastructure.The intent of the new overlay district is to facilitate flood resilient design and prevent flood damage by elevating buildings’ occupiable space and floodproofing areas beneath flood elevations. 1 FEMA COASTAL FLOOD HAZARD ANALYSIS AND MAPPING GUIDELINES FOCUSED STUDY REPORTS 1 INTRODUCTION 1.1 CATEGORY AND TOPICS This report describes a proposed approach for the development of new FEMA Guidelines for the determination of stillwater levels in coastal areas. Based on climate modeling, Boston is anticipated to experience a 40-inch sea-level rise by 2070. Areas subject to inundation by the 1 annual chance flood event with additional hazards due to storm induced velocity wave action. Protect yourself and your family Make a plan for your household, including your pets, so that you and your family know what to do, where to go, and what you will need to protect yourselves from flooding. The new zoning overlay includes areas beyond those identified in current FEMA flood maps. To review an elevation certificate call 84 (County) or 84 (City). Article 25A provides a new Coastal Flood Resilience (CFR) Zoning Overlay District requiring new development and retrofits to take steps to limit building damages due to coastal storms and sea-level rise.

As part of The City of Boston’s commitment to climate resilience, on September 13, 2021, the Boston Planning & Development Agency (BPDA) approved Article 25A of the Boston Zoning Code.

Base flood elevation sea level