If you would like to know more about the brand new state-of-the-art seismic retrofit guideline, there are around 30 educational videos and web pages that you will find interesting. Just type ICC 1300 in the search box in the upper right.

Why ICC 1300 Stem Wall Retrofits Cost Twice As Much As Standard Plan A.

How much does a retrofit cost?

How Much Does a Seismic Retrofit Cost?

The calculations in this video are the basis of Standard Plan A and are 15 years old.  Advances in the understanding of Bay Area potential earthquake magnitudes have changed.  These more up-to-date anticipated force levels are the basis of ICC 1300 Vulnerability Based Seismic Assessment and Retrofit of One and Two-Story Dwellings and are significantly higher than the force level behind Standard Plan A. As a consequence, far more retrofit components are required which increases the seismic retrofit cost.   If you want the retrofit to work as intended and be certain your house will be saved from catastrophic damage, using these higher force levels is advised.  The video below illustrates the impact of these higher force levels on the cost of a seismic retrofit and the number of components required by Standard Plan A compared to ICC 1300

There are other guidelines that you can use, or you can design your retrofit yourself. So long as you understand basic engineering there is no reason why you can’t do a great job.  You can rent all the tools at the local tool rental yard and buy the materials at any builder’s supply.  Homeowners often do the best work because no one cares about their home more than they do.

I think doing something between Stanard Plan A and the seismic retrofit guideline ICC 1300 Vulnerability Based Seismic Assessment and Retrofit of One and Two-Story Dwellings might be the best choice.  Once you have all the materials and tools on hand it is not that much extra work to make a Standard Plan A retrofit 25% stronger.

Again, if you want to be sure your retrofit will perform as intended your retrofit should be designed around these higher force levels if you can afford it.

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