Modern buildings are designed to handle a significant amount of snow. But as Kennewick and Pasco saw Wednesday morning, buildings do occasionally fail when the white stuff starts to accumulate.
In Pasco, a roof over a dock at the Pasco Boat Basin sagged under the weight of the wet snow. Across the Columbia River, a vacant building owned by the Port of Kennewick caved in early Wednesday.
No one was hurt, and the building, a 1950s era warehouse formerly slated for redevelopment, is insured. But the incidents beg the question: Has 2017’s snowpocalypse reached the limits of what most Mid-Columbia roofs can safely handle?
Building officials say no, at least not yet.
Modern building codes require roofs to handle up to 20 pounds per square foot, or 20 to 24 inches of snow depending on moisture. A cumulative 23.1 inches have fallen on the Tri-Cities this season, but some of that has already melted.
The building that collapsed in Kennewick went up in the 1950s, before the 20-pound rule took effect. It’s unclear what exactly triggered the collapse. The Port of Kennewick retained engineers last week after the roof started to buckle, but they weren’t able to examine it before the disaster struck.
“They were doing everything they could,” said Tony Ostoja, Kennewick’s building official.
Ostoja said newer buildings and homes can easily handle the snow that’s accumulated so far. Like his peers in Kennewick and Richland, he suggests caution and a watchful eye.
“If the snow continues as it is, it might be prudent for older buildings to consider removing snow to avoid any problems.”
As a precaution, Kennewick removed the snow from its Dan Frost Municipal Services Complex after questions were raised about the stress on the old downtown building’s roof.
The Benton County building department didn’t know of any problems so far, but Steve Brown, manager, agreed the outlook could change.
“If it keeps going, (roofs) can only take so much,” he said.
Harvey Lighthouse, a structural engineer with Pasco-based Harms Engineering, said the light, fluffy snow that’s fallen on the Tri-Cities isn’t heavy. But that could change if it rains. If that happens, the snow will soak up the moisture and could start stressing roofs.
“With water, you can get to your 20 pounds (load limit) with just three inches of water,” he said.
Around the Tri-Cities, facility managers are keeping tabs on their roof tops and the weather.
At Columbia Center, the 772,400-square-foot shopping center in Kennewick, the operations staff is monitoring snow on the roof and checking to ensure roof drains are ready when it melts, said Jordan Youngs, director of marketing and business development.
Three Richland elementary schools — Tapteal, Badger Mountain and White Bluffs — have flat roofs. Steve Aagaard, the district’s spokesman, said the facilities department is monitoring them.
In Pasco, the school district has not yet had to remove snow from its 22 educational buildings, said Randy Nunamaker, executive director of operations. The district commissioned a structural study on its older buildings a few years ago and they are sound.
Kennewick schools are focusing on buildings with flat roofs. Wednesday afternoon saw crews shoveling snow off Amistad Elementary School.
Troy Hendren, Pasco building official, shares the consensus that newer buildings are safe for the time being. The code may be 20 pounds per square foot, but the reality is typically higher as engineers add margins for safety.
“We have some good engineers out there. They calculate for this. They don’t want failure,” he said.