Boston, MA Building Setbacks & Zoning: Setback Rules (2026)
Key Facts
- S-.3 district front yard
- 25 ft minimum
- S-.3 district side yard
- 12 ft minimum
- S-.3 district rear yard
- 40 ft minimum
- Exact figures by district
- Table B, Section 13-1
- Front yard structures allowed
- Fences ≤5 ft, steps, signs only
- Enforced by
- Building Commissioner
Summary
Boston's Zoning Code sets a separate front, side and rear yard minimum for every district in Table B of Section 13-1. In the base S-.3 single-family district, for example, a lot must carry a 25-foot front yard, a 12-foot side yard and a 40-foot rear yard, with narrower or wider minimums specified district by district.
Minimum lot size, minimum lot area per dwelling unit, minimum lot width, maximum height of buildings, minimum usable open space per dwelling unit, minimum front yard depth, minimum side yard width, minimum rear yard depth, minimum setback distance of parapet from any lot line, and maximum percent of rear yard occupied by accessory buildings for each class of use shall...be as specified in the following table. ... S-.3 1 family detached 9,000 none 70 0.3 2½ 35 none 25 12 40 none 25
Full Breakdown
be as specified in the following table,' Table B. 5 stories/35 ft, front yard 25 ft, side yard 12 ft, and rear yard 40 ft; other districts carry their own figures, for example H-1-40 lists a 20-foot front yard. Article 18 defines the front yard itself: Section 18-1 requires the area between the street line and the yard depth line be kept clear except for fences and walls no taller than five feet, steps, terraces and open unroofed porches projecting no more than three feet, and signs conforming to Article 11.
Section 18-2 can override the table minimum with the block's 'modal front yard depth,' the setback shared by the greatest lot frontage on that side of the street, calculated lot by lot. Article 20 governs the rear yard the same way: Section 20-1 keeps the area between the rear lot line and the required depth free of structures except as Sections 20-2 and 20-3 allow (accessory buildings and limited projections). Article 21 layers on an additional parapet setback for taller buildings above the base yard requirements, tied to floor area ratio.
Violations & Fines
The Building Commissioner enforces the Zoning Code under Section 5-1. A structure built without meeting the applicable Table B yard minimum becomes a nonconforming building under Section 13-3, and any later alteration or extension of it must conform to the dimensional requirements and cannot worsen the existing nonconformity.
Frequently Asked Questions
Where do I find Boston's exact setback minimums for my zoning district?
Can I build anything inside my required front yard?
What if my neighbors' houses aren't set back the full distance the table requires?
What happens if I build without meeting the required yard?
Sources & Official References
Other rules in Boston
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Setback Rules in Nearby Cities
How other cities in this county handle setback rules.