Everything homeowners need to know about building an accessory dwelling unit in Durham - size limits, setbacks, permits, and nearly two decades of steady ordinance reform that make Durham one of the more ADU-friendly cities in the Southeast.
Last verified: September 2026
8/10 · Very ADU-friendly
1,200 sq ft*
Max ADU size
32 ft*
Max height
Not required
Owner-occupancy
By-right
Permit type
This page summarizes Durham's Unified Development Ordinance, Sec. 5.4.2 (Accessory Uses and Structures), plus North Carolina's statewide ADU law, for general reference - it is not legal advice. Regulations change; always confirm current requirements with Durham's Development Services Center before designing or applying for permits. See sources below.
Zoning & size requirements
What you're allowed to build
ADU type
Max size
Max height
Notes
Detached (new build or garage conversion)
1,200 sq ft total heated floor area (1,000 sq ft if a single story); must stay clearly subordinate in size to the primary dwelling
The greater of 2 stories/32 ft, or the height of the primary structure; lower limits (15-25 ft) apply if the ADU sits close to a property line
Must sit behind the rear building line of the primary dwelling
Same 1,200 sq ft cap, subordinate to the primary dwelling
Must meet the same yard requirements as the primary structure
Common approach for basement or above-garage conversions
Allowed zoning districts
Most residential zoning districts, including Residential Urban (RU) and Residential Compact (RC), on lots that currently have one dwelling unit. Lots in the RR (Rural Residential) district of 4+ acres can build an ADU up to 50% of the primary dwelling's floor area instead of the flat cap. Durham's 2023 reforms also allow an ADU on a duplex lot, making it one of the first cities in the country to permit that combination. Confirm your parcel's zoning district with the Development Services Center.
Additional standards
Setbacks, parking & other rules
Setbacks
5 ft from side and rear property lines in most districts; 3 ft in the RU and RC districts
Parking
No off-street parking required for the ADU, per a 2017 text amendment
Units per lot
1 ADU per lot, including duplex lots since the 2023 reforms
Owner-occupancy
Not required. Durham dropped its own owner-occupancy requirement in 2012 after the city attorney found it conflicted with North Carolina case law; the state's 2023 ADU law now bars it outright statewide
Flood zones
ADUs are not permitted in a Special Flood Hazard Area or Future Conditions Flood Hazard Area
Building code
Must meet North Carolina Residential Code dwelling-unit standards
Ordinance history
How Durham's ADU rules got here
2006ADUs made by-right. Durham's newly adopted Unified Development Ordinance allowed ADUs without a Special Use Permit for the first time, but required the owner to live in either the primary home or the ADU.
2012Owner-occupancy requirement dropped. The city attorney advised that the mandate conflicted with state law under a North Carolina Court of Appeals ruling (City of Wilmington v. Broadus E. Hill, III), and Council removed it by text amendment.
2017Parking requirement removed. A text amendment eliminated the off-street parking requirement for ADUs.
2023Size cap raised, duplex ADUs allowed. Reforms raised the maximum size to 1,200 sq ft and allowed an ADU on a duplex lot, following adoption of Durham's new Comprehensive Plan that October.
2026Broader "missing middle" rewrite stalls. A more sweeping rewrite of the UDO, built around a new "Residential Neighborhood" zoning concept, had its February public hearing cancelled amid legal challenges over how it would treat down-zoned properties. As of this writing, that rewrite remains paused - Durham's ADU rules are still governed by the 2023-amended UDO Sec. 5.4 described on this page.
Worth knowing: county tax records show roughly 250 detached ADUs already exist in Durham, many built before formal permit tracking began, but only about 80 have been permitted through the modern system since 2008 - a reminder that even generous zoning hasn't translated into large permitted volumes yet.
Permit process
How Durham ADU permitting works
1
Confirm lot eligibility
Check your zoning district and lot conformance through the Development Services Center (dsc.durhamnc.gov) or Durham One Call before designing.
2
Prepare your plan set
You'll need a site plan showing the ADU's location, setbacks, and footprint, plus a floor plan confirming the size stays subordinate to the primary dwelling.
3
Submit your building permit application
File through the Development Services Center. A typical new dwelling up to 1,200 sq ft carries roughly a $146 building permit fee plus a $146 plan review fee (the review fee is credited back at issuance).
4
Plan review
Review generally takes 5 to 20 business days depending on project type and completeness.
5
Utility connections
Budget separately for water and sewer extension if the ADU is detached - city planning estimates put this at $8,000 or more depending on excavation and distance from the street connection.
6
Build & inspect
Pull trade permits for electrical, plumbing, and mechanical work, then schedule inspections through to final Certificate of Occupancy.
No special use permit is required for a single ADU on a residential lot. Fees and timelines are approximate - confirm current figures with the Development Services Center.
Budgeting
What it costs to build an ADU in Durham
Garage conversion
Roughly $55,000-$150,000, the least expensive path since the shell already exists
Basement conversion
Roughly $85,000-$190,000, depending on existing ceiling height and utility access
New detached ADU
Roughly $120,000-$280,000+ for a code-compliant, freestanding unit up to the 1,200 sq ft cap
Water/sewer extension (detached units)
At least $8,000 in many cases, per city planning estimates, largely independent of the ADU's size
Building permit & plan review
Roughly $146 + $146 for a new dwelling up to 1,200 sq ft (plan review fee credited at issuance)
These are general ranges from local contractor estimates and regional reporting, not quotes - actual cost depends heavily on lot conditions, finishes, and utility access. Durham's building market runs somewhat more affordable than Asheville's tourism-driven construction sector.
Before you apply
Tips for a smooth approval
Confirm your lot isn't nonconforming. Durham requires the lot to meet minimum area requirements for its district before an ADU is eligible - a quick zoning check avoids redesigning later.
Budget for the utility connection separately. Extending water and sewer to a detached ADU can run $8,000 or more before construction even starts - get that number from a contractor early.
Check flood hazard maps before you design. ADUs are barred from Special Flood Hazard Areas, so verify your parcel isn't affected before committing to a site plan.
Watch the height limit near property lines. A detached ADU close to a side or rear line faces a lower height cap (as low as 15 ft in some districts) than one set further back.
Don't assume the stalled UDO rewrite changes anything yet. Durham's broader zoning rewrite is paused pending legal review - the rules on this page are what currently applies.
FAQ
Common questions
Do I need to live on the property to build an ADU in Durham?
No. Durham dropped its own owner-occupancy requirement in 2012, and North Carolina's statewide ADU law now bars any NC city from requiring it.
Does North Carolina have a statewide ADU law?
Yes. House Bill 409 (effective October 1, 2023) requires every North Carolina local government to allow at least one ADU per single-family lot and bars owner-occupancy mandates, conditional-use zoning, and parking minimums. A second law, the Regulatory Reform Act of 2026 (signed August 11, 2026, taking effect October 1, 2026), adds further protections in cities over 50,000 residents, such as Durham, including barring ADU size caps below 800 sq ft.
How many ADUs can I build on one lot?
One ADU per lot. Since Durham's 2023 reforms, this now includes lots that already have a duplex, one of the first such allowances in the country.
Do I need extra parking for an ADU?
No. Durham removed the off-street parking requirement for ADUs in 2017.
What's the maximum size for an ADU in Durham?
1,200 sq ft of total heated floor area (1,000 sq ft if built as a single story), and it must remain clearly subordinate in size to the primary dwelling. Lots of 4+ acres in the RR district can go up to 50% of the primary dwelling's floor area instead.
Is Durham rewriting its zoning code?
A broader rewrite built around new "missing middle" zoning categories has been in development since Durham adopted a new Comprehensive Plan in 2023, but the public hearing on the draft ordinance was cancelled in early 2026 amid legal challenges, and the process remains paused. The rules on this page reflect the current, 2023-amended UDO, not the stalled rewrite.
How much does an ADU cost to build in Durham?
Garage conversions tend to run roughly $55,000-$150,000, basement conversions $85,000-$190,000, and new detached units $120,000-$280,000 or more, based on local contractor estimates and regional reporting - not counting the water/sewer extension that detached units often need.
How many ADUs has Durham actually permitted?
City planning data put the figure at roughly 80 ADUs permitted since 2008, even though county tax records show closer to 250 detached ADUs exist citywide - many built or grandfathered before permit tracking was consistent.
Can I rent my ADU out on Airbnb or a short-term rental platform?
Durham's ADU ordinance doesn't itself ban short-term rentals, but short-term rentals are regulated separately under the city's own STR rules. Confirm current short-term rental requirements with the city before finalizing your plans.
