It is finally here — the 10th edition of the Massachusetts State Building Code (780CMR). The highly anticipated code change has been formally approved and is now in effect as of October 11, 2024.
The 10th edition is based on the 2021 International Building Code (IBC) with state specific amendments. Since the 9th edition was based on the 2018 IBC, this current update will effectively capture two versions of IBC changes. To help with the alignment of current design practices and new codes, there will be a concurrency period allowing either version to be used for a limited time. Projects will be able to use either the 9th or 10th editions of 780CMR until January 1, 2025. After January 1, 2025, all projects will need to submit based on the 10th edition codes only.
Code updates often prompt questions about changes in design approach, testing methodology, and compliance paths, especially if they incur additional costs to a project. While new construction code requirements are straight forward, an existing building requires an understanding of potential challenges to help with evolving market demands and project feasibility aspects.
Existing buildings are often constructed with an initial use group in mind. Since usage may change over time, it is important to understand what a structure was originally designed for as much as it is helpful to know what it is being currently used for. Changes in use often trigger a review of multiple aspects of building infrastructure, ranging from health and safety to energy efficiency.
A use change could therefore impact egress calculations, fire ratings, and plumbing fixture requirements, just to name a few. The latest version of the building code includes expanded guidance, including expanding lists on institutional uses. It should be noted that some of these require additional structural review or upgrades such as addressing seismic reinforcing for compliance.
In some cases, a change in use may require an addition or certain amount of alteration to a facility. It is important to define the percentage of the work area early to confirm the level of building alteration. Depending on project scope, compliance with new construction requirements or testing of existing elements may be necessary. As a continuation of a due-diligence effort, an egress and occupancy load calculation should be reviewed since there were some changes to the 2018 IBC that are now being formally implemented.
Important Change in Occupancy Rules
The 10th edition has a notable change in occupancy area calculations with business use changing from 100 SF to 150 SF per person. This simple change would alter a maximum allowable load in a 10,500 SF space from 105 down to 70. This may still be permissible with other factors and design considerations such as appropriate egress pathway sizing that includes appropriately sized doors and stairs, but it should still be noted.
As sustainable construction grows, the focus on carbon footprint for both existing and new buildings continues to evolve. To help with this, there is a significant expansion of construction type IV, which had historically been thought of as heavy timber construction but has expanded to include definitions and methodologies of Mass Timber construction and includes information for sub-types A, B, and C. This is important since any additions to existing structures may now have additional compliance path options.
Additional elements for consideration are the insulation and vapor barrier aspects of wall and roof assemblies. While some of these have already been captured in the energy stretch codes, the 10th edition base code now raises the minimal amounts required for certain conditions. Accommodating for the additional dimension inboard or outboard should be understood.
All the code changes put Massachusetts in a better place to address the current needs of our built surroundings, balancing the needs of life safety, public health, and sustainability. However, it will still be up to project teams to ensure that the triggers and dimensional changes created by these changes are understood early on in a project as we adapt to the new codes.