Quick Answer
The 2024 North Carolina Building Codes introduce significant MEP updates for multifamily and senior living projects. Key changes include: reduced continuous kitchen exhaust from 25 CFM to 50 CFM, formal incorporation of A2L refrigerants with ASHRAE 15 compliance, expanded GFCI protection to all 120V/240V receptacles throughout dwelling units, optional mixing valves when using compliant water heaters, steeper drainage slopes (¼ inch per foot) for grease interceptor piping, and new exceptions for hub drains in equipment rooms. These updates prioritize safety, energy efficiency, and design flexibility while requiring early coordination from design teams.
As North Carolina transitions from the 2018 Building Codes to the 2024 updates, architects, engineers, and developers are asking the same question: what has changed and how will it impact our project?
At VP Engineering, we recently collaborated with our colleagues at Roland Architecture to summarize the most relevant changes in the Mechanical, Electrical, and Plumbing (MEP) codes that directly affect multifamily, senior living, and similar project types.
While this is not an exhaustive list, the following highlights provide a practical roadmap for design teams preparing to move forward under the new standards.
Mechanical Code Updates
Chapter 4 – Ventilation Rates
| Code Year | Requirement |
| 2018 | Required continuous exhaust at 25 CFM for domestic kitchens. |
| 2024 | Reduces the continuous exhaust rate to 50 CFM. Also re-establishes minimum ventilation requirements for commercial kitchens. |
Impact: The updated ventilation standards simplify coordination for residential spaces while clarifying expectations for commercial applications, supporting better energy efficiency and indoor air quality balance.
Chapter 11 – Refrigerants
| Code Year | Requirement |
| 2018 | Did not fully recognize A2L refrigerants or explicitly align with ASHRAE 15. |
| 2024 | Formally incorporates classification, installation, labeling, and clearance requirements for A2L refrigerants. Section 1101.1.1 now explicitly requires refrigerant piping to comply with both Chapter 11 and ASHRAE 15. |
Impact: These updates strengthen safety and align state code with national standards, allowing greater flexibility through recognized exceptions and alternate compliance pathways.
Electrical Code Updates
The 2024 North Carolina Electrical Code, based on the 2023 National Electrical Code (NEC), introduces several updates focused on occupant safety and system reliability.
| Code Year | Requirement |
| 2018 | Limited GFCI protection to kitchens, bathrooms, and certain receptacles. |
| 2024 | Expands GFCI protection to all 120-volt and 240-volt receptacles throughout dwelling units, including basements, laundry areas, garages, accessory buildings, and outdoor locations (even those serving HVAC systems). Also adds requirements for surge protection and outdoor service disconnects. |
Impact: These expanded protection measures significantly reduce the risk of electric shock and property damage, particularly in moisture-prone and exterior environments.
Plumbing Code Updates
Section 607.1.1 – Water Temperature Control
| Code Year | Requirement |
| 2018 | Required mixing valves at all public handwashing sinks. |
| 2024 | Allows water heaters with ASSE 1082/1084-compliant thermostat controls to serve as temperature-limiting devices, making mixing valves optional rather than mandatory. |
Impact: Provides design flexibility and potential cost savings by allowing compliant water heaters to perform temperature control without additional mixing valve installation. This is particularly beneficial for senior living facilities where centralized hot water systems are common.
Section 704.1 – Drainage Piping Slope
| Code Year | Requirement |
| 2018 | Stated that horizontal drainage piping shall be installed and sloped not less than that indicated in Table 704.1. |
| 2024 | Retains this requirement but adds that “where the drainage piping is upstream of a grease interceptor, the slope of the piping shall be not less than ¼ inch per foot.” |
Impact: Standard slope for horizontal drainage piping is 1/8 inch per foot, but this new requirement effectively doubles the slope for piping discharging into grease interceptors (common in commercial kitchens, trash rooms, and similar spaces). Designers should account for the resulting deeper inverts and elevation impacts where grease interceptors are used. Downstream piping may maintain the 1/8-inch-per-foot minimum (for 3-inch or larger drains).
Section 802.3/802.4 – Waste Receptors
| Code Year | Requirement |
| 2018 | Prohibited waste receptors in return air plenums, requiring physical separation between air-handling units (AHUs) and hub drains located in mechanical closets. |
| 2024 | Adds an exception allowing hub drains in dwelling-unit equipment rooms and furnace rooms. |
Impact: Reduces spatial and coordination constraints in multifamily and residential mechanical room layouts, simplifying design and installation.
Section 1104.2 – Floor Drains and Waste Receptors
| Code Year | Requirement |
| 2018 | Prohibited floor drains from connecting to storm drains. |
| 2024 | Expands this language to include “waste receptors,” while creating an exception for open and enclosed parking garages. |
Impact: Provides flexibility by allowing certain floor drains—such as elevator sump pump discharges—to connect to either sanitary or storm systems. This can reduce the need for extended sanitary runs and lower construction costs in parking garage designs.
Why These Changes Matter
For architects and engineers, the 2024 code cycle brings both challenges and opportunities. Reduced ventilation rates, expanded safety measures, and added flexibility in plumbing design all require close coordination early in the design process.
At VP Engineering, we are committed to guiding our clients through these updates so that projects remain compliant, efficient, and cost-effective without sacrificing safety or performance. Our expertise in multifamily and senior living design ensures your project benefits from these code changes while meeting all regulatory requirements.
The transition to the 2024 NC Building Codes is more than a checklist of new requirements; it’s an opportunity to deliver smarter, safer, and more resilient buildings.
Frequently Asked Questions
When did the 2024 North Carolina Building Codes become effective?
The 2024 North Carolina Building Codes officially went into effect, replacing the 2018 codes. All new projects must comply with the updated mechanical, electrical, and plumbing code requirements. Design teams should review these changes early in the design process to ensure full compliance and avoid costly revisions during construction.
How do the expanded GFCI requirements affect existing multifamily projects?
The expanded GFCI protection requirements apply to all 120-volt and 240-volt receptacles in new construction and substantial renovations. Existing buildings are typically grandfathered under previous codes unless significant electrical work triggers code compliance upgrades. For multifamily projects, this means added upfront costs but significantly improved safety for residents, particularly in moisture-prone areas like basements, laundry rooms, and outdoor spaces.
What should I know about A2L refrigerants in the 2024 code?
The 2024 code formally recognizes A2L refrigerants (mildly flammable refrigerants) and requires compliance with ASHRAE 15 standards for installation, labeling, and clearances. A2L refrigerants, such as R-32 and R-454B, are increasingly common in modern HVAC systems due to their lower global warming potential. The code update provides clear guidelines for safe installation while allowing design flexibility through recognized exceptions. MEP engineers should coordinate refrigerant system design early to ensure compliance with both Chapter 11 and ASHRAE 15 requirements.
