2024 IBC CODE CHANGES

While the 2021 IBC has been adopted by several jurisdictions, with others in the process of updating as discussed below, the code development cycle for updates to the 2024 IBC is now underway. Most notably with respect to tall mass timber is a proposed change to the ceiling exposure allowances for Type IV-B. Under the 2021 IBC, Type IV-B is permitted up to 20% ceiling exposure as noted. However, a planned update would allow 100% ceiling exposure in the 2024 IBC. Several projects currently in design are looking to leverage these future code allowances, and several jurisdictions are including this change in their code amendments and code adoption processes.

JURISDICTIONAL CODE ADOPTIONS

While the list is constantly changing, the following jurisdictions have adopted the tall mass timber provisions in the 2021 IBC, either in whole or with local amendments.

• Oregon
• Washington
• City of Denver
• Utah
• California
• City of Austin, Texas
• City of Bryan, Texas
• Maine
• Georgia
• Idaho
• Connecticut
• Maryland
• New Jersey
• South Carolina
• South Dakota

Several other jurisdictions are considering or are in the process of adopting the tall mass timber provisions or the 2021 IBC in whole. Note that several jurisdictions including Denver and Oregon have already adopted the tall mass timber provisions of the 2021 IBC and will be adopting the 2024 IBC allowance for 100% ceiling exposure under the 2022 Denver Building Code, scheduled to be adopted in the summer of 2022.

THE URGENT NEED TO LOWER BUILDING CARBON FOOTPRINTS

Advancements in tall wood construction and codes are being made just as the call for low-carbon construction reaches new levels of urgency. The built environment is growing at a record pace in the United States. It is estimated that 2.5 million new housing units are needed to make up for the nation’s housing shortage¹⁵.

Buildings and their construction account for 39% of global carbon dioxide emissions; 28% of those emissions come from operational carbon—the energy used to power, heat and cool a building¹⁶. Buildings’ operational carbon can be reduced through energy efficiency measures and policymakers, architects, developers, and engineers have made significant advances in this arena. The remaining 11% of carbon emissions are generated from building materials and construction¹⁷. This embodied carbon can account for half of the total carbon footprint over the lifetime of the building¹⁸.

Embodied carbon is a priority for many environmental, architecture, and urban planning organizations including C40 Cities¹⁹, Architecture 2030²⁰, Urban Land Institute²¹, and the World Green Building Council²². Many experts believe addressing embodied carbon for buildings and building materials is critical to achieving the goals of the Intergovernmental Panel on Climate Change (IPCC) and the 2016 Paris Climate Agreement.

80M - First Mass Timber Vertical Addition Differentiates in D.C.

Photo courtesy of Hickok Cole

A nimble, lightweight, and prefabricated mass timber structure helps make a 100,000-square-foot vertical addition possible while boosting the value of this D.C.-based commercial office complex.

Location: Washington, D.C.
Size: 100,000 square feet
Owner: Columbia Property Trust
Architect: Hickok Cole
Structural Engineer: ARUP
Contractor: Davis Construction
Completion: Spring 2022

As vacant parcels become harder to find in densifying urban centers and business districts, developers are looking at expansion through vertical additions. At a current height of 90 feet (seven stories), 80 M Street was a perfect candidate for vertical expansion, but it also needed to appear unique in the District’s crowded commercial market. To accomplish both goals, architect Hickok Cole chose mass timber for their 100,000-square-foot addition, a first of its kind for the city and the design team. Glulam forms the beams, columns, arches and trusses, while CLT forms the walls, floors and ceiling.

The design team’s decision to use mass timber was driven by a number of factors. Chief among them was timber’s light weight, as the existing building could not handle the load of a traditional concrete addition. Timber’s light weight also proved advantageous by allowing the team to deliver the project more quickly and with less impact to the occupied building.

Once completed, the addition will add two full floors of office space atop the existing 286,000-square-foot building as well as an occupied penthouse level and rooftop terrace for social space. Other design highlights include exposed CLT ceilings and an abundance of connected outdoor spaces that will add nearly 4,000 square feet of outdoor amenity space atop the building.