Get Your Home Earthquake Ready
If you live in Oregon and Washington, you live in an earthquake-prone area. This is also known as an active seismic zone due to the proximity to oceanic plates. Living in the Pacific Northwest, you must be prepared for the next tremor at a moment's notice. Your first line of defense is creating an earthquake action plan in case disaster strikes. In order to make sure you and your home are less vulnerable when a quake hits, it's critical to strengthen your home ahead of time. Seismic retrofitting reinforces your home's structure to ensure that the foundation, floor, and walls are fastened together and bolted down from below the ground up. Work with a licensed contractor, like the experts at TerraFirma Foundation Systems, to reinforce your home's structure rather than trying to do it yourself.Get a FREE Quote
Here are common types of retrofits you can ask your System Design Specialist about:
Repairing and Bolting the Foundation:
Is your home's foundation solid enough to withstand the attack if an earthquake struck today? Older homes, like the ones typically found in Oregon and Washington are especially in danger of having frail, cracked foundations. Seismic retrofitting starts with repairing a weak foundation so it's more stable, secure, and resistant to damage from earthquakes. It's also important to ask your contractor if your home is properly bolted to its foundation. Foundation bolting attaches your home's wood frame to the foundation with anchor bolts and metal plates.
Bracing Cripple Walls:
Another smart upgrade involves adding plywood sheathing to shore up the cripple wall or the short wood wall, which extends from the foundation to beneath the floor of the house. If the cripple wall is not stiff enough, it can literally cripple your main floor, buckling under the pressure of an earthquake..
Reasons to retrofit:
- You reside in an active seismic zone (See map)
- You and your home will have a better chance of surviving an earthquake
- To improve your home's ability to act as shelter after a seismic event
- To reduce the cost of repair following an earthquake
- Retrofitting your home can potentially reduce earthquake insurance premiums and deductibles
Before you begin a retrofit project, it's important that you are familiar with the basic principles of residential construction and how earthquakes impact your home.
Earthquake Basics: Lateral and Uplift Forces
During an earthquake, a house experiences two types of forces: lateral forces and uplift forces. Lateral (or shear) forces are horizontal forces that result in back and forth (side to side) movement, also known as racking. Lateral forces can shake the house and weaken its frame and cause it to slide off the foundation.
Uplift forces are vertical forces that result in up and down movement. Uplift forces can cause the house to overturn and lift off the foundation. Using a continuous load path throughout the home strengthens the entire structure and helps it to resist lateral and uplift forces.
Earthquake Basics: Continuous Load Path
Building codes now require houses to meet higher structural design standards, including the use of a "continuous load path." This method of construction involves creating a series of solid connections throughout the structure. These connections are created by using a system of wood framing, metal connectors, fasteners (like nails and screws) and shear walls.
These connections are critical during an earthquake. A continuous load path redistributes external forces from an earthquake by transferring these forces from the frame of the house to the foundation. A home is more likely to withstand an earthquake and stay intact when each part of the house is connected together.
In general, houses built within the last 25 years should have been constructed with a continuous load path. To confirm this was done in your home, you can hire a professional contractor or qualified design professional to perform a structural evaluation of your house. When hiring a design professional, you want to make sure they are licensed to practice in your state and have a good reputation. You should ask for references and check with the Better Business Bureau.