January 26 was the 323rd anniversary of the 1700 Great Cascadia Earthquake. It was a magnitude-9 event that is expected to reoccur with a one-in-ten chance in the next 50 years. The annual date is a good time to candidly check on how your home earthquake-retrofitting is progressing.
For homes built before the mid-1990s, the following questions are relevant:
• Is your water heater bolted to the wall?
• Is the house bolted to the foundation?
• Are basement posts and beams reinforced to resist strong swaying of the house above?
• Are floor joists braced to prevent their collapsing sideways?
• Is selected wall framing reinforced with horizontal 2x4s when there is an opportunity (for example, during the course of other remodeling)?
As much of this is straightforward, it can be done DIY. Other aspects may require help from specialists.
The goal is to make your home resistant to five minutes of severe lateral shaking, which older homes were not built to withstand. The open-cell 2×4 wall framing was mainly designed to support the roof against gravity (vertical load-bearing).
To see the concept of lateral strengthening, pause the next time you pass a construction site to examine how many horizontal 2x4s are in the walls, which are lacking in older homes.
The retrofitting need not cost thousands of dollars. Start with the easy stuff. Keep an eye on recycled architectural supply shops for metal hardware (Second Use & Earthwise). Repurpose scrap lumber.
Use screws (stronger), not nails.
Some of the author’s DIY (do-it-yourself) basement retrofitting. Above: Reinforcing post/beam connections is an easy fix. Below: Other easy fixes require wall and ceiling access. Here, added horizontal 2×8 and 2×6 boards will prevent adjoining joists from collapsing. Below them, new metal hardware reinforces connections between the basement framing and the first floor to prevent entire-floor sliding. All such basement ceiling reinforcement is being left visible intentionally, so the next homeowner can see what has been completed and what has not.
