Several Triangle towns let you build a backyard cottage. Here’s what they allow.

Anna Johnson, Tammy Grubb, Mary Helen Moore
·4 min read

State lawmakers are considering passing a law allowing backyard cottages or “granny flats,” but several Triangle communities already allow them.

The smaller, standalone structures, formally referred to as accessory dwelling units (ADUs), can be used as extra space for family members or guests to stay, or can be rented out for additional income.

House Bill 409 would allow smaller housing units to be built across the state in areas zoned for single-family homes, with some restrictions.

Here’s what is allowed in the Triangle.

Raleigh

ADUs have had a controversial history in the city, though they are now allowed now without making a zoning change.

Many units were built throughout the city but were made illegal to build through the zoning laws enacted in the 1970s. In 2019, the Raleigh City Council voted to allow ADUs through a process that required residents to apply for a special zoning district as long as a majority of nearby neighbors were supportive.

Then in 2020, the City Council voted to change the rules again by allowing them by-right. The ADUs are part of the city’s controversial plans to increase and create denser and different types of housing. The city has now launched plans to make it easier and more affordable to build the backyard cottages.

“We have spent a lot of time and energy crafting a thoughtful ADU policy — and finding creative ways to incentivize their development,” said Raleigh Mayor Mary Ann Baldwin of the state bill. “I would prefer to see our policy stay in place or even be used as a guide for statewide rules.”

There have been 164 ADU applications in Raleigh with 48 already constructed since 2020.

Durham

Durham allows residential property owners to build ADUs.

”They are allowed. They have some limitations about when they are allowed, like in particular, they need to be on a residential lot that already has another house on it,” Durham Planning Commission Chair Austin Amandolia said.

In 2019, the city council passed new building regulations called Expanded Housing Choices that make ADUs easier to build. The planning department granted 407 permits under EHC in the first three years.

Orange County

A rule change approved earlier this year allows homeowners in Orange County’s unincorporated areas to have accessory dwelling units, including mobile homes, apartments and granny flats.

The rules allow:

  • Owners who live in a home with up to 3,000 square feet of space to build an apartment or small home with up to 1,500 square feet of space.

  • Owners of larger homes to build an ADU that is half the size of their primary home.

The rules do not apply to residential land in the towns of Hillsborough, Chapel Hill or Carrboro, although all three currently allow accessory dwelling units, with limits.

Chapel Hill

Homeowners can add accessory apartments over garages and in basements, but are limited by the size of the lot and the primary home.

Most ADUs are limited to a maximum size of 750 square feet. If the accessory apartment doesn’t increase the building’s footprint, such as a basement apartment, it can be up to 75% of the size of the main home, for a maximum of 1,000 square feet.

Chapel Hill’s Town Council is poised to vote, however, on a Housing Choices plan that would allow accessory dwelling units and duplexes in all residential zoning districts.

There were some initial concerns about how specific the state bill would be regarding the size of accessory dwelling units and how far they could be built from neighboring properties, Chapel Hill Mayor Pam Hemminger said.

The town has at least 62 accessory dwelling units now and would like to add more, she said.

“Chapel Hill’s very supportive of ADUs. We already allow them, and we’re excited to increase some housing options by having these,” Hemminger said.

Carrboro

Accessory apartments are limited by the size of the lot and the primary home, with a maximum size of 750 square feet.

The new Carrboro Connects Comprehensive Plan proposes more options, including smaller lots, smaller setbacks and detached dwellings, plus a new tiny home development zoning district for smaller lots.

Staff writers Avi Bajpai and Luciana Perez Uribe Guinassi contributed to this report.