Detached, attached, garage-based and interior units have different site and design requirements. Compare privacy, costs, applicable rules and intended use before choosing a format.
A detached ADU provides physical separation from the main house and needs space for the building, foundation, utilities and access. Attached or interior units use the existing building differently. Compare site constraints, occupant needs and full project costs; no format guarantees stronger rental returns.
There is no universally right format. This guide compares common approaches; CT ADU is a Fairfield County–based design/build team for backyard ADUs, working mainly with modular factory partners and building on site when that fits better.
Most Connecticut ADUs fall into one of four types. Each changes your privacy, cost, and how much of the yard you keep.
Beyond preference, your lot and town often make the decision for you. Detached units are the most sensitive to setbacks, coverage, and delivery access; attached and interior units lean on the existing structure.
CT ADU's preliminary review focuses on detached ADU site constraints and design options. Compare the model collection and our Connecticut eligibility guide. Final design and approvals require further review.
Tell CT ADU about your property and goals for a detached ADU. We can begin identifying site and design questions before you invest in final plans.
This guide is general information, not legal advice. Whether a detached, attached, or interior ADU is permitted depends on your Connecticut town and lot — confirm current requirements with your local planning and zoning department.
Common questions about ADU formats.
Neither is universally better. A detached ADU gives you a separate entrance and no shared walls. Attached or interior units can suit tighter lots; factory-built homes also need suitable delivery access. CT ADU designs and builds detached ADUs, and we'll flag early when another approach may fit your lot better.
A detached ADU may be possible if the proposal meets applicable state and local requirements. Confirm the permitted form, placement, size and approval route for the property before designing.
A garage conversion may be possible if it meets applicable zoning, structural, fire-separation, egress and other code requirements. Existing space is not automatically suitable for habitation. CT ADU's current design/build offering focuses on detached new-construction ADUs.
Rental performance depends on location, size, condition, privacy, permitted use and current demand. Compare evidence from similar rentals and all project and operating costs. No format is universally best for rental income.
Not always. Some detached ADUs share water, sewer, and electrical with the main home; others run separate connections or meters. Your site, town, and sewer-vs-septic status determine the approach.
