Compare ADU zoning rules across 3 North Carolina cities. Average ADU score: 8.0/10.
Gathered from the 3 cities below, with the bill or ordinance each one names. Statewide measures are listed once with the cities they reached, rather than repeated for each.
Statewide law sets a floor; the numbers that decide your project are local. Here is the spread across the 3 North Carolina cities covered here, taken from each city's own ordinance rather than a state summary.
| Question | Across North Carolina |
|---|---|
| Are ADUs permitted? | 3 of 3 permit them. |
| Detached size cap | Median 840 sq ft, from 600 to 1,000 sq ft across the 3 cities publishing a numeric cap. |
| Owner-occupancy | Required in none of them. |
| Build cost | $115,000 to $400,000 depending on city and unit type. |
| Easiest and hardest here | Charlotte scores 8/10; Raleigh scores 8/10. |
Recomputed whenever a city page changes, so this and the city pages below cannot disagree.
| City | Max Size | Setbacks | Permit Fees | Build Cost | 1BR Rent | Score |
|---|---|---|---|---|---|---|
| Charlotte | 600 heated sq ft or 70% of the total floor area of the principal residence, whichever is greater, with an absolute cap of 1,000 heated sq ft for an ADU in an accessory structure (UDO 15.6.F.6.a). Example: a 1,200 sq ft house allows an 840 sq ft ADU; any house of 1,429 sq ft or more allows the full 1,000 sq ft. ADUs do not count toward the rule that all other accessory structures together may not exceed the heated first-floor area of the house (UDO 17.1.F). | 3 ft minimum from the rear lot line for an accessory structure in the established rear setback; 15 ft if the structure is 24 ft or taller (UDO 17.1.E.2). The principal-building rear setback (40 ft N1-A, 35 ft N1-B, 30 ft N1-C, 25 ft N1-D, 20 ft N1-E/F, Table 4-2) does not apply to the ADU. Keep 5 ft between the ADU and the house (17.1.E.3). | $900-$1,700 county building permit for a $100,000-$250,000 ADU (LUESA Fee Ordinance rev. July 1, 2026, Sec. II.A.1: $632.57 + $5.49 per $1,000 over $50,000, $907.12 + $5.93 per $1,000 over $100,000, $1,203.52 + $4.59 per $1,000 over $150,000) plus a $3 technology charge and the city LDIRL fee. | $115,000-$230,000 | $1,350-$1,650/mo | 8/10 |
| Durham | 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). | 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). | 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). | $150,000-$400,000 | $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) | 8/10 |
| Raleigh | 800 sq ft gross floor area on lots under 40,000 sq ft; 1,000 sq ft on lots over 40,000 sq ft (Sec. 2.6.3.G), and always less than the principal dwelling's GFA (D.1). GFA counts all conditioned space plus any attached unconditioned space; a manufactured-home ADU is capped at 600 sq ft (D.6). | 5 ft from the rear lot line on lots under 40,000 sq ft; 10 ft on lots over 40,000 sq ft (Sec. 2.6.3.H4). From an alley: 4 ft without parking, 20 ft with parking (H5). Mixed-use districts: 5 ft (Sec. 3.6.2.H4). | About $950-$1,600 in building, trade and plan-review fees for a 600-1,000 sq ft ADU under the FY2027 Development Fee Guide (building permit = 0.38% of ICC-based construction value; trades and plan review are percentages of it). Facility and utility fees are extra. | $150,000-$400,000 | $1,400-$1,880/mo | 8/10 |
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