Labs Experiment 005 Building
Test the zoning: Arlington Heights
The town is working on a new Heights Business District to replace the patchwork of business zones along Mass Ave and Park Ave, with a goal of bringing it to Town Meeting in 2027. Zoning is a stack of rules: how tall, how much floor area, how far back, how many parking spaces, how much open space, and what can go inside. No single rule tells you what can be built. Whichever one runs out first decides.
Pick a real Heights lot, choose a set of rules and turn the dials. The drawings and the “Which rule wins” list show what the rules allow and which one is holding the building back.
4. Turn the dials Custom rules
Which rule wins
How the rules fight over a lot
Height
Limits come in two forms, feet and stories, and a building has to meet both. Shops want a tall ground floor (we assume 15 feet), homes need about 10½ feet a floor, so a 50-foot cap can hold four stories but not five.
Step-backs
Above the third story, Arlington requires the street wall to step back 7½ feet. On a shallow lot that can cost a fifth of every upper floor.
Floor area ratio (FAR)
FAR caps total floor space as a multiple of lot size. A FAR of 3.0 on a 10,000-square-foot lot allows 30,000 square feet, however it’s stacked. When FAR is low, extra height allowance doesn’t matter.
Setbacks
Front, side and rear setbacks shrink the footprint. Business districts let mixed-use buildings sit at the sidewalk, but the rear yard grows to 30 feet for the fourth story and up when the back of the lot faces houses.
Parking
One space per home and one per 300 square feet of shops (after the first 3,000). A surface space with its share of the aisle takes about 325 square feet, so on a small lot every space you add takes land away from the building, which means fewer homes, which means fewer spaces needed. The tool finds where that loop settles.
Open space and density
Mixed-use buildings in business districts must keep 15% of the lot as landscaped open space (rooftops and balconies can count). Some lots also have a minimum lot area per home, which caps the number of homes no matter how big the building is.
Use and permits
In today’s business districts, a mixed-use building, an apartment building, and shops or offices of 3,000 square feet or more all need a special permit. The MBTA overlay allows apartment buildings by right, with site plan review. The Heights draft would also allow shops and restaurants over 3,000 square feet by right.
Where the Heights rezoning stands
- 2019: The Arlington Heights Neighborhood Action Plan recommends replacing the Heights’ business districts with one new district.
- October 29, 2024: At a community forum, staff present the plan’s 2018 recommendations: five stories, no front or side setback, a 20-foot rear setback, 5,000-square-foot lots and 800 square feet of lot per home. Asked whether an affordable housing overlay could raise the limit to seven stories, the town planner said yes (meeting notes, YourArlington).
- Early 2025: The town runs a Heights visioning survey. In April, the Redevelopment Board says the Heights and East Arlington rezonings will come to Town Meeting in 2026 (April 7, 2025 minutes).
- November 5, 2025: A second forum shares proposed district boundaries and a vision statement.
- August 10, 2026: Staff present a draft to the Redevelopment Board for feedback (Inside Arlington). The town’s project page now aims for Town Meeting in 2027. The July 27 draft rezones the Heights to the existing B5 district, with B2A on the edges, and adds the MBTA overlay’s bonuses. The Board supports using existing business zoning (August 10 slides).
- September 2026: A one-pager for Town Day proposes a single B5 zone from the Lexington line to Foot of the Rocks, replacing B2, B2A, B3, B4, T, R2, R3 and R5. It would also allow shops and restaurants over 3,000 square feet by right. A Stantec study found enough on-street parking, and a Parking Benefits District with meters is proposed. A revised draft (v4) went to a committee on September 28.
- Next: a community forum on November 5 at 7 p.m. at Peirce Elementary, a warrant article in January 2027 and Town Meeting in April 2027.
Sources and limits
- Today’s rules come from the town’s Zoning Bylaw, as amended through April 28, 2025: Section 5.5.2 (business district lot, yard, open space, height and FAR tables), 5.3.17 (upper-story step-backs), 5.3.19 (reduced height buffer), 5.5.3 (uses) and 6.1 (parking, including the 3,000-square-foot exemption for mixed use and the reduction to as little as 25% with a transportation plan). The tool uses each district’s mixed-use row and reads “20,000 sq. ft.” as lot size. Changes from the 2026 Town Meeting aren’t included.
- MBTA overlay rules come from Section 5.9, adopted by the October 2023 Special Town Meeting (Article 12 text): four stories and 52 feet on Mass Ave, rising to six stories and 78 feet with ground-floor shops; 15-foot front, 5-foot side and 20-foot rear setbacks; no FAR, lot-area-per-home or open space minimum; no parking required for shops. The overlay covers mapped parcels near Mass Ave and Broadway, mostly outside the business districts, so for most lots here it’s a what-if.
- Heights draft (B5) uses the B5 tables and bonuses in the town’s July 27, 2026 draft (v3): for mixed use, 60 feet and five stories (50 and four in the height buffer, or 40 and three on lots over 20,000 sq ft), FAR 3.0 (2.8 over 20,000 sq ft), no front or side setback, the same rear setbacks as today, 15% open space and 700 sq ft of lot per home on lots over 20,000 sq ft. With an active ground floor it rises to six stories and 78 feet. The draft keeps today’s parking rules (Section 6.1). We left out B5’s apartment-only row, and the September 28 v4 draft is a scanned image we couldn’t check, so numbers may have changed. It’s a draft, not adopted zoning.
- Lots are real Heights business parcels from the town’s Parcels with Assessor Info layer (FY2026), drawn as rectangles: width is the estimated street frontage from the Question 7 experiment and depth is lot area divided by width. Real lots are irregular.
- Building assumptions: a 15-foot ground floor and 10½-foot upper floors; 80% of floor area becomes homes (the rest is halls, stairs and walls); about 325 square feet per surface parking space including aisles. The building fills the width between side setbacks. The tool searches every depth and story count and keeps the one with the most homes.
- Property tax on new homes assumes $650,000 of assessed value per home, the FY2026 average for the 39 condominiums at 88 Park Ave in the Heights, at the FY2026 rate of $10.67 per $1,000 (classification hearing). Shop space isn’t counted, so the estimate runs low.
- Not modeled: special permits that adjust setbacks or parking, affordable-housing requirements and bonuses, the 26-foot, two-story minimum for new business buildings, corner-lot rules, driveways, loading, building code, cost and whether a project would pay for itself. This is a tool for seeing how rules interact, not a zoning determination.