Understanding Ithaca's 2025 ADU Ordinance: What Homeowners Need to Know

In May 2025 the City of Ithaca adopted an ordinance that makes accessory dwelling units an allowed use in several residential zones. For many homeowners, that means a backyard cottage or basement apartment is now a realistic option.

Where ADUs are allowed

ADUs are permitted in the R-1, R-2 and R-3 residential zones, with typical minimum lot sizes of roughly 6,000, 4,000 and 3,000 square feet respectively. Check the city zoning map to confirm your district.

Size and placement

Units are capped at an 800 sq ft footprint and two stories or 20 feet in height. Side and rear setbacks generally fall between 5 and 10 feet, and combined lot coverage usually can't exceed 40%.

Parking and occupancy

Parking requirements are reduced or waived in most zones, particularly near transit. Some properties may need the owner to live in either the main house or the ADU — confirm the current rule for your lot.

Getting started

Begin with a pre-application meeting with the Planning Department, then prepare site plans and drawings. Review typically takes four to eight weeks.