Can you build a backyard cottage or in-law suite on your Triangle lot?

In much of the Triangle, yes. Raleigh, Durham and unincorporated Wake County already allow accessory dwelling units, or ADUs: a smaller second home on the same lot as the main house, such as a backyard cottage, garage apartment or in-law suite. A new state law will require cities of 50,000 people or more to allow one ADU per single-family home for permit applications filed starting January 15, 2027. We build backyard cottages and in-law suites as well as homes, and the lot's size, zoning, covenants and septic or sewer decide what fits.

What does the new state law change?

Senate Bill 445, the Regulatory Reform Act of 2026, was signed by the governor on August 11, 2026 and became Session Law 2026-59. Its section 44 adds a new statute, G.S. 160D-917: a covered local government must allow at least one ADU that meets the NC Residential Code for each single-family detached home in residential areas where those homes are allowed. The ADU can go up at the same time as the main house or later.

The law defines an ADU as an attached or detached home on the same parcel as a single-family detached house, with less total square footage than the main house. Covered local governments may not:

• ban long-term rental of the house and the ADU to separate households
• require a conditional zoning district (a custom rezoning)
• set minimum parking requirements or other parking restrictions
• ban hooking the ADU to the main house's existing utilities, if that service has capacity for both
• charge fees above those for permitting a similar single-family home
• set a maximum ADU size below 800 square feet or above 1,000 square feet

They may still require a setback (the distance from the property line) of 10 feet or the district's general setback, whichever is less, and may require the ADU to sit to the side or rear of the house and to be smaller than it.

The law applies only to cities of 50,000 or more outside the coastal area, and it does not cover counties. It does not apply to private covenants among owners, properties in a local historic preservation district or National Historic Landmarks. Once an ADU has a construction permit, the lot can't be split to put the ADU on its own parcel. Covered cities must adopt rules by July 1, 2027.

Holly Springs Update reported the state's July 2024 population estimates as Apex 75,059 and Holly Springs 49,039, which puts Apex under the new law.

What are the rules in Raleigh, Durham and Cary today?

Raleigh. The city's ADU page says an ADU can be detached, attached or internal, above a garage or in a basement, and a new detached ADU follows the New Single-Family Dwelling permit process. Under Raleigh's zoning code, ADUs are allowed in the R-1, R-2, R-4, R-6 and R-10 districts, one per lot (up to two in a Frequent Transit Area), and not on flag lots. The cap is 1,000 square feet on lots over 40,000 square feet and 800 square feet on smaller lots, with a 26-foot height limit. A detached ADU must sit at or behind the front wall of the house, with side and rear setbacks of 5 feet on lots of 40,000 square feet or less. It needs a permanent foundation and a lockable outside entrance, and it can't be sold separately.

Durham. Durham's zoning code allows one attached or detached ADU on a residential lot, with a cap of 1,000 square feet on one story and 1,200 in total (in the RR district, on lots of four acres or more, up to 50% of the main house's floor area), always smaller than the main house. No parking is required, and ADUs are not allowed in mapped flood hazard areas. The city's Affordable ADU Pilot Program offers construction loans averaging up to about $80,000 at 2% fixed for 30 years, for owners who live in a home inside city limits with public water and sewer and agree to rent at or below 80% of area median income for 30 years. Applicants are chosen by lottery.

Cary. In 2024, Cary's Act 32 amendment proposed allowing detached ADUs in all single-unit detached districts, a size limit of 50% of the main house with an 800-square-foot cap for detached ADUs, and one parking space per ADU. The town lists Council action on April 10, 2025.

What about unincorporated Wake County?

In unincorporated Wake County, ADUs are allowed on land zoned for single-family or multifamily homes that meets development standards, and the owner doesn't have to live on the property. On septic, the county says an ADU may change the system's design flow, so more wastewater permits may be needed. The county's eligibility page says an ADU needs its own kitchen, bathroom and sleeping space, and no extra parking is required.

What decides whether a cottage fits your lot?

The same things we check on any lot: who regulates it (the county or a town), septic or public sewer, a well, the flood maps, and the slope, trees and soils. On septic, a second home may change the system's design flow, so more wastewater permits may be needed. And we handle the permits.

Your next step: decide what the cottage is for (a parent, a grown child, guests or a rental) and whether it goes up with the main house or later. Covenants can still forbid one even where the city must allow it, so have a real estate attorney read them before you count on a cottage. If you've found a cottage plan you like elsewhere, an outside plan is treated as a custom design and quoted accordingly.