Anchorage builders group says the building code already accounts for quake risk

The Anchorage Home Builders Association is urging the Assembly to reject a version of a proposed housing overlay that would leave out the city's two highest-hazard earthquake zones. The Assembly is scheduled to vote on the overlay Wednesday.

The overlay, from Assembly members Erin Baldwin Day of Midtown and George Martinez of East Anchorage, would ease zoning rules for duplexes, triplexes and cottage courts near the city's transit corridors. A substitute from Midtown Assembly Member Janice Park would keep it out of Seismic Hazard Zones 4 and 5, the parts of the city its maps rate most prone to ground failure in an earthquake.

The association supports the sponsors' version and opposes Park's. On the earthquake zones, it argues the building code already accounts for the risk.

"We don't haphazardly build in these seismically active areas," association President Skyler Quinn wrote in a letter to the Assembly, pointing to how Anchorage housing held up in the 2018 earthquake.

"Let sound engineering, responsible development, and the market help determine where Anchorage grows," the letter says.

City code sets extra requirements for small homes in those two zones. Homes of up to three units there need a site-specific investigation and a structural design stamped by an Alaska-licensed civil engineer, according to a memo from Mayor Suzanne LaFrance's administration. Most home sites elsewhere in the city need neither.

The city's Geotechnical Advisory Commission says building codes shouldn't be the only consideration there. The building code is aimed at keeping buildings from collapsing to protect lives, the commission said in an Oct. 1 resolution, and the impact of large ground failures "has not typically been adequately accounted for in design."

"Building codes do not limit exposure to seismic hazards," it says.

The commission urged city officials to weigh the risk of ground failure in Zones 4 and 5, while saying it isn't possible to limit all development there. The resolution doesn't mention the overlay.

Quinn also told the Assembly at its Oct. 7 meeting that the substitute would reach beyond Zones 4 and 5. The city is updating its hazard maps, and builders won't buy land in Zone 3 if it might be moved up to Zone 4, he said.

"So Zone 3 is dead in the water out of the gate on this thing if it passes," Quinn said.

The new maps should be ready for review "in the new year" and are likely to look vastly different from the current ones, the administration's memo says. The Assembly voted Oct. 20 to ask city staff to study what those maps should mean for building and zoning rules once they're out.