What Are Accessory Dwelling Units and Does Connecticut Allow Them?

January 30, 2023


Accessory Dwelling Unit Laws in Connecticut

Families come in a variety of shapes and sizes. More younger family members are living at home for longer. Older family members are also beginning to move in with younger members to be taken care of or to help with childcare. Regardless of what your family looks like, it’s important to have space for them in your home. Accessory dwelling units (ADU) are one way to add space to a single-family home. When considering adding on an ADU or rental property, there are a lot of things to think about. What exactly are ADUs, what benefits will it have on your home, and what are the laws about them in Connecticut? 

What are Accessory Dwelling Units?

ADUs go by many names. Mother-in-law suites, backyard cottages, accessory apartments, and granny pods are just a few. 

At their heart, ADUs are a second, smaller house or apartment that is either attached to or detached from the primary residence. For example, often people have an ADU in their basement or backyard. The size and location of ADUs on a property are typically determined by that municipality’s zoning regulations. 

There will be a kitchen, bedroom, bathroom, and living room  area. Each dwelling can be made to cater to a specific person or family size.  

Building ADUs can vary in cost depending on where you build it and how big you build it. Creating one in your existing house, like the basement, can be cheaper because you don’t have to deal with adding walls, foundation, or plumbing. If you build one detached from your home , you do have to pay for new plumbing and electrical hook ups, it can be more customizable but at a more costly rate.

Benefits for Single Family Homes


Accessory Dwelling Units for Single Family Homes

If you have a single-family home, it can be hard to house extra family members or children who need to live at home longer but want their own space. One of the biggest benefits to owning an ADU is that you create space for family members who need it. 

Depending on the location of the dwelling, you can also rent it out to make extra income. ADUs can increase the value of your property by 20%-30%. It can also appeal to more buyers when you go to sell your home.

These dwellings can also help reduce gentrification and desegregate neighborhoods by giving opportunities to people who otherwise might not be able to afford to live in certain neighborhoods. 

Accessory Dwelling Unit Laws in Connecticut 

The laws around accessory dwellings in Connecticut changed in 2021. The legislation, Public Act 21-29, requires towns to designate specific zones where ADUs are permitted as-of-right, either attached to or detached from the single-family house. 

However, towns can opt out and set their own requirements for ADUs or not allow them at all. One exception to this is that towns cannot require a minimum square footage. Checking local requirements before building will ensure you aren’t breaking any laws. 

ADU Laws in Norwalk, Connecticut

In Norwalk, CT ADU regulations were adopted in 1982, with updates adopted by the Planning & Zoning Commission at their December 8, 2022 meeting. There are currently 259 accessory apartments in the city. After reviewing the new state laws, Norwalk agreed with the majority of the new state law. In fact, many of Norwalk’s current ADU regulations already comply with the law, including:

  • Permitted in all zones where the primary use of a property is a single-family residence
  • ADUs allowed to be attached to or within a single-family residence
  • Setbacks and building frontage must be less than or equal to that required for single family residences
  • No more than one parking space for an ADU  
  • A familial, marital or employment relationship between accessory apartment
  • occupant and single family residences owner is not required 
  • Separately billed utilities is not required

The one area of concern for Norwalk was the allowed height of a detached ADU, which the new state law requires to be the same as what is allowed for single-family houses. In Norwalk, the maximum allowable height for a detached ADU varies between 15’-20’, depending on the location of the detached ADU.

Additionally, the Norwalk Planning and Zoning Commission updated the design and landscape standards for ADUs, stating, “For detached accessory dwelling units, a buffer, consisting of fencing and/or vegetative screening that includes a mix of evergreen and deciduous trees as well as foundation plantings, shall be required between the accessory dwelling unit and the nearest side and rear property lines. The final determination on the location of the screening and the required materials shall be determined by the Zoning Enforcement Officer, based on the proposed location of the detached accessory dwelling unit and its proximity to the neighboring properties.”

Prohibited Structures

In Norwalk, the following structures are prohibited and shall not be used as an accessory dwelling unit:

  • Mobile homes
  • Recreational vehicles
  • Travel trailers
  • Shipping containers
  • Storage containers
  • Any other wheeled or transportable structures

Procedure for Approval

A certificate in the form of an affidavit which verifies that the owner continues to reside on the premises, the minimum rental duration and all other conditions met at the time of the original application remain unchanged, shall be submitted to the Zoning Enforcement Officer by January 31 of each year. Applications for attached accessory dwelling units shall be permitted subject to approval by the Zoning Enforcement Officer, and applications for detached accessory dwelling units shall be permitted by the Planning and Zoning Commission, subject to Section 118-1451 with a site plan review. 

Both forms of approval are considered as-of-right which comply with the standards established by Public Act 21-29.

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