2024 Building Code Updates

2024 International Codes

The International Code Council has published the 2024 editions of all International Codes, continuing the evolution of building standards. While adoption timelines will vary by jurisdiction, these updates reflect ongoing efforts to enhance public safety, improve energy efficiency, and reduce environmental impact. As these new codes are implemented, it is essential to understand key changes that may influence building design and construction.

As has been the trend over the past several International Code updates, the International Energy Conservation Code (IECC) has the most significant changes. As is now typical for IECC updates, there are numerous changes to enhance energy performance requirements that will have significant impacts on construction costs. The 2024 IECC prioritizes electrification as a strategy to support decarbonization efforts and incorporates mandatory renewable energy requirements for certain building types. As jurisdictions adopt these new standards, industry professionals must adapt to ensure code compliance while leveraging design strategies that minimize the impact on project budgets.

The changes noted below highlight the differences between the 2021 and 2024 versions of the International Building Code, Energy Conservation Code, Mechanical Code, Plumbing Code, and Fire Code. Jurisdictions previously utilizing the earlier versions of the codes may see more significant changes.

International Building Code (IBC)

• IBC 104 – Duties and Powers of the Code Official has been expanded and reorganized. Similar language has also been added to all other International Codes, such as IFC, IMC, and IPC. Items indicated/elaborated on include:
  • The code official shall be the one to interpret the code and determine compliance.
  • The code official can compel the owner to provide a technical report to help determine compliance with the code at no cost to the jurisdiction.
  • Criteria for seeking approval for alternative materials, design, or method of construction.
  • Record-keeping requirements for the code official.
• IBC 915 – Carbon Monoxide (CO) alarm and detection are now required for all types of occupancies and not just residential (type R) and school (type E) occupancies.
• IBC 1603 – Tornado design data and design requirements have been added to this chapter.
• IBC 1604.5.2 – Photovoltaic panel systems shall be assigned a risk category based on this section and shall meet the support requirements of the assigned risk category.
• IBC 1609.5 – Now includes provisions for structural loading of risk category III and IV buildings in tornado-prone regions.
• IBC 2902 – Additional occupancy categories have been added for minimum plumbing fixture quantities. New categories include ambulatory and outpatient care facilities as well as many additional institutional categories not previously included.
• IBC 3302 – This new section outlines requirements described as the “Owner’s Responsibility for Fire Protection,” which includes development of a site safety plan, appointment of a site safety director, and daily fire safety inspections. All of which should be submitted for approval during permitting and are enforceable by the building code official in the jurisdiction.

International Energy Conservation Code (IECC)

• C402 – Multiple enhancements have been made to the sections pertaining to air barriers, air leakage, and the building thermal envelope. The goal is to reduce air leakage through the building envelope to improve overall building performance. Locations in C402 where air leakage testing is included; these tests are indicated to be performed by an approved third party, which was not a requirement in the previous version.
• C403.4.7 – The 2021 version of the IECC introduced a new requirement for cooling and heating setpoint interlocks where operable openings to the outdoors are larger than 40 square feet. The 2024 version of the IECC has expanded these requirements to include all doors separating conditioned space from the outdoors, regardless of door size, unless the door or opening falls under one of the exceptions listed in the section. Requirements for operable openings other than doors remain similar to the 2021 version.
• C403.4.8.1 and C403.4.8.2 – Specific upper and lower relative humidity limits have been added to prevent excessive electricity or fossil fuel usage for the purposes of dehumidification and humidification. These prescribed limits do not apply to spaces that require conditions outside of the listed limitations, such as museums or deemed to be critical applications, such as healthcare facilities.
• C403.7.1 – While similar to the previous version, there is new verbiage that will require even more spaces to be provided with demand control ventilation, depending on the climate zone. For zones 5A, 6, 7, and 8, this includes spaces larger than 250 square feet with occupant density greater than 15 people per 1,000 square feet.
• C403.7.8 – Requirements for occupied standby controls have been added for certain space types listed in this section. The goal is to set back space cooling and heating setpoints, reduce supply airflow to the spaces, and reduce system ventilation airflow to lower overall energy consumption when the spaces are unoccupied.
• C403.7.9 – This new section states that the supply fan within an indoor air handling unit that provides cooling and heating to a dwelling unit cannot be used to also supply outdoor ventilation air to the dwelling unless the fan exceeds a certain efficiency threshold. This requirement is pushing toward the use of decoupled systems for space conditioning and ventilation. This design might include a dedicated outdoor air system or energy recovery ventilator to provide ventilation, while a more conventional air conditioning system would be provided for space cooling and heating.
• C403.8.6.2 – Provides a list of acceptable methods to control exhaust fans intermittently for bathrooms and toilet rooms. In addition to automatic controls, a method to provide a manual on capability shall be provided.
• C403.10 – stricter efficiency requirements necessitate the selection of high-efficiency gas boilers with a minimum thermal efficiency of 90% in new buildings; and associated HVAC heating water distribution systems are now required to have coils and other heat exchangers designed with a return water temperature of 120°F or less.
• Section C404 Service Water Heating has been revised. This section addresses minimum efficiency of and controls for water heating equipment, as well as insulation of hot water piping.
  • Table C404.2 Minimum Performance of Water-Heating Equipment has been reorganized and revised. Most notably, the “Performance Required” metric for water heating equipment has been changed from a minimum energy factor (EF) basis to a uniform energy factor (UEF) basis per the 2017 updated Department of Energy test procedures. This new approach more accurately measures energy usage under real-world conditions. It also provides consistent “apples-to-apples” standards for measuring energy efficiency performance across national equipment brands. This enables owners and specifiers to better evaluate equipment options and true operating costs.
  • Electric instantaneous water heaters are now explicitly identified as an equipment category in updated Table C404.2 and have clear minimum performance criteria identified. Previously, this was not the case.
  • Insulation requirements for service water heating piping are now captured by Table C404.4.1 as part of this Section, whereas previously this was addressed under the more general Section C403 Building Mechanical Systems. In addition, minimum insulation wall thicknesses for higher temperature water piping up to 1-1/4″ in size have been reduced slightly. Lastly, under C404.4, the list of exceptions where pipe insulation is NOT required has been revised. Most notably, pipe insulation is not required for piping in existing buildings where alterations are being made, but space or access is insufficient to meet the requirements.
  • C404.6.1 Circulation Systems has been revised. For hot water circulation systems with multiple risers or piping zones, balancing must now be achieved via self-actuating thermostatic balancing valves or another automatic means of flow control. This indicates that the use of traditional manual balancing valves, such as the Bell & Gossett “Circuit Setter” and other similar offerings is no longer allowed.

• C405.2.1 – Occupancy sensing lighting controls have been expanded to include data centers, medical supply rooms, laundry/wash areas, and telemedicine rooms.
• C405.2.3 – Dimming lighting controls now require continuous dimming from 100% to 10% or less. The previous version of the energy code included less prescriptive light-reduction controls. The are also now specific space types for which continuous dimming is required, such as classrooms, conference rooms, lobbies, offices, lounges/break rooms, gyms/fitness rooms, healthcare imaging and exam rooms, etc.
• C405.2.4 – Daylight responsive controls are now required for spaces where lighting power exceeds 75 Watts in a single zone or 150 Watts combined, reduced from 150W / 300W in the 2021 version of the code.
• C405.2.8.1 – Performance requirements for demand-responsive lighting controls are now required to automatically reduce controlled lighting to 80% output or less based on a demand response signal. Demand responsive lighting control is an option for load management credits (see comments on section C406) and is also an appendix that may be adopted for enforcement by the local AHJ.
• C405.2.10 – Sleeping units and Dwelling units in hotels, motels, and vacation timeshare properties are now required to be provided with switched receptacles.
• C405.13 – Submetering is now required for new buildings with not less than 10,000 square feet of conditioned space; this threshold has been reduced from 25,000 square feet in the 2021 version of the code.
• C405.13.7 – Submetering is now required for non-electrical end-uses. The listed uses are heating and cooling systems, including but not limited to boilers, chillers, and furnaces, and district heating and cooling energy, fuel-fired service water heating, process loads, and other miscellaneous loads such as fireplaces, swimming pools, spas, gas lighting, and snow-melt systems.
• C405.15 – inclusion of on-site renewable energy systems in commercial buildings at a rate of not less than 0.75 Watts per square foot of gross conditioned floor area, not to exceed the combined gross conditioned floor area of the three largest floors. If provisions for on-site renewable energy are not met, then procurement of off-site renewable energy is required.
• C406 – The 2021 version of the IECC implemented a new credit system for compliance with the Additional Efficiency Requirements section of the code. This allowed the design team to collaboratively select credits that align with their design decisions to collectively achieve the minimum 10 required credits. The 2024 version of the IECC has taken this credit system one step further. The required number of credits is now based on the building occupancy group and climate zone. These latest enhancements further highlight the importance of an integrated design as well as identifying which credits should be targeted early in the design process.
• C408.2 – The exception threshold for requiring commissioning on mechanical and service water heating systems has been revised. The changes will result in even more projects requiring code minimum commissioning services. Now buildings must be less than 10,000 square feet and have a combined cooling, heating, and water heating capacity lower than 960,000 Btu/h to not require commissioning of these systems. The exception threshold was strictly based on equipment capacities (480,000 Btu/h for mechanical cooling capacity and 600,000 Btu/h combined service water heating) in the previous version of the code.
• C408.3 – This section now includes functional testing of automatic receptacle control along with expanded testing requirements of lighting controls.
• C409 – A new compliance path has been added specifically for HVAC systems based on a metric described as Total System Performance Ratio (TSPR). An energy simulation would need to be performed to determine the performance of the proposed HVAC design compared to the standard reference design. Compliance with this section would be in lieu of the prescriptive requirements from section C403. This new compliance path applies only to certain building occupancy and HVAC system types.

International Mechanical Code (IMC)

• IMC 403 – mechanical ventilation requirements were added for animal care and treatment facilities, as well as outpatient healthcare facilities to align more closely with updated versions of the ASHRAE 62.1 ventilation standard.
• IMC 508.1.1 – The 2024 version of this section is more explicit than previous versions in what should be provided for commercial kitchen hood make-up air. This section now states that the kitchen HVAC system shall be increased in capacity to accommodate the additional heating and cooling load from the make-up air or dedicated systems shall be provided to, at a minimum, temper the make-up air coming in. This section no longer allows unconditioned make-up air to be utilized without additional heating or cooling capacity being provided. The updated verbiage will likely push more kitchen HVAC designs toward utilizing dedicated outdoor air systems to both condition commercial kitchen spaces and provide the necessary make-up air to maintain appropriate building pressurization.
• IMC Chapter 11 – Incorporates provisions for Group A2L and B2L refrigerants, reflecting advancements in refrigerant technology and a shift towards lower global warming potential (GWP) substances. These additions include specific requirements for leak detection and alarm systems, particularly where safety relief valve discharges are not readily visible to occupants.

International Plumbing Code (IPC):

• IPC 104 – Duties and Powers of the Code Official has been expanded and reorganized.
• Chapter 2 – Definitions have been added for “ambulatory care facilities”, “family or assisted-use bathing rooms”, “family or assisted-use toilet facilities”, and “service sink”. Additionally, “single user” and “multiple user” toilet facilities are now differentiated and defined.
• IPC 305.8 – introduces provisions for the support of buried piping beneath buildings in areas with expansive soil conditions. This change addresses potential issues related to soil movement, ensuring the integrity and longevity of plumbing systems in susceptible regions.
• IPC 306.2.4 – Tracer wire is not required for plastic sewer piping.
• IPC 312.4 – A requirement is now identified for vacuum testing of drainage, waste, and vent systems.
• IPC 403.1 – Significant revisions have been made to the plumbing fixture requirements for various Group I occupancies, which encompass institutional settings such as hospitals, nursing homes, and correctional facilities. Previously, the IPC did not distinctly address the differing needs of patients, employees, and visitors in these settings. The revised code now provides clearer guidelines to ensure that each group’s requirements are appropriately met, enhancing both functionality and compliance within institutional environments. Additionally, the code introduces specific provisions for ambulatory care facilities and outpatient clinics, which acknowledge the unique demands of these medical facilities compared to other business environments.
• IPC 412.12 – Electrically heated or cooled water dispensers are now addressed separately, rather than under Section 410 Drinking Fountains. The applicable standard ASSE 1023 is now referenced.
• IPC 419.6 – Soap dispensers are now explicitly required for public lavatories.
• IPC 501.9 – Conformance with NSF 372 “lead-free” requirements is now explicitly indicated for water heaters that are part of a potable water distribution system.
• IPC Table 604.4 Maximum Flow Rates and Consumption for Plumbing Fixtures and Fixture Fittings, 2.5 gpm shower heads are no longer allowed. Shower heads must now adhere to a 2.0 gpm maximum flow rate and comply with the “high efficiency” requirements of ASME A112.18.1-2020/CSA B125.1.
• IPC 607.2.1 Commercial Energy Provisions – The updated code streamlines the previous verbiage regarding hot water and now defers to the International Energy Conservation Code.
• IPC 702.6 – Chemical waste system section has been expanded, and a new Table 702.6 identifying acceptable pipe and fitting materials for chemical waste drainage has been added. Relatedly, Chapter 9 has been updated with complementary verbiage that addresses the vent pipe material associated with chemical drainage systems.

International Fire Code (IFC)

• IFC 104 – Duties and Powers of the Fire Code Official has been expanded and reorganized.
• IFC 105 – An operational permit is required for an accumulation of more than 15 cubic feet of lithium-ion and lithium metal batteries.
• IFC 107 has been added, addressing the permitting of temporary structures.
• Chapter 2 Definitions has been revised and now includes definitions for “computer rooms”, “data centers”, “emergency responder communications enhancement system (ERCES)”, “hybrid fire-extinguishing systems”, “puzzle rooms”, and “vegetative roofs”.
• Occupancy Classification and Use is no longer captured under Section 202 General Definitions. Instead, it is now in its own Section 203.
• IFC 320 – A new section has been added with requirements specific to the storage of lithium-ion and lithium metal batteries. Relatedly, Chapter 4 Emergency Planning and Preparedness now has specific requirements for occupancies with activities involving such batteries.
• IFC Section 903 changes include:
  • Various occupancies that involve lithium-ion or lithium metal batteries are identified as requiring automatic sprinkler protection.
  • The NFPA 13R sprinkler criteria for group R-2 occupancies are now addressed separately from the criteria for other residential occupancies.
  • The supervisory and alarm requirements related to control valves for automatic sprinkler systems are now specifically addressed under Section 903.4. The signals for alarm, supervisory, and trouble conditions must now be distinctly different. Additionally, there are now specific requirements for sprinkler water flow alarms related to the building fire alarm system.
• Section 904 – Hybrid fire-extinguishing systems (which utilize a combination of atomized water in conjunction with inert gas) are now acknowledged and must be provided per the relevant standard, NFPA 770.
• IFC 915 – Carbon Monoxide (CO) alarm and detection are now required for all types of occupancies and not just residential (type R) and school (type E) occupancies.

When new codes are updated and adopted, it is imperative to spend time identifying the requirements that will affect our projects. By understanding and implementing these updates, design and construction professionals can enhance the safety, functionality, and sustainability of built environments, aligning with the evolving standards of the industry. We hope that this summary helps identify some of the key points. If you have questions about the new codes and how they will affect building design and construction, please reach out to us.