Posts Tagged ‘Earthquake Retrifitting’

Seismic Retrofitting Facts

Author: The Editor

Seismic RetrofittingSomeone tell me – what exactly IS a “retrofit” – does it make my home safer? Why should I bother? Isn’t my house already “bolted”. . . ?

 

Merriam-Webster’s definition: “retrofit” – to provide (something) with new parts that were not available when it was originally built.

– To furnish (as a computer, airplane, or building) with new or modified parts or equipment not available or considered necessary at the time of manufacture.

Dictionary.com definition: – “Retrofitting” – to install, fit or adapt (a device or system) for use with something older: “To retrofit solar heating to a poorly insulated house”.

So what is seismic retrofitting for your home?

Seismic retrofitting is the process of adding additional hardware, plywood and framing lumber to the foundation area of a building in a way that heightens its readiness and helps protect it during seismic activity. There are very specific methods of how this is to be done and unfortunately many wrong ways to do it as well! If your house is built later than 1936, it almost certainly has some level of “bolting” in place from when it was first built. Standards have of course evolved tremendously since then (imagine the lack of safety features in a 1936 car compared to a current one!) and this is where seismic retrofitting (bolting) comes in. It is employing current structural knowledge into an otherwise antiquated situation to improve its overall ability to help withstand earthquakes and to help protect you from catastrophic loss.

We perform full seismic retrofitting (“house bolting”) to current standards. The exact specifications of this work can be viewed directly via the City of Los Angeles website at www.ladbs.org. Even if you do not live in Los Angeles itself, all cities that we work in recognize the Los Angeles standards and accept them. This includes, but is not limited to Glendale, Burbank, West Hollywood, Beverly Hills, Pasadena, South Pasadena, Santa Monica, Culver City and the list goes on.

We also perform corrections of incorrectly performed or antiquated bolting jobs in order to help protect those homes from future earthquakes. (Statistic: 85% of homes within various cities of Los Angeles county that have been “bolted” since the 1994 Northridge earthquake had the work performed sub-standardly when it was done.) Therefore, only about 15% of the inspections we perform find houses to be properly and fully retrofitted. This includes houses that have been “retrofitted” after the 1994 Northridge earthquake. If your foundation retrofit is sub-standard in some way, we will be able to provide you a recipe for correction to resolve that deficiency and help protect your home from loss in any future earthquakes.

If you’ve not already done so, feel free to call for a complimentary

inspection of your primary residence and at the same time, we would let you know specifically (if anything) is lacking when compared to the current standards that are available!

 

Over the years, I’ve inspected countless thousands of foundations and one of the most frequently asked questions I’ve heard from homeowners’ is this: “Do you think I should bolt the house?”  Well now being a foundation contractor, any answer from me could certainly be viewed as being biased by virtue of what would seem to be a distinct “conflict of interest” on my part, as seismic retrofitting (house bolting) is a service we offer!  It can present itself as somewhat of a “Catch-22” in that if I answer that “Yes, it is a good idea”, I look biased. If I answer that “No, it is not needed”, I may be doing them a great disservice in that there may be things that the house needs to better prepare it seismically. With that dilemma in mind, I have evolved a simple analogy that educates them such that they can then participate in the decision process. Quite simply, the most logical analogy I’ve found and the one that resonates with the majority of homeowners is simply this: house bolting is similar to putting on a seatbelt when you’re in a car; in the event that the car is in an accident, the chances of injury are much less than if one were not wearing a seatbelt and yet even a seatbelt cannot ensure that one will walk away injury-free. Well house bolting is essentially the same thing; a house that has had proper seismic retrofitting done to it has a much better chance of performing well during an earthquake, but also does not fully eliminate the potential of damage to the home.

The other key factor to consider, holding to the analogy above, is that technology evolves. The safety features in say a 1960’s car versus the safety features in a new car have very little in common; the “lap belt” has been replaced with shoulder restraints, air-bags, side impact protection, anti-lock brakes, crumple zones, etc, etc, etc.  As that relates to house bolting, the same is true of how well an older structure is secured versus a newer one.  Cars from the teens, 20’s, 30’s, 40’s, and 50’s primarily had nearly nothing that we have today in terms of safety!  Seismic retrofitting has been on a similar evolutionary journey, with the latest technology offering the most benefit.

It is most often true that the older the home, the more it will benefit from seismic retrofitting.  The only real reason to have house bolting done to a house is to prepare it for an earthquake; no earthquake, no house bolting needed. No car wreck, no safety features needed…  Though it is a personal decision, most people realize that just as driving around without contemporary safety features is not ideal, neither is hoping that their house is able to withstand the forces of Mother Nature should the time ever come.

Bad Foundation BoltTRUE: All legally permitted houses built after 1936 in the City of Los Angeles and most surrounding cities are “bolted” to their foundations.

FALSE:  Those bolts are in the same condition now as they were when installed…

Having crawled under 1,000’s of houses and seeing many interesting sights during those “adventures”, above is a photo of something that we see all too often. This is one of a series of failed anchor bolts in a “bolted” house built in the late 1930’s.

There are several key points in the photo. First, and most obvious, the rusted anchor bolt was removed by simply lifting it out of the piece of wood that was originally anchoring it down to the foundation. No tools required, it just came right out. Secondly, notice the chunks of concrete lying in the dirt below. This is the cracked foundation created by the expansive pressure of the rusting metal over time. Why? Water coming through from the exterior over time.  Next you’ll notice the white chalkiness on the concrete, this is the mineral deposits that water has pulled out of the concrete foundation, further weakening it.  On the ground you can see the metal shards that once formed a perfectly good steel anchor bolt.

If you’re not sure of the status of what’s holding your house down, we can come out and perform a fast, honest, and accurate evaluation of your foundation system and can tailor a prescription to bring your home up to current standards seismically.