Proponents of two historic code changes—one to allow taller mass-timber buildings and the other to allow use of higher-strength reinforcing steel—are optimistic after recent ballots at two different meetings moved the proposals closer to acceptance by code officials and standards developers.
According to a report in the Engineering News Record, the American Concrete Institute committee that oversees ACI 318, Building Code Requirements for Structural Concrete and Commentary, on Oct. 17 in Las Vegas, gave preliminary approval for the use of high-strength rebar in several seismic applications.
The other historic change would be the adoption of provisions, also in the 2021 IBC, to allow mass-timber framing in residential and office buildings as tall as 270 ft. On Oct. 24, at the ICC’s final action hearings in Richmond, code officials voted 220 to 103 to increase the height limits for mass timber buildings, according to Mike Pfeiffer, ICC’s senior vice president of technical services.
The ICC’s online voting, which runs for two weeks beginning mid-November, will determine whether the primary proposal, called G108–along with the other 13 related proposals on mass timber also approved on Oct. 24–will actually be included in the 2021 IBC. Preliminary results of the online tally will likely be announced in mid-December.
Official results will not be announced until early to mid-January, after the ICC’s validation committee, called the technical activities committee, reviews both the proposals and an outside audit of the online voting, and reports to the ICC standards board. The board has the final say.
ICC’s ad hoc committee on tall wood buildings (TWB) “studied mass timber construction for two years prior to introducing these code change proposals, including conducting numerous fire performance tests,” said the American Wood Council (AWC), in a statement released after the Oct. 24 vote. “The result of that rigorous process is that each of the new proposed construction types has had its fire and life safety performance confirmed, resulting in a robust building performance.”
TWB is introducing three new types of construction for the Type IV classification of buildings, each with different height possibilities based on occupancy classification and the design of the mass-timber system.