Preparing Your Home for the Mega-Quake

Home Ownership

Preparing Your Home for the Mega-Quake

With the West Coast and specifically the Pacific Northwest on notice of their impending doom thanks to the cogent and exhilarating New Yorker article about the inevitable Cascadia mega-thruster earthquake, it seems an appropriate time to discuss preparing your home for such an event.

If you have a modern home, built in the last 40 years or so, your house should be built to at least some version of a seismic code and should be better prepared to resist catastrophic failure than an older house. However, as you will learn, even owners of modern homes can make their homes safer.

If you have an older home, I would consider performing some amount of seismic retrofitting work. Generally, the older the home, the less it was designed to resist the forces of a seismic event.

This article will discuss basics about seismic codes, what you can look for on your own house and give you a few practical tips on how to prepare for The Big One.

Seismic Codes and Retrofitting

The 2012 International Residential Code (IRC) Seismic Design Category map.
The 2012 International
Residential Code (IRC) Seismic Design Category map.

It is important to understand that seismic codes are designed to protect people inside of buildings; they do not result in earthquake proof houses. Structures built to modern seismic codes should be able to resist small and moderate earthquakes with little to no damage and should resist catastrophic failure in even the largest earthquakes. The Seattle area is in the D2 seismic design criteria which is one notch below the most stringent standard of E. If you live outside of Seattle and are wondering what category your area falls into, check out this map from the National Earthquake Hazards Reduction Program (NEHRP).

In addition to resisting structural failure, building codes also cover the installation of home features that can injure and even kill in an earthquake. This includes strapping the hot water heater and installing seismic protection for your gas meter. This is one area that almost every homeowner in the Pacific Northwest can make some improvement. For example, there are no restraint requirements for propane tanks and no automatic shut offs required for gas meters in Washington; presumably this will become code after the earthquake.

How to Prepare Your Home for an Earthquake

Below is a short list of seismic design features you can check for on your house. Remember that comprehensive seismic designs are complex; you can quickly find yourself in a gray area regarding how far to go in seismically retrofitting your house. This article is just a brief overview. If you are interested in more detailed information, I recommend consulting with a local contractor who specializes in seismic retrofitting. The Homebuilder’s Guide to Earthquake Resistant Design and Construction is also a great resource and is available for free on-line.

  1. Make sure your water heater is strapped (here’s a Youtube video explaining how to check it). If your water heater is knocked down it can create water damage and a serious safety hazard with scalding water and disconnected electric or gas lines. This is required for all homes located in a D2 seismic design category.
  2. Install an earthquake gas shut off valve (like this one) for your gas meter. These are currently not required in Washington State but help to protect against gas leaks when pipelines rupture.
  3. If you have a propane tank, make sure it has some type of restraint or anchoring system. This is also not required in Washington State but will protect your tank from falling over and causing an explosion.
  4. Install positive connectors at the joints where posts meet beams and beams meet footings. This is often very inexpensive (the low-hanging fruit of retrofitting) and can greatly strengthen the house. Homes built in the last 25 years will have this, as it is part of modern code. The Eichler Network offers more information on seismic retrofitting.
  5. Connect the wood frame of your house to the foundation so the house will not be thrown off the foundation. This is typically done with lag bolts and washers but there are also some neat metal plates that can be used for retrofitting. (This is part of the modern code in D2 areas).Joist_PonyWall
  6. If you have exposed pony walls (the short wood framed walls between your foundation and the floor joists on your first floor), put plywood between the studs to strengthen the wall. (This is also part of the modern D2 code).
  7. If you have a post and pier, masonry block, stone or brick foundation, consult with a qualified contractor about options for strengthening the foundation. One great option is installing a redundant post and beam system adjacent to a humble foundation, creating a wooden back up support structure in case the old foundation fails.
  8. Lots of people ask me about generators: If you want a reliable generator system to help you after a severe earthquake, consider propane as a fuel source with your own tank. Here are three reasons:
    • It is easier to store propane than gas because gasoline goes bad quickly.
    • It is physically hard and dangerous to have too many gasoline cans around your house.
    • The natural gas lines will likely be disrupted.

What to Have on Hand to Be Prepared

  1. Flashlights and fresh batteries
  2. A battery operated radio
  3. At least two weeks food and water. According to the World Health Organization, short term survival requires a minimum of ½ gallon of water per day, per person. For a family of four this would be 28 gallons…. Yes, that’s almost six, five-gallon buckets!
  4. Be sure you have some back-up means of preparing your food. Assume that electricity and gas will both be off. Camping gear such as tents, sleeping bags and stoves make great back-up survival equipment.

What to Plan

  1. Have an out-of-state contact that every member of your family can contact as a mutual check-in point. Local phone systems could be down for a long time.
  2. If you live or work in a low-lying area, have a plan for getting to high ground as soon as possible, in case there is a tsunami that follows the earthquake.

I hope this brief article helps you better prepare for the big one and I hope we are not around to find out if all your preparation was helpful!

About Dylan Chalk
Dylan Chalk is a home inspector and the owner of Seattle-based Orca Inspection Services LLC – www.orcainspect.com. He is also the founder of ScribeWare software offering innovative and simple report writing solutions. Follow his house-hunting tips from the field on Twitter @DylanChalk1 or on his blog at http://getscribeware.com/blog.

Note: This is a guest post; the views and opinions expressed are those of the author and do not necessarily reflect the opinion or position of Redfin.

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