Durham allows one accessory dwelling unit by right on any residential lot that has one or two primary dwellings, attached or detached, under Unified Development Ordinance Sec. 5.4.2 (as amended through June 2026). Heated floor area is capped at 1,000 sq ft on a single storey or 1,200 sq ft total over two storeys, the unit must stay smaller than the main house, and on RR-zoned lots of 4 acres or more the cap is 50% of the house instead. A detached unit sits behind the front wall of the house at least 5 ft from side and rear lot lines (3 ft in the RU and RC districts) and may rise to 2 storeys or 32 ft; no parking and no owner-occupancy are required. Approval is a building permit through Durham City-County Building & Safety, submitted digitally through Dplans, with about $1,300 in City permit and review fees for a new detached unit before any impact fee or utility connection charge.
Zoning & Size Requirements [1][2][3][4][5]
Yes — Durham allows ADUs. A detached ADU can typically be up to 1,000 sq ft under current North Carolina and Durham zoning rules.
See what this means for your lot — ask Durham ADU builders for a quote →
| Allowed Zones | All residential districts (RR, RS-20, RS-10, RS-8, RS-M, RU-5, RU-5(2), RU-M, RC) and any other district where household living is a permitted use: an ADU is an accessory use to Household Living (UDO Sec. 5.2.3) on a lot developed with one or two primary dwelling units (Sec. 5.4.2.B.1.a). Not permitted in Special Flood Hazard Areas or Future Conditions Flood Hazard Areas (Sec. 5.4.2.A). |
| Max Size (Detached) | 1,000 sq ft of heated floor area on a single storey, or 1,200 sq ft total across two storeys (UDO Sec. 5.4.2.B.4), and in every case less than the floor area of the primary house. RR District lots of 4 acres or more use a different cap: 50% of the house's heated floor area. On a single-family lot the detached accessory structure may be built as a two-unit duplex ADU as long as both units total no more than 1,200 sq ft (Sec. 5.4.2.B.1.d). |
| Max Size (Attached) | Same caps as detached: 1,000 sq ft on one storey, 1,200 sq ft total, and never equal to or larger than the primary structure (Sec. 5.4.2.B.4). A conversion of existing space inside the house is exempt from height limits (Sec. 5.4.2.B.7.c). |
| Max Size (JADU) | No junior-ADU category in the Durham UDO. An internal conversion (basement, attic, attached garage) is simply an attached ADU under the same 1,000 / 1,200 sq ft caps. |
| Max Height | Detached: the accessory-structure limit, the greater of 2 storeys and 32 ft or the height of the primary house (Sec. 5.4.1.C); in Design Districts the lesser of 3 storeys or 40 ft and never taller than the house (Sec. 5.4.1.E). An attached addition follows the district limit for the house, 3 storeys / 40 ft in the RS and RU-5 districts (Secs. 6.3.1, 6.4.1). Interior conversions have no height test (Sec. 5.4.2.B.7.c). |
| Max Units | One ADU per lot, on lots with one or two primary dwelling units (Sec. 5.4.2.B.1.a). On a single-family lot that one accessory structure may contain two units (a duplex ADU) within 1,200 sq ft combined (Sec. 5.4.2.B.1.d). Places of worship and other civic uses have separate allowances (Sec. 5.4.2.B.1.b). |
Setback Requirements [1][2][3][4][5]
Durham requires a rear setback of about 5 ft for a detached ADU, and no additional parking is required. Owner-occupancy is not required — you can rent it out without living on the property.
| Rear Setback | 5 ft for a detached ADU in most residential districts; 3 ft in the RU and RC districts (UDO Sec. 5.4.1.B.1.a-b). An attached ADU (addition) must meet the house's rear yard, which is 25 ft in every RS, RU and RC district (Sec. 7.1.2). |
| Side Setback | 5 ft for a detached ADU; 3 ft in the RU and RC districts (Sec. 5.4.1.B.1.a-b). An addition follows the district side yard for the house: 12 ft in RS-20, 10 ft in RS-10, 9 ft in RS-8, 5 ft in RS-M, RU-5, RU-M and RC (Sec. 7.1.2). |
| Front Setback | A detached ADU must sit behind the front building line of the house (Sec. 5.4.1.B.1); beside the house is fine as long as it does not project past the front facade. On corner lots one of the two street yards may use the side-yard standard (Sec. 5.4.1.B.5); on flag lots the unit may be in front of the house (Sec. 5.4.1.B.6); RR lots of 2 acres or more may place it in front of the house outside the street yard (Sec. 5.4.1.B.1.c). |
| Parking Required | None: 'No parking is required for an accessory dwelling' (UDO Sec. 5.4.2.B.6; the ADU parking requirement was removed by a 2017 text amendment). The house keeps its own 2-space minimum under Sec. 10.3.1, which a driveway satisfies (Sec. 10.2.3). |
| Owner Occupancy | Not required. The 2006 UDO's owner-occupancy condition was removed by text amendment after a 2012 City Attorney opinion that it conflicted with state law (NC Court of Appeals, City of Wilmington v. Hill); Sec. 5.4.2 contains no occupancy, deed-restriction or rental condition. |
| Min Lot Size | No minimum lot size in Sec. 5.4.2 and density limits do not apply to ADUs (Sec. 5.4.2.B.1.c). The only lot-size trigger is the RR District, where 4 acres or more switches the size cap to 50% of the house. A legal nonconforming lot at least 30 ft wide may still be developed with a house under Sec. 14.3.2. |
Permit Process & Fees [6][7][8][9][10][11][12][13]
An ADU permit in Durham goes through a standard permit review. No turnaround time is published. The plan-review fee is paid at submittal and status is tracked in Dplans / LDO; the first re-review is free, the second costs $200; an application with no activity for six months is voided and the plan-review fee is forfeited. Permit fees: Building & Safety schedule (effective 7/1/2018, still the posted schedule): new dwelling up to 1,200 sq ft $146 building permit + $146 plan review; electrical 100-200 amp service $156; mechanical heating/cooling system $125; plumbing for a new dwelling $170; Homeowner's Recovery Fund $10. Plus Planning review of the building permit $110 and Infrastructure Residential Building Permit Review $436.80 (Development Services fee menu, July 2026). About $1,300 in City fees for a new detached unit; a conversion or addition is priced as a residential addition/renovation ($125-$250 permit + $125 plan review, plus trade permits).
| Approval Process | Building permit only; no planning application, public hearing or site plan for a code-compliant ADU on a residential lot. Submit building plans digitally through Dplans to Durham City-County Building & Safety (919-560-4144) with a signed application, the residential checklist and a plot plan sealed by an NC surveyor; Planning review ($110) and Public Works Infrastructure review ($436.80) run inside the same building-permit case in the Land Development Office (LDO) system, where the electrical, mechanical and plumbing permits are also applied for. In a local historic district a Certificate of Appropriateness comes first. |
| Review Timeline | No turnaround time is published. The plan-review fee is paid at submittal and status is tracked in Dplans / LDO; the first re-review is free, the second costs $200; an application with no activity for six months is voided and the plan-review fee is forfeited. |
| Permit Fees | Building & Safety schedule (effective 7/1/2018, still the posted schedule): new dwelling up to 1,200 sq ft $146 building permit + $146 plan review; electrical 100-200 amp service $156; mechanical heating/cooling system $125; plumbing for a new dwelling $170; Homeowner's Recovery Fund $10. Plus Planning review of the building permit $110 and Infrastructure Residential Building Permit Review $436.80 (Development Services fee menu, July 2026). About $1,300 in City fees for a new detached unit; a conversion or addition is priced as a residential addition/renovation ($125-$250 permit + $125 plan review, plus trade permits). |
| Impact Fees | Street impact fee per ADU: $293 Downtown, $531 North, $1,405 South (City Fee Schedule Part 4-112 tables, 2009 rates still posted by Building & Safety); ask whether the parks ($425/unit) and open-space ($222/unit) impact fees are also charged. Water and sewer capital facility fees apply to a new connection: $5,619 for a 5/8-inch meter (water $2,591 + sewer $3,028; Reference Guide for Development Sec. 13.1.E, in force since Jan 1, 2024) plus a $721 City meter set. The plot-plan checklist lets an ADU share the house's sewer service and meter, with a second meter optional for separate billing; confirm with Public Works Engineering (919-560-4326) whether any capital facility fee is assessed when no new tap is made. |
| Plan Check | Digital plan review through Dplans: drawings split by trade as flattened PDFs under 200 MB, plan-review fee credited against the permit fee at issuance, sealed plot plan required for any new or changed footprint. An optional Enhanced Plan Review (face-to-face, $600 per hour) is available after one standard review round. |
| Pre-Approved Plans | None. The City's Affordable ADU Pilot Program (Housing & Neighborhood Services with Coram Houses) offered 2% fixed 30-year construction loans of up to $80,000 to 20 homeowners who rent the unit to tenants at or below 80% of Area Median Income for 30 years; all 20 slots are filled and applications are closed. |
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Construction Costs [14][15][16][17]
Building an ADU in Durham typically costs $150,000-$400,000 ($250-$400+ per sq ft); a garage conversion runs $65,000-$140,000.
See what this means for your lot — ask Durham ADU builders for a quote →
| Average Build Cost | $150,000-$400,000 |
| Cost per Sq Ft | $250-$400+ |
| Garage Conversion | $65,000-$140,000 |
| Prefab ADU (Installed) | $80,000-$137,000 |
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Rental Income Potential [18][19][20]
A 2-bedroom ADU in Durham rents for around $1,550-$1,750/mo (Zillow $1,560; RentCafe $1,632; HUD FY2027 FMR $1,745). Durham rents were flat to slightly down year over year in 2026, an estimated Gross yield roughly 5-9% before expenses: $1,400-$1,550/mo ($17,000-$18,600 a year) on a $200,000-$300,000 build; net return is lower after property tax, insurance, vacancy and maintenance.
| Avg Rent (1 Bedroom) | $1,200-$1,550/mo (Zillow Sept 2026 average $1,195; RentCafe Aug 2026 $1,414; HUD FY2027 Fair Market Rent $1,554 for Durham-Chapel Hill) |
| Avg Rent (2 Bedroom) | $1,550-$1,750/mo (Zillow $1,560; RentCafe $1,632; HUD FY2027 FMR $1,745). Durham rents were flat to slightly down year over year in 2026 |
| Short-Term Rental | The UDO (amended through June 2026) has no short-term-rental use category and Sec. 5.4.2 puts no rental or occupancy condition on ADUs, so zoning does not bar nightly rental; verify current City Code and any HOA covenants before listing. |
| Est. Annual ROI | Gross yield roughly 5-9% before expenses: $1,400-$1,550/mo ($17,000-$18,600 a year) on a $200,000-$300,000 build; net return is lower after property tax, insurance, vacancy and maintenance |
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Recent Law Changes
What's Changed Recently
- SCAD text amendment (TC22-01, Simplifying Codes for Affordable Development), effective Jan 1, 2024 in both City and County: ADU size cap raised from 800 sq ft to 1,000 sq ft single-storey / 1,200 sq ft total; ADUs allowed on duplex lots and as a two-unit duplex accessory structure; accessory-structure height raised from 25 ft to 2 storeys / 32 ft; detached units may now sit beside the house behind the front building line instead of only behind the rear building line
- UDO last amended June 15, 2026 (City) and June 22, 2026 (County); the March 1, 2026 print edition and the live online Sec. 5.4 text are identical, so no ADU rule has changed since SCAD
- The replacement Land Development Code (the 'New UDO' drafted 2024-2026) that would have rewritten these rules was put on indefinite hold on Feb 20, 2026 after property owners threatened litigation over a down-zoning carve-out; the existing UDO stays in force with no restart date
- Water and sewer capital facility fees rose to $5,619 for a 5/8-inch meter on Jan 1, 2024 (from $3,299 under the 2018 schedule); they are charged with the application for a new service connection, so ask Public Works Engineering before deciding whether the ADU gets its own tap
- City Affordable ADU Pilot Program (2% fixed 30-year loans up to $80,000, $1.75 million from Forever Home Durham, 30-year affordability at 80% AMI) selected its 20 homeowners; applications are closed
- Planning & Development fee menu updated July 1, 2026: Planning review of a building permit $110; Infrastructure Residential Building Permit Review $436.80; Major COA for new construction in a local historic district $521
Tips for Building an ADU in Durham
- A one-storey detached unit caps at 1,000 sq ft; only a two-storey design reaches the 1,200 sq ft total, and Sec. 5.4.1.C lets it go to 2 storeys or 32 ft, so a second floor or loft is how you get the extra 200 sq ft.
- Garage conversion: a detached garage already closer than 5 ft to a lot line is a nonconforming accessory structure, and Sec. 5.4.2.B.3 lets you convert it (a minor special use permit under Sec. 14.4 may be needed depending on scope); converting an attached garage inside the house has no height test and adds no parking requirement, just keep two driveway spaces for the house.
- Decide on metering before the plot plan is drawn: the ADU may share the house's water meter and sewer service, a second meter is optional for separate billing, but a new City tap carries the $5,619 capital facility fee plus a $721 meter set.
- Check the FEMA and Future Conditions flood maps first: ADUs are prohibited outright in Special Flood Hazard Areas and Future Conditions Flood Hazard Areas (Sec. 5.4.2.A).
- In the Old West Durham Neighborhood Protection Overlay the 0.325 floor-area ratio counts the ADU's full square footage plus any garage (Sec. 4.6.6.C.1): a 7,500 sq ft lot with a 1,450 sq ft house and 400 sq ft garage has about 588 sq ft left. Local historic districts need a Certificate of Appropriateness ($521 for new construction) before the building permit.
- RR lots of 4 acres or more: the 50%-of-house rule replaces the 1,200 sq ft cap, so a 1,888 sq ft house allows a 944 sq ft ADU; on RR lots of 2 acres or more the unit may also sit in front of the house as long as it stays out of the street yard.
- Cost basis (2026-09-19 re-verification): avg build cost: $150,000-$400,000 for a 600-1,000 sq ft detached unit at the $250-$400+ per sq ft that Triangle design-build firms quote (CQC Home, Mar 2026); a Durham builder publishes $90,000-$300,000+ for 600-1,200 sq ft detached units (Radford Building Co., Mar 2026) | cost per sqft: $250-$400+ per sq ft for new detached construction in the Triangle (CQC Home, Mar 2026); NC modular ground-to-finish pricing starts around $215 per sq ft (HOUSEI, 2026) | garage conversion: $65,000-$140,000 for a full ADU with kitchen, bath and separate entrance in the Triangle (Boco Modern, Aug 2026); a Durham builder's range is $50,000-$100,000+ (Radford, Mar 2026), and a design-build attached unit runs $150,000-$300,000+ (CQC Home, Mar 2026) | prefab adu: NC prefab list prices start at $80,000-$137,000 for 325-650 sq ft models before foundation, utility connections and site work (HOUSEI, 2026); allow roughly $150,000-$220,000 delivered and connected (estimate; get a site-specific quote)
ADU Builders in Durham
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Sources & References
All data on this page is sourced from official government records and verified market data. View our full methodology.
- Unified Development Ordinance, print version updated March 1, 2026, Secs. 5.4.1-5.4.2 (pp. 249-252), 4.6.6, 6.3.1, 7.1.2, 10.2.3, 10.3.1, 14.3.2 | City of Durham Municipal Code — Accessed 2026-09-19
- Sec. 5.4 Accessory Uses and Structures | Searchable Durham UDO (last amended City June 15, 2026 / County June 22, 2026) Municipal Code — Accessed 2026-09-19
- TC2200001 Simplifying Codes for Affordable Development (SCAD), Detailed Analysis (Attachment A) | Durham City-County Planning Planning Department — Accessed 2026-09-19
- Attachment G: Accessory Dwelling Units, Background Information and Summary of Proposals (2019) | Durham City-County Planning Planning Department — Accessed 2026-09-19
- New UDO / Land Development Code: project indefinitely on hold as of Feb 20, 2026 | Engage Durham Planning Department — Accessed 2026-09-19
- Building Permit Fee Schedule (effective 7/1/2018) | Durham City-County Building & Safety Planning Department — Accessed 2026-09-19
- Electrical, Mechanical and Plumbing Permit Fee Schedules | Durham City-County Building & Safety Planning Department — Accessed 2026-09-19
- Planning & Development Fees and Payment Menu, effective July 1, 2026 (Form 34642) | City of Durham Planning Department — Accessed 2026-09-19
- Plans Review Requirements | Durham City-County Building & Safety Planning Department — Accessed 2026-09-19
- Infrastructure Review Group Building Permit Plot Plan Checklist (07-01-2026) | City of Durham Planning & Development Planning Department — Accessed 2026-09-19
- Reference Guide for Development 2026-07-01, Sec. 13.1 Water and Sanitary Sewer Charges (pp. 251-252) | City of Durham Public Works Government Data — Accessed 2026-09-19
- Fee Schedule of the City of Durham, Ordinance 15981 (rev. Aug 2, 2022), Part 4-112 Impact Fees and Part 15-103 Capital Facilities Fees | City of Durham Municipal Code — Accessed 2026-09-19
- ADU Pilot Program | City of Durham Housing & Neighborhood Services Planning Department — Accessed 2026-09-19
- How Much Does It Cost to Build an ADU in Raleigh, Durham, and the Triangle? (Mar 24, 2026) | CQC Home industry — Accessed 2026-09-19
- ADU in Durham NC: Cost, Rules & What Builders Charge (Mar 21, 2026) | Radford Building Company industry — Accessed 2026-09-19
- Garage Conversion Cost in 2026: Raleigh Triangle Guide (Aug 12, 2026) | Boco Modern industry — Accessed 2026-09-19
- Prefab ADUs & Backyard Units in North Carolina, model pricing | HOUSEI industry — Accessed 2026-09-19
- Average Rental Price in Durham, NC (updated Sept 17, 2026) | Zillow Rental Manager Market Data — Accessed 2026-09-19
- Average Rent in Durham, NC (updated Aug 31, 2026) | RentCafe Market Data — Accessed 2026-09-19
- FY 2027 Schedule of Metropolitan & Non-Metropolitan Fair Market Rents, Durham-Chapel Hill NC HMFA | HUD Government Data — Accessed 2026-09-19
- Unified Development Ordinance (UDO) landing page, last adopted update March 1, 2026 | City of Durham Planning Department — Accessed 2026-09-19
- City-County Building & Safety | City of Durham Planning Department — Accessed 2026-09-19
Frequently Asked Questions
Can I build an ADU in Durham?
Yes. ADUs are allowed in All residential districts (RR, RS-20, RS-10, RS-8, RS-M, RU-5, RU-5(2), RU-M, RC) and any other district where household living is a permitted use: an ADU is an accessory use to Household Living (UDO Sec. 5.2.3) on a lot developed with one or two primary dwelling units (Sec. 5.4.2.B.1.a). Not permitted in Special Flood Hazard Areas or Future Conditions Flood Hazard Areas (Sec. 5.4.2.A). in Durham. The maximum size for a detached ADU is 1,000 sq ft of heated floor area on a single storey, or 1,200 sq ft total across two storeys (UDO Sec. 5.4.2.B.4), and in every case less than the floor area of the primary house. RR District lots of 4 acres or more use a different cap: 50% of the house's heated floor area. On a single-family lot the detached accessory structure may be built as a two-unit duplex ADU as long as both units total no more than 1,200 sq ft (Sec. 5.4.2.B.1.d).. Owner-occupancy is not required, so you can rent out the ADU.
How much does an ADU cost in Durham?
ADU construction in Durham typically costs $150,000-$400,000. Garage conversions run $65,000-$140,000, and prefab ADUs cost $80,000-$137,000.
How much can I rent an ADU for in Durham?
Average ADU rents in Durham are $1,200-$1,550/mo (Zillow Sept 2026 average $1,195; RentCafe Aug 2026 $1,414; HUD FY2027 Fair Market Rent $1,554 for Durham-Chapel Hill) for a 1-bedroom and $1,550-$1,750/mo (Zillow $1,560; RentCafe $1,632; HUD FY2027 FMR $1,745). Durham rents were flat to slightly down year over year in 2026 for a 2-bedroom unit.
Do I need parking for an ADU in Durham?
None: 'No parking is required for an accessory dwelling' (UDO Sec. 5.4.2.B.6; the ADU parking requirement was removed by a 2017 text amendment). The house keeps its own 2-space minimum under Sec. 10.3.1, which a driveway satisfies (Sec. 10.2.3).. Check with Durham planning department for the latest North Carolina ADU parking rules, as many states have relaxed requirements in recent years.
How long does it take to get an ADU permit in Durham?
Durham does not publish a standard ADU review timeline. No turnaround time is published. The plan-review fee is paid at submittal and status is tracked in Dplans / LDO; the first re-review is free, the second costs $200; an application with no activity for six months is voided and the plan-review fee is forfeited. Permit fees: Building & Safety schedule (effective 7/1/2018, still the posted schedule): new dwelling up to 1,200 sq ft $146 building permit + $146 plan review; electrical 100-200 amp service $156; mechanical heating/cooling system $125; plumbing for a new dwelling $170; Homeowner's Recovery Fund $10. Plus Planning review of the building permit $110 and Infrastructure Residential Building Permit Review $436.80 (Development Services fee menu, July 2026). About $1,300 in City fees for a new detached unit; a conversion or addition is priced as a residential addition/renovation ($125-$250 permit + $125 plan review, plus trade permits).
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