Earthquake News

During earthquakes, a seismic retrofit can assist to safeguard properties.

Anchoring, bracing, and connecting a home through a home earthquake retrofit is as easy as ABC.

Most homes built in the last 30 years or so do not require earthquake retrofits, but older properties may require foundation repairs. Ground shaking can cause significant damage if the foundation is not properly fastened to the rest of the construction.

The recent earthquakes in Japan, as well as strong tremors in New Zealand, Chile, and Haiti, have refocused attention on seismic safety at home.

"When the ground begins to shake sideways, the foundation moves with it," said Leif Jackson, co-owner of Sound Seismic. "This large, gigantic item isn't going to shift with the foundation right away." It'll lag behind, and it'll lag behind even more when that foundation oscillates back in the opposite manner. As a result, the house and the foundation get out of rhythm, and the home may be jolted off its foundation."

Despite the fact that most homeowners may take basic actions to lessen earthquake risks, older properties are the most likely candidates for a seismic retrofit, thanks to the implementation of current construction rules beginning in the mid-1970s.

 

Before the 2001 Nisqually earthquake reminded people of the region's vulnerability, Jackson and his brother Erik founded the Seattle-based firm in 1999. Every year, Sound Seismic does retrofits around Western Washington, including a few in Issaquah.

Contractors brace the cripple wall, a short stud wall running from the top of the foundation upward to support the floor, during a seismic retrofit. Because the cripple wall is designed to sustain weight from above, side-to-side movement caused by earthquakes can lead it to tumble. The cripple wall is braced by Sound Seismic and other retrofit companies.

Now, let's get back to the ABCs.

Contractors link a house's floor to a braced cripple wall, brace the cripple wall with plywood, and then bolt, or connect, the braced cripple wall to the foundation.

"Certainly, homes built in the 1950s or earlier will not have plywood, anchor bolts, or anything else, so they are absolute candidates for a retrofit," Jackson added.

The tragedy serves as a sharp reminder.

Since the March 11 catastrophe, calls to Sound Seismic have increased tenfold due to the visuals of devastation from Japan — and the inherent seismic danger in the Pacific Northwest.

Cost is the most often asked question by potential clients. The cost varies depending on the home, but crawlspaces (about $4,000 to $6,000) and unfinished basements (approximately $5,000 to $8,000) are less expensive than completed basements (around $8,000 to $15,000).

Building permits are required for seismic retrofits in Newcastle and unincorporated King County.

During a seismic retrofit, chimneys should also be given specific attention. During the 2001 Nisqually earthquake, several chimneys collapsed, leaving a mess rather than disaster.

"Fortunately, most of them dropped away from residences and landed in yards rather than on top of and through the roof," Jackson added.

Homebuilders in the Pacific Northwest also employ tremor-resistant materials.

"In earthquakes, our wood-framed houses are arguably the best-performing building," Jackson added. "There's a lot of give in the wood." It will bend before breaking, and all those nails and wood fibres just add to its flexibility. What this means is that your house is unlikely to collapse in a heap."

"Fortunately, most of them dropped away from residences and landed in yards rather than on top of and through the roof," Jackson added.

Homebuilders in the Pacific Northwest also employ tremor-resistant materials.

"In earthquakes, our wood-framed houses are arguably the best-performing building," Jackson added. "There's a lot of give in the wood." It will bend before breaking, and all those nails and wood fibres just add to its flexibility. What this means is that your house is unlikely to collapse in a heap."

Recommendations for earthquake safety

Many earthquake injuries occur inside a home as a result of people rushing around while the ground shakes. They trip, collide with furniture, walk on shattered glass, or are struck by falling objects. There is a substantially increased risk of shattered windows, fallen bricks, and other harmful debris in and around older structures.

Residents may prepare for earthquakes by following the advice of the local American Red Cross chapter:

  • Water heaters and gas appliances should be bolted and braced to the wall studs. Bookcases, china cabinets, and other tall furniture should be bolted to the wall studs. Fixtures in the ceiling should be braced.
  • Heavy things like portraits and mirrors should be hung away from beds, couches, and other places where people sleep or sit.
  • On cabinets, use robust locks or bolts. Large or heavy objects should be stored in the cabinets closest to the floor.
  • Learn how to turn off the gas valves in your house and have a wrench on hand in case you need it.
  • Before you begin construction, learn about the seismic building requirements and land-use rules in your area.

Ready to retrofit?

Let’s make your home safer

Get a professional evaluation

Call 206-352-5644

 

Sound Seismic
7543 15th Avenue NW
Seattle, WA 98117

Contractor's license # SOUNDSL836ND

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