- Max size800 sq ft
- Owner occupancyRequired
Madison, CT permits accessory apartments under Section 24 of the Zoning Regulations. The framework is built around conversion: an existing one family dwelling, an addition, or an accessory building can be converted to a one family dwelling with an accessory apartment. The cap is the lesser of 800 square feet or 30 percent of the primary dwelling's floor area, with a 400 square foot minimum and an occupancy limit of three people per accessory unit. Madison's regulations predate Connecticut Public Act 21-29, and the town retained more restrictive local rules on parking, annual renewal, and architectural compatibility.
Status
- Adoption status
- Active. Madison Zoning Regulations Section 24.
- Governing ordinance
- Madison Zoning Regulations, Section 24 (Accessory Apartments)
- Key differentiator
- Conversion-based framework, 3 person occupancy cap, annual renewal requirement, and architectural harmony review. The town's Section 24 predates PA 21-29 and retains tighter local rules.
Eligibility
Where ADUs are allowed
- Zoning districts permitted
- Residence Districts (Section 3) and Rural Districts (Section 5)
- Lot type
- Lots with an existing one family dwelling, accessory building, or addition that can be converted
- Limit per property
- One accessory apartment per lot
Types allowed
- Attached ADU (converted addition)
- Yes
- Accessory building conversion
- Yes
- Purpose built new construction
- Conversion-based regulation; new build standalone path is less common and should be confirmed with Madison P&Z
Size and placement
Size limits
- Minimum sq ft
- 400 sq ft
- Maximum sq ft
- 800 sq ft, or 30 percent of the primary dwelling's floor area prior to the accessory apartment, whichever is less
- Maximum occupancy
- 3 people
Setbacks
- Setback requirements
- Section 24.3 places no additional setback or coverage restrictions; same as principal dwelling
Rules for use
Parking
- Total parking required
- At least 3 off street vehicle spaces to serve the primary and accessory unit combined
Owner occupancy
- Required
- Yes
- Annual renewal
- Section 24.4.3 requires annual renewal and an affidavit each year
Rental use
- Short-term rental
- Not specifically addressed in the Section 24 excerpt retrieved
- Long-term rental
- Permitted, subject to owner occupancy and annual renewal
- Architectural review
- Section 24.3.5 requires the accessory apartment to be in harmony with the original character; Section 24.3.6 prohibits new exterior front doors
How to apply in Madison
- Default pathway
- Administrative permit through Madison Planning and Zoning
- Renewal
- Annual renewal and affidavit required
- Contact
- Madison Planning and Zoning Department
Important details
- Annual renewal: Madison is one of the few Connecticut towns that requires accessory apartment permits to be renewed annually with a notarized owner occupancy affidavit each year.
- Three-person occupancy cap: Section 24.3 limits the accessory unit to 3 occupants total.
- Three vehicle parking requirement: combined principal plus accessory must provide at least 3 off street parking spaces, exceeding the PA 21-29 default of 1 ADU space.
- Conversion based: Section 24.2 references conversion of existing structures rather than purpose built new construction. Standalone new builds may need additional review.
Frequently asked questions
Where in Madison are accessory apartments allowed?
In residence districts (Section 3) and rural districts (Section 5) via administrative permit. Madison's framework is built around converting an existing dwelling, addition, or accessory building rather than purpose built new construction.
What's the size cap?
Lesser of 800 square feet or 30 percent of the primary dwelling's floor area prior to the accessory apartment, with a 400 square foot minimum. The accessory unit is also limited to 3 occupants.
Do I really need to renew every year?
Yes. Section 24.4.3 requires annual renewal and a notarized affidavit confirming owner occupancy each year. This is a tighter cadence than most Connecticut towns and is one of the provisions Madison's own analysis flags as exceeding the Public Act 21-29 default.
Sources (3)
Last reviewed 2026-04-28. Local rules can change — verify the latest details with the Madison planning department, or book a free consultation with our team before starting your project. This page is informational and is not legal advice.