The Commercial Energy Code technical advisory group voted to remove a long‑standing Washington state exception that allowed concrete masonry unit (CMU) walls with filled cores to meet less stringent prescriptive thermal performance than other mass wall types.

Lede: The TAG approved a proposal to eliminate the CMU core‑filling exception after a lengthy discussion about climate impacts, construction practice and alternative ways to comply.

Nut graf: The exception previously permitted certain CMU assemblies to be treated as if their thermal performance was substantially better than other mass walls — allowing walls with grout‑filled cores to meet prescriptive values that code reviewers said led to higher heat loss in practice. Proponent Dwayne Johnlin said the exception allowed “about four times as much heat loss per square foot” compared with other mass walls. Critics, including masonry proponents and some contractors, warned the change could affect common construction practices used for retail, school gymnasiums and certain garage walls.

Details: Dwayne Johnlin presented the proposal and explained that filled CMU cores create continuous thermal paths in many seismic regions where cores are grout‑filled up to 35% by area; that reduces thermal resistance and raises heat loss. He said alternative design approaches exist — insulated skirts, exposed masonry only at lower interior elevations, insulated framing above the masonry — and that many jurisdictions nationwide no longer keep the CMU exemption. Lisa Rosenow and others supported the change as aligning Washington with national model codes and removing a unique outlier.

Opponents including masonry advocates and contractors urged caution. They noted applications where CMU durability matters (schools, gymnasiums, resilient façades) and said real‑world solar gains on east/west faces can reduce net winter losses in certain climates.

Outcome: The TAG voted to approve the proposal as modified (voice vote). The chair recorded that one member dissented. The TAG also agreed to minor edits suggested during debate — shifting some values into other sections and clarifying below‑grade/foundation exceptions — before finalizing the item for the council package.

Next steps: The approved language will be forwarded to the state code council as part of the TAG’s packet of recommended amendments for the 2024 code cycle. Building departments, masonry trade groups and architects involved in the region were encouraged to note the change and plan for alternative compliance strategies such as continuous insulation or UA trade‑off calculations.