Boston's Zoning Code limits the percentage of a lot that can be covered by buildings and impervious surfaces. Residential zones typically allow 40-60% maximum lot coverage. Open space requirements ensure a portion of each lot remains permeable. The BPDA and ZBA review projects that exceed lot coverage limits.
Lot coverage in Boston is regulated through the Zoning Code's Floor Area Ratio (FAR) limits and maximum building coverage provisions. In residential districts, maximum building coverage typically ranges from 40% in low-density zones to 60% in higher-density areas. The code also establishes usable open space requirements — a percentage of each lot that must remain as landscaped, permeable ground. FAR limits control the total floor area of buildings relative to lot size, effectively constraining building bulk. In mixed-use and commercial districts, lot coverage limits are generally more generous, with some downtown areas having no maximum coverage. Impervious surface coverage is increasingly scrutinized due to stormwater management requirements, and BWSC may require on-site infiltration for projects exceeding certain impervious thresholds. Accessory structures (garages, sheds) count toward lot coverage. The ZBA may grant variances for lots where existing non-conforming coverage makes compliance impractical. The BPDA reviews lot coverage as part of Article 80 project review.
Exceeding lot coverage limits without a variance is a zoning violation. ISD may issue stop-work orders and require modification of plans. Structures built exceeding coverage may need to be reduced or removed. Daily fines apply until compliance is achieved.
Boston, MA
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See how Boston's lot coverage limits rules stack up against other locations.
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