Significant changes to concealed spaces in Type IV-HT of the 2021 International Building Code

A modification to Section 2304.11 (Concealed Spaces in Type IV-HT) of the 2021 International Building Code states that concealed spaces are now permitted in floors and roof decks for Type IV-HT.

Historically, concealed spaces have not been permitted in traditional heavy timber construction. Now, concealed spaces are permitted in traditional Type IV-HT construction, with specific requirements for their protection. New protection options include:

• In fully sprinklered buildings, installing automatic sprinkler protection in the concealed space.
• Filling the space with noncombustible insulation.
• Protecting combustible surfaces with not less than 5/8-inch Type X gypsum board.

Concealed spaces in new Types IV-A, IV-B and IV-C construction are addressed separately. The option of having protected concealed spaces in Type IV-HT buildings is important for encouraging adaptive re-use of existing heavy timber buildings as well as providing for the installation of mechanicals (MEP) in Type IV-HT cross-laminated timber construction.

Read the full significant change.

The 2021 Significant Changes guides are available for the International Building, Fire, Residential, Energy Conservation, Plumbing, Mechanical and Fuel Gas Codes. This valuable series can help any code user save time by zeroing in on the most critical changes in the 2021 International Codes. The Code Council’s technical experts provide summaries, analysis and graphics for these changes making them clear and easy to understand. Each edition provides a comprehensive analysis of significant changes since the 2018 edition, offering key insights into its contents and implications. Each change analysis features the affected code sections and identifies the change with strikethroughs and underlines to show modifications to the existing language. Each change is accompanied by a quick summary, detailed illustrations, and a discussion of its significance, which brings the technical jargon of the code to life in a real-world setting.

Significant Changes to the International Building Code, 2021 Edition is available in the ICC Store or through Digital Codes Premium.