Raleigh Zoning Districts Permitting Accessory Dwelling Units and Two-Unit Living
In the City of Raleigh, Accessory Dwelling Units (ADUs) are permitted in all Residential Districts (R-1, R-2, R-4, R-6, and R-10) and several Mixed Use Districts (RX, OX, NX, and CX). Two-unit living, which includes duplexes and two principal units on one lot, is permitted by right in most of these same districts, with specific limitations in the Residential-1 (R-1) District and expanded allowances in designated Frequent Transit Areas [Section 2.6.3.F, Section 3.6.2.F, Section 6.1.4].
Zoning Districts Permitting Second Units
The Raleigh Unified Development Ordinance classifies "second units" into two primary categories: Two-Unit Living (two principal units, such as a duplex) and Accessory Dwelling Units (a smaller, self-contained unit secondary to a principal residence).
Two-Unit Living Permissions
The following table outlines where the City of Raleigh permits two principal dwelling units on a single lot.
| District Type | Zoning District | Permission Level | Specific Use Standards |
|---|---|---|---|
| Residential | Residential-1 (R-1) | Limited (L) | Only permitted with Tiny House building type [Sec. 6.2.1.C.2] |
| Residential | R-2, R-4, R-6, R-10 | Permitted (P) | Allowed by right [Sec. 6.1.4] |
| Mixed Use | RX, OX, NX, CX, DX | Permitted (P) | Allowed by right [Sec. 6.1.4] |
Accessory Dwelling Unit (ADU) Permissions
The Raleigh Unified Development Ordinance allows ADUs in the following districts as a supplemental housing pattern [Section 2.6.3.F, Section 3.6.2.F].
| Category | Permitted Zoning Districts |
|---|---|
| Residential Districts | R-1, R-2, R-4, R-6, R-10 |
| Mixed Use Districts | RX-, OX-, NX-, CX- |
Accessory Dwelling Unit Regulations
The City of Raleigh defines an ADU as a self-contained dwelling unit located on the same lot as a principal dwelling. ADUs may be detached, attached, or internal to the principal structure [Section 2.6.3.C].
General Development Standards
- Quantity: Generally, no more than one ADU is permitted per lot. However, in a Frequent Transit Area, up to two ADUs are allowed (though only one may be attached to the principal dwelling). For townhouse developments, only one ADU is permitted per townhouse lot [Section 2.6.3.D.2].
- Prohibitions: ADUs are expressly prohibited on Flag Lots [Section 2.6.3.D.9].
- Ownership: Ownership of an ADU cannot be transferred separately from the principal dwelling unit [Section 2.6.3.D.4].
- Size: The gross floor area of the ADU must be less than the gross floor area of the total principal dwelling [Section 2.6.3.D.1.a].
ADU Size and Height Limits
The maximum size and height for an ADU in the City of Raleigh depend on the size of the lot.
| Lot Size | Max Gross Floor Area (GFA) | Max Height |
|---|---|---|
| Greater than 40,000 sf | 1,000 sf | 26' |
| 10,000 sf to 40,000 sf | 800 sf | 26' |
| Less than 10,000 sf | 800 sf | 26' |
[Section 2.6.3.G, Section 2.6.3.I, Section 3.6.2.G, Section 3.6.2.I]
Setbacks for Detached ADUs in Residential Districts
Detached ADUs must adhere to the following minimum setbacks based on the underlying Residential District lot size [Section 2.6.3.H].
| Requirement | Lot Area > 40k sf | Lot Area 10k-40k sf | Lot Area < 10k sf |
|---|---|---|---|
| Primary Street | At or behind front wall | At or behind front wall | At or behind front wall |
| Side Street | 20' | 20' | 10' |
| Side Lot Line | 10' | 5' | 5' |
| Rear Lot Line | 10' | 5' | 5' |
| From Alley | 4' (no pkg) / 20' (w/ pkg) | 4' (no pkg) / 20' (w/ pkg) | 4' (no pkg) / 20' (w/ pkg) |
Frequent Transit Development Option
The City of Raleigh provides a "Frequent Transit Development Option" to encourage higher density near transit lines. In these areas, the Raleigh Unified Development Ordinance allows for reduced lot dimensions and modified density standards to facilitate "Two-unit living" and "Multi-unit living" [Section 2.7.1, Section 3.7.1].
- R-4 District: Minimum lot area for two-unit living is reduced to 2,500 square feet [Section 2.7.1.C].
- R-6 District: Minimum lot area for two-unit living is reduced to 1,500 square feet [Section 2.7.1.C].
- R-10 District: Minimum lot area for two-unit living is reduced to 1,000 square feet [Section 2.7.1.C].
Sections Cited
- Article 2.6. Additional Housing Patterns
- Article 2.7. Frequent Transit Development Option (Residential)
- Article 3.6. Additional Housing Patterns
- Article 3.7. Frequent Transit Development Option (Mixed Use)
- Section 6.1.4. Allowed Principal Use Table
- Section 6.2.1. Household Living
- Section 12.2. Defined Terms