House Bolting Vs. Earthquake Retrofitting

When we speak of the term “House Bolting,” it is an informal or layman industry term that means bolting the mud sill to the raised foundation of the house, specifications of which are set to local building codes specially chosen and adapted from the International Building Code of the International Code Council.

The process is really what sets the term apart from earthquake retrofitting: house bolting in California is only a part of earthquake retrofitting, as needed, determined by a foundation specialist, while earthquake retrofitting is the encompassing construct to offer earthquake protection at the most minimal level as set by your local building department. One may choose to go above and beyond minimal code requirement, which usually requires advanced civil and soils engineering (and sometimes a geologist) to configure a scope of work, desired results of which may be limited by budget, technology, research, design, planning, labor, materials, or even finding the right contractor.

House bolting to resist earthquake movement and to decrease the chance of earthquake damages incurred by homes and structures as affected by the incredibly violent and unpredictable forces in Earthquake Country — seismic activity being rampant in our service area of Southern California including Greater Los Angeles — is one of the most basic best steps homeowners can take to preserve one of their largest investments: their home.

As we’ve mentioned that house bolting is one part of earthquake retrofitting, retrofitting is the process of adding hardware or components to something that has already been built or designed. Every home is unique and every earthquake retrofitting plan will be unique as well. Common though is house bolting, where the house is bolted down to the foundation, which for most homes in Southern California on raised foundations is necessary (options are available for slab-on-grade foundations as well).

House bolting is implemented on a voluntary basis by the owners of older homes built before the last time codes drastically changed after the Northridge earthquake of ’94. While it is involuntary for new home construction, voluntary is a very formal way of saying: “Local, state, and federal law finds it very difficult to enforce the safest building practice in this area, safest next to residents moving out and moving far, since there are still millions of homes in California without proper earthquake protection, with plenty of known and unknown faults to destroy any and all of them… at any time, on any day, in any weather — and it’s up to homeowners to recognize this and take charge.”

Crucial notes regarding earthquake mythology and house bolting:

1. There is no such thing as earthquake weather. We cannot believe to be shamans of the weather to predict when an earthquake will strike.
2. Dogs and cats and birds cannot predict or bark at an oncoming earthquake. It is possible as denoted by Cal Tech research that they merely identify a silent wave of the earthquake only seconds before the main wave of destruction hits. Animals, like most people, are not shamans. They do not predict; they are literally running for their lives as they react to a physical signal seconds before destruction.
3. If you order house bolting today, then you will have a house bolted by the end of this week. And by the end of this week is better than by the end of next week, considering the circumstance of unpredictability, urgency, and the importance of being prepared.
4. 20,000 people were left homeless after the Northridge earthquake. Many craftsman homes collapsed and were red-tagged by FEMA. One thing these all had in common: the lack of proper earthquake retrofitting.
5. You are responsible for your own aftermath. How you prepare today will determine how you survive during and after the Big One. Federal aid does not arrive UNTIL 72 HOURS AFTER CATASTROPHE! The more time, effort, and capital you invest in it now, the higher quality of life you will experience in a seriously catastrophic event. Simple house bolting will take you, your family, and your home a very long way.

 House Bolting in Three Scenarios:

1. Homes on a raised foundation without perimeter cripple walls will more than likely experience clearance sizes that are at the minimum height of 18”. In this case, house bolting is a simple process of bolting around the perimeter of the interior of the foundation along the mud sill, possibly utilizing foundation plates instead of traditional long bolts due to equipment failing to fit under the tight space of the crawl space (only 18” to move and work). House Bolting Only!
2. Raised homes with cripple walls will more than likely need cripple wall bracing as well as perimeter foundation bolting. This is one of the most common earthquake retrofitting orders. Supply and install cripple wall bracing and house bolting.
3. In either of the above scenarios, if the clearance is less than 18”, then digging will have to take place to create new clearance, which is measured during physical inspection for qualification for final approval from the city. This document, the city permit that allows the work to be done and recognizes that the work is done to today’s building codes, is lifetime transferrable between homeowners.

House Bolting, despite the differences, is sometimes interchangeable with earthquake retrofitting, seismic retrofitting, or foundation bolting.

While very basic house bolting services start at around $2,500, the most expensive Los Angeles earthquake retrofitting job went for about $5,000,000 on top of the few million already invested in its earthquake protection, which was for an emergency operations building in downtown: the one building that first and foremost needs the guarantee of being there for Los Angeles when disaster strikes. They employ something other than house bolting in their earthquake retrofitting technique: the building is on a floating foundation. Using special suspension ball-and-socket steel columns that absorb the multidirectional movements of earthquake shaking, the building literally does not touch the ground. This option is available for homes as well, but usually goes above and beyond most budgets.

Additional House Bolting Components:

Post and pier framing anchors and reinforcement are recommended along with house bolting for extra strength and support during the Big One. These piers are used to help support the bearing load of the floors above and reduces the sinking and sagging of floors.

House Bolting Replacement for Existing Foundation Bolts:

House Bolting is the Best Way to Protect You, Your Family, and Your Home!