If you have lived in the area of San Francisco or Oakland for a long enough time, then you have probably experienced an earthquake. Depending on the magnitude, it can be a frightening experience and it can cause a significant amount of damage. To prevent earthquake damage to the home, some structures may need to have some degree of seismic upgrade or retrofitting.
When a home gets a seismic retrofit, it is being upgraded in a way that will protect the structure from earthquake damage. For the most part, this is only going to be necessary for older homes. Newer homes are at less of a risk because we now have a better understanding of the way that seismic forces affect a structure and we have developed engineering techniques that can effectively mitigate much of the damage that will be caused. However, homes that were built before the 1990s predate this knowledge and the development of these techniques.
If you are talking about seismic retrofitting, you might consider a few different things depending on the home. With most homes, the greatest risk is the possibility of the home displacing from the foundation. To protect against this, the connections between the home and the foundation need to be strengthened. As additional concerns, you may also need to protect against things like cripple wall collapse and soft story collapse.
When it comes to preventing the displacement of the structure from the foundation, the seismic retrofit will usually require things like anchoring and bolting the home to the foundation. In this process, anchor bolts are used to secure the sill to the foundation. Another issue could be anchoring the mudsill to the foundation. With steps like these, you are ensuring that the home is securely attached to the foundation, and this can prevent a considerable amount of earthquake damage.
As another possibility, you may need cripple wall bracing as a part of your seismic retrofit. A cripple wall is basically a short wall that goes in between the foundation and the home. When a home is built on cripple walls, it could be exposed to the possibility of cripple wall collapse in the event of an earthquake. To prevent the possibility of collapse, you would need to have the cripple walls braced. Most cripple walls are not strong enough to withstand the lateral forces of an earthquake. By using various bracing techniques, the walls can be strengthened in a way that will prevent an earthquake related collapse.
A soft story collapse occurs when you have living space built above an area that is open and does not provide adequate support. In the event of an earthquake, the room above can collapse down onto the space below because there is inadequate shear strength. To protect against this, you may add shear strength by bracing the walls with plywood or by adding steel framing.
If you live in an older home that has not had the necessary seismic upgrades, it is important that you do not ignore this issue. An earthquake can cause great damage, and the retrofitting can prevent damage that would cost many times the cost of the upgrades. As an additional point, the upgrades can protect the value of your property and the lives of the people within the structure. Even with a seismic retrofit, some damage is still possible, but you are preventing the most serious damage.
If you are a homeowner in the Oakland or San Francisco area, contact Montclair Construction for seismic retrofitting and foundation repair. We have a vast experience with foundation work and we can ensure that your home has all of the protection that it needs from earthquake damage. Call us now to schedule a consultation and inspection.