Ithaca ADU Quick Start Guide
Essential information for homeowners considering an ADU in Ithaca, NY.
What is an ADU?
An Accessory Dwelling Unit (ADU) is a secondary housing unit on a single-family residential lot. Also known as in-law suites, granny flats, or backyard cottages, ADUs provide independent living space with their own entrance, kitchen, and bathroom.
- Detached backyard cottage
- Attached addition to your home
- Garage conversion
- Basement apartment
- Attic conversion
Ithaca ADU Rules at a Glance
Max ADU Size
Up to 850 sq ft
Setbacks
5 ft rear & side
Height Limit
24 ft for detached
Owner Occupancy
Not required in Ithaca
Parking
1 space may be required
Short-Term Rental
Check local rules
Your 5-Step Path to an ADU
Assess Your Property
Check zoning, lot size, and setback requirements for your address.
Choose Your ADU Type
Select the ADU format that fits your property, budget, and goals.
Design & Plan
Work with a designer to create compliant, functional plans.
Permits & Approvals
Submit to the City of Ithaca Building Department. Allow 4–8 weeks.
Construction
Build with a licensed contractor. Timeline: 3–9 months depending on type.
Typical Costs in Ithaca
Garage Conversion
$50K–$120K
Timeline: 3–5 months
Basement ADU
$60K–$130K
Timeline: 3–6 months
Attached Addition
$120K–$220K
Timeline: 5–8 months
Detached Cottage
$150K–$300K
Timeline: 6–12 months
Costs vary by site conditions, finishes, and design complexity. Use these ranges for early planning, then request a detailed estimate for your property.
Want a plan template?
The City of Ithaca is developing approved template ADU plans. In the meantime, our team can create code-compliant plans tailored to your lot.
Ready to Start Your ADU Journey?
Our team knows Ithaca's regulations inside and out. Let's talk about your property.