ICC Ad Hoc Committee on Tall Wood Buildings Has Approved 14 Code Proposals
The ICC began this two-year process by appointing a broad consensus committee to ensure that all aspects of TMTB and the IBC were carefully evaluated. The Committee’s membership included:
- Current and former building officials from several regions;
- Architects and engineering experts;
- Fire protection engineers and the fire services community;
- Multiple materials industry groups;
- Planning officials and other construction industry stakeholders.
The Committee’s work was aided by fire resistance testing of several TMTB structures by the federal ATF Fire Research Laboratory, the world’s largest fire investigations lab. The tall mass timber structures exceeded current code requirements in all cases.
The codes that the committee has proposed are intended to assure the public and the fire service that code compliant tall wood buildings will be safe and strong, with rigorous and redundant systems of fire protection.
Below are the code proposals and summaries of their corresponding effects. For a summary of the proposed changes, click here.
Updates the previous definition of Type IV construction and creates the Type IV A, Type IV B, and Type C designations for different types of mass timber constructions. Type IV A is completed protected mass timber construction; Type IV B allows for some exposed wood surfaces of the ceiling, walls, and beams; and Type C allows fully exposed mass timber.
Adds text outlining how tests to establish the fire resistance rating of mass timber components are to be conducted.
Outlines a method to determine the contribution of noncombustible protection to the fire resistance of mass timber.
Requires Types IV A, IV B, and IV C buildings to have sealant at the abutting edges and intersections of mass timber components and at the abutting intersections of mass timber components and components of other materials.
Changes what fireblocking consists of to recognize that mass timber is a suitable fireblocking material.
Requires mass timber Type IV A and IV B buildings over 120 feet to have fire pumps connected to at least two water mains.
Expands the requirements of owners to inspect all required fire-resistance-rated construction to include mass timber walls and ceilings.
Details fire safety requirements for mass timber buildings while they are under construction.
Lays out the allowable building height for Type IV A, IV B, and IV C structures.
Lays out the allowable number of stories for Type IV A, IV B, and IV C structures.
Lays out the allowable area for Type IV A, IV B, and IV C structures.
Creates the Type IV-HT structure category for heavy timber frame-supported structures to differentiate them from mass timber structures.
Ensures consistency regarding the Type IV-HT category for heavy timber construction, distinguishing it from mass timber.
Details requirements for mass timber elements serving as fire barriers or horizontal assemblies to separate occupancies.