What causes an earthquake? 

An earthquake is a natural shaking of the ground, caused by the sudden slipping of rock on a fault-line. Seismic waves spread outward from the fault rupture much like ripples do in a quiet pond when a stone is thrown into it.

The earth is covered with continent-sized slabs of rock floating in slow motion on a sea of heavier semi-molten material. These slabs of rock are called tectonic plates. They are constantly crunching, grinding, moving into, under, over, and past each other. Tremendous pressures build up as the plate edges lock against each other. Every now and then accumulated pressures will force the edge of one massive plate past the other releasing the spent up energies of uncounted centuries.
Sometimes the plates only jump a tiny bit causing windows to rattle. Other times the displacement is so violent that it sends seismic waves booming out in all directions with forces similar many many atomic bombs. The result is called an earthquake.

Are earthquakes inevitable?  

The Federal Emergency Management Agency (FEMA) reports that scientists unanimously agree on the inevitability of major earthquakes in California. We may never see any degree of pin point accuracy.

We are told by Caltech scientists that studies now indicate strong evidence of a 7+ quake occurring in our area of Southern California within the next two decades. But you can be sure that the further we get from the last earthquake the closer we are getting to "the promised big one".

The Southern California Seismic Network records more than 10,000 earthquakes in an average year. Not including aftershocks, about 100 earthquakes larger than 3.0 occur each year.

Geologists can demonstrate that at least eight major earthquakes have occurred in the past 1,200 years with an average time spacing of 140 years, plus or minus 30 years. The last such event occurred in our area in 1857.

What could happen to an unbolted home in the next strong earthquake?

 What are cripple walls?  Why are they so dangerous? 

A cripple wall is a short stud wall that extends from the top of the perimeter foundation upward to carry the floor joists. The danger comes from the fact these components are in the seismic load path and are often inadequately braced. They can collapse like dominos in a large earthquake. Take care, not all homes have cripple walls but that won't stop some contractors from offering bracing for them. Click here for a larger picture of a cripple wall.

Can any type of foundation be reinforced? 

Any foundation can be made safer. There are different solutions for different materials. A brick foundation can be retrofitted with embedded anchor bolts, and deteriorated mortar can then be flushed out and reconditioned with high density mortar.  

My arroyo stone foundation seems to be falling apart.  Is it too late for me to think about reinforcement?  

Not at all! In fact, we can restore your foundation to better than its original integrity. Then we can anchor the house to it using state-of-the-art materials and specialized seismically engineered procedures. 

How much does reinforcement cost for brick or stone, compared to replacing  the entire foundation? 

You can figure from about $115 per linear for retrofitting, to more than $300 per linear foot to replace a perimeter foundation. Total replacement is rarely our recommendation: however, the choice is yours and we are happy to furnish estimates. 

A contractor friend says we don't need permits or engineering for this kind of work.  Is he right?  

 It is unlawful to perform this kind of work without permit. Fines and penalties are heavy for violation. In addition you'll need both engineered details and a signed permit to satisfy disclosure laws when you sell, buy insurance or apply for a loan. Some cities are waiving permit and inspection fees to encourage homeowners to bolt to their foundations.
If any contractor tells you that permits and engineering details are an unnecessary expense, he is not acting responsibly.

What is the cost of retrofit for a typical home? 

Every home in the "needs retrofit" age bracket has unique differences with respect to height of the structure, profile, perimeter footprint, access to the work area, the materials and condition of the foundation, presence of cripple walls, and settlement problems. These are just a few variables that will affect the final cost. For example, a two-story home requires 50% more anchor positions than a one-story structure. A home with stepped foundations requires a minimum of two anchors per step, and so on.

So you see there is no such thing as a typical home for us to describe here. But everyone seems to like ballpark figures; we find they can be misleading. However, in our recent experience we have completed several projects for as low as $1,700, many between $3,000 and $5,000, a few with major complications ran as high $10-12,000.
Call our 1-800-300 BOLT (2658) for some friendly free phone consultation. 

Will bolting really increase the value of my home on the open market? 

Given a choice between two properties, a potential buyer will naturally choose the more secure home, or expect to pay less for the seismically deficient home.  

 Are insurance companies really refusing renewal for homeowner policies on unbolted homes?  

Absolutely, and lending institutions will soon follow. The reasoning is quite simple: why should we risk money on an investment whose life expectancy might be in jeopardy?