Designing an Auxiliary Dwelling Unit (ADU)
AKA: a “Mother-in-Law Suite”
An ADU, or Auxiliary Dwelling Unit is a small self-contained apartment either attached, or in some cases detached from an existing house. It is sometimes referred to as a “Mother-in-Law Suite”. The ADU is an increasingly popular architectural solution to multiple problems, economic and social, enabling older family members to live close to, but still independent of their children. This saves the family considerable money over time, and enhances the quality of life for all. The grandchildren have been shown to benefit greatly from this arrangement. It can be a wonderful architectural solution. But the regulations governing ADU’s in Connecticut can be complex and must be carefully considered by an experienced architect to ensure that it will be permitted by the land use/building department in your town or City.
Although the State of Connecticut has mandated acceptance of ADU’s for any town which has not explicitly opted out of this requirement, every town and city in Connecticut has its own policy toward ADU’s, and the requirements and constraints can vary greatly from one town to the next. All jurisdictions in Connecticut set forth the rules and constraints for ADU’s in their zoning regulations, so your architect will begin your project by researching the zoning regulations in your jurisdiction. The architect will be checking for:
1. Any minimum lot size requirements for an ADU, and the size of the ADU relative to the size of the existing house. A few Examples:
a. ADU’s in the Town of Naugatuck,CT and East Lyme are quite limited on smaller lots. Lots under 9000 sq ft in Naugatuck cannot have a second kitchen. Larger lots in Niantic and East Lyme have more liberal requirements for ADU’s. Creative architectural solutions are sometimes required to meet the regulations.
b. Mystic CT permits ADU’s up to a maximum of 1,000 square feet. Auxiliary Dwelling Units in Mystic cannot exceed 50% of the size of the existing house.
c. Glastonbury CT permits ADU’s up to 800 sq. ft. Auxiliary ADU’s in Glastonbury may not exceed 30% of the size of the existing house.
d. New Haven is very friendly to Auxiliary Dwelling Units. ADU’s in New Haven are permitted up to 1200 sq ft/100% of the size of the existing house.
e. Some towns, like Old Saybrook, have both a minimum and a maximum size for ADU’s. An Auxiliary Dwelling Unit in Old Saybrook must be between 500 sq. ft. and 1000 sq. ft, and may not exceed 30% of the size of the existing house.
Once your architect has determined the constraints, he will meet you on-site for the initial design meeting. It’s important to have all of the family members present for that meeting, so that your architect gets the chance to learn as much as possible about how every family member lives and interacts.
Your architect will perform a measure-up of your existing house. He will then develop an accurate “as-built” model of your existing house in three dimensions. Most architects now use 3D CAD programs, such as Revit, which enable you to see the house as a 3D model. A 3D model is very helpful in visualizing the finished house!
Once the as-built model has been completed, your architect will design the Schematic Drawings. These consist of floor plans, elevations, a conceptual building section, and a 3D model of the house when the addition is complete.
Your architect will meet with you to review the Schematic Drawings. He or she will be listening carefully to your reactions to the schematics and will make any adjustments or revisions needed.
Once you’re satisfied with the schematics, your architect will develop the full Construction Drawings needed for a building permit and bidding. These plans will be detailed and complete. They will become the basic contract document defining the builder’s scope of work. (see my other blogs on the bidding process).
If designed by an experienced professional architect, an Auxiliary Dwelling Unit is a wonderful solution which can provide a family with deep value over time. Good luck with your architectural project!
Roger Greenwald, AIA
Architect
Note: To obtain a building permit for an ADU in Connecticut, you will need a survey of the property showing the existing house in relation to the lot lines. Be sure to check your settlement folder or ask the real estate lawyer who settled your purchase of the house. If a survey does not exist, you’ll want to have the architect help you get that process started using a licensed surveyor or civil engineer.