Zoning & Size Limits
| Requirement | Cambridge, MA | Quincy, MA |
|---|
| Allowed Zones | All residential districts - Cambridge eliminated single-fami | One ADU by right in single-family zoning districts (internal |
| Max Size (Detached) | 900 sq ft or 50% of primary dwelling, whichever is less (MA state by-right cap) | 900 sq ft or 50% of the principal structure's gross floor area (per 760 CMR 71.02), whichever is less; minimum 320 sq ft for a detached ADU |
| Max Size (Attached) | 900 sq ft or 50% of primary dwelling, whichever is less (MA state by-right cap) | 900 sq ft or 50% of the principal structure's gross floor area, whichever is less |
| Max Height | No ADU-specific cap - an ADU may match the princip | Detached ADUs limited to one story (city guideline |
| Parking Required | None - Cambridge abolished all parking minimums citywide in | 1 additional off-street space required only if the ADU is ou |
| Owner Occupancy | Not required (prohibited under MA Affordable Homes Act / 760 | Not allowed — prohibited statewide by the Affordable Homes A |
Setback Requirements
| Setback | Cambridge, MA | Quincy, MA |
|---|
| Rear Setback | 5 ft base (ADU setbacks may not be stricter than principal/accessory standards under 760 CMR 71.03) | Detached ADUs must meet the principal-structure yard setbacks in QZO Table 4.1 — varies by district; Confirm with Quincy Inspectional Services |
| Side Setback | 5 ft base | Per QZO Table 4.1 (district-specific) — Confirm with Quincy Inspectional Services |
| Front Setback | 10 ft base | Per QZO Table 4.1 (district-specific) — Confirm wi |
Permits & Timeline
| Detail | Cambridge, MA | Quincy, MA |
|---|
| Permit Timeline | 60-90 days | Standard building-permit review; typically 4-8 weeks — Confirm with Quincy Inspectional Services |
| Permit Fees | $3,500-$5,500 | Valuation-based building permit fee — Confirm with Quincy Inspectional Services |
| Impact Fees | $1,500-$2,500 | None listed in the ADU guidelines — Confirm with Quincy Insp |
| Pre-Approved Plans | Not available | None — Quincy does not offer a pre-approved ADU pl |
Construction Costs
| Cost | Cambridge, MA | Quincy, MA |
|---|
| Avg Build Cost | $210,000-$420,000 | $250,000-$425,000 |
| Cost Per Sq Ft | $220-$440 | $350-$550 |
| Garage Conversion | $105,000-$230,000 | $150,000-$250,000 |
| Prefab ADU | $160,000-$340,000 | $180,000-$350,000 installed (site work, foundation, and utility connections extra — confirm with manufacturer) |
Rental Income Potential
| Rental | Cambridge, MA | Quincy, MA |
|---|
| 1BR Avg Rent | $1,900-$2,500/mo | $2,200-$2,700/mo |
| 2BR Avg Rent | $2,300-$3,400/mo | $2,700-$3,300/mo |
| Short-Term Rentals | Not permitted | No — Quincy's ADU guidelines expressly prohibit using an ADU |
| Est. ROI | 5-7% annual return | 5-8% annual return |
Which City Is Better for ADUs?
Cambridge scores 8/10 while Quincy scores 6/10 on our ADU-friendliness index.
Cambridge edges ahead overall. Both cities offer viable ADU development opportunities — the best choice depends on your specific property, budget, and goals.
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