October is Earthquake Preparedness Month
When it comes to resilience during a major earthquake, some homes perform better than others. This largely has to do with when a structure was built — more specifically due to the building standards at the time of its construction. Homes built before 1985, for example, and particularly those built on raised foundations, can be especially susceptible to earthquake damage.
Fortunately, advances in structural engineering, lessons learned from past earthquakes and scientific research have paved the way for construction techniques that better equip homes to withstand a seismic event. And local and regional building codes now require all new houses in seismically vulnerable regions to meet higher construction and safety standards.
If you live in an older home, there are steps you can take to strengthen it. Our resources are here to help you evaluate your home’s resilience and safeguard against earthquakes and other natural disasters.
Protecting Homes Against Earthquakes
October is Earthquake Preparedness Month, and October 15 is the Great ShakeOut earthquake drill. In this Simpson Strong-Tie blog series, we thought we’d share some steps homeowners can take to help minimize the risk of damage from earthquakes. Depending on your location, you may find further information and resources at the end of each blog post, with links to local cities that participate in resiliency plans for homeowners and contractors.
If an earthquake were to strike at this very moment, are you confident your home is adequately constructed to withstand its forces?
Depending on what part of the country you live in, as well as on how and when your home was constructed, an earthquake could have a devastating impact on your physical and financial health.
In the western US where earthquakes are most frequent because of its active fault lines, new single-family homes and multifamily units also dominate the marketplace, with about 80% of all buildings constructed from timber. These newer homes and buildings are less likely to experience damage from an earthquake because they have been built to strict building codes and with a continuous load path — a method of construction that essentially ties a home together, from roof to foundation, using metal connectors, shear walls, and fasteners. A continuous load path works to redistribute the forces of an earthquake through the entire frame of a home including the roof, walls, floors and foundation, which better enables a home to resist damage.
Yet, many existing homes and multifamily buildings were constructed prior to the new earthquake-resistant building requirements. The key to protecting these older homes and buildings from earthquakes is retrofitting. Retrofitting adds bracing and reinforcement to the critical connections within a home, including bolting the home to its foundation.
How to Strengthen the Frame of Your Home
Building with a continuous load path strengthens the structural frame of your house. So what is a continuous load path? It’s a method of construction that uses a system of wood, metal connectors, fasteners (like nails and screws) and shearwalls to hold the structural frame of the house in one piece. A continuous load path is like a chain that ties the house together from the roof to the foundation.
A continuous load path is critical during an earthquake because it helps hold the house together when ground forces try to pull it apart. A home is more likely to withstand an earthquake and stay intact when all parts of the house — roof, walls, floors and foundation — are connected to each other.
Homeowner Earthquake Checklist
An earthquake-safe home is characterized by the following:
- Wood walls around the perimeter of the home are secured to the foundation, using anchors, bolts, sill plate connectors and holdowns (i.e., connectors specially designed to help hold framing down to its foundation).
- Metal strap ties or holdowns are used to connect the second floor to the first floor.
- Beams and joists are joined together with metal connectors and fasteners (the critical points within the frame of a home are where two pieces of framing material meet).
- Metal connectors are added to connect the roof to the wall top plate.
- Post-to-beam connections are reinforced with metal connectors.
- Minor foundation wall cracks are repaired with epoxy.
- Code-listed products such as those from Simpson Strong-Tie have been used. Not all structural products are alike or code approved. Simpson Strong-Tie takes great pride in manufacturing the highest-quality metal connectors, anchors, fasteners and shearwalls that meet or exceed all code requirements.
For more info and seismic solutions visit strongtie.com/solutions/seismic
KEY SEISMIC RETROFIT RESOURCES
Earthquake Brace + Bolt Program
California Earthquake Authority