Seismic Retrofit Services

Penhall Retrofit Plans for Seismic Retrofit, Soft Story Seismic Retrofit

Penhall is your top choice for seismic engineering and construction services for every type of seismic retrofitting. Penhall Company is celebrating 60 years of excellent service! Whatever your design build need we are ready assist you with your next seismic retrofitting project.

Penhall has a long history of seismic work. While we possess the resources and capabilities to take on any size contract, we consider no job too specialized, too large or too small. We believe that every project deserves our utmost attention to detail and commitment to client satisfaction. Our clients know they can depend on us to get the job done on time and on target, from start to finish and every step in between. Whatever your needs, wherever you’re located, trust Penhall Seismic retrofit services do it right.

Seismic Retrofitting Service at Penhalll

Buildings at Risk from Seismic Events

Soft Story

Currently in California the most common type of seismic retrofitting is called soft-story retrofit.  The weak wood frames are often seen in multifamily apartment dwellings with tuck under parking.  This style of  building is a common design in both San Francisco and Los Angeles. Due to multiple seismic retrofit ordinances in the State of California cities like San Francisco and Los Angeles have already begun engineering and construction to become compliant. Other cities are following suit like Santa Monica and West Hollywood.  We expect many more cities to jump in line to become compliant with new seismic safety standards.   Common solutions for soft-story retrofitting are steel special moment frames, cantilevered column solutions, or shear wall paneling.

Non-Ductile Concrete

Another type of seismic retrofitting includes non-ductile concrete buildings. Often seen in multi-story buildings built pre 1978 before seismic codes were tightened. The buildings are considered reinforced concrete in design, but  often don’t have enough steel reinforcement to handle a major seismic event. While there are several combinations of solutions for non-ductile concrete steel beam installations and polymer fiber wrap solutions are often used to retrofit non-ductile concrete buildings.

Unreinforced Masonry (URM)

URM construction is another type of seismic retrofit that Santa Monica is most recently preparing for. This type of construction often seen on older historic buildings has no metal or steel reinforcements at all and is literally often only brick and mortar. A common solution it to center core or drill through the bricks vertically and thread rebar or steel through and pour back concrete to secure hole.

Penhall launched operations nearly 60 years ago supporting southern California with a singular commitment to providing the highest level of services to its clients. Since then, Penhall has expanded its reach, scope and expertise, serving clients across the U.S. and beyond. Today, Penhall encompasses 41 strategic locations and employs more than 1,200 professionals, with current and ongoing expansion into Canada. We’ve dedicated that last 60 years to honing our specialized seismic, scanning and concrete services.

Common Soft Story Retrofit Solutions

What are moment frames?

  • A moment frame is a system of columns and beams that are connected to one another with fully and/or partially restrained connections.
  • A special moment frame is expected to withstand significant inelastic deformation as a result of lateral forces. They are used typically in mid/high-seismic regions and are significantly more expensive than other retrofit options.

What are cantilever columns?

  • A cantilever is a horizontal beam that is unsupported at its end.
  • A cantilever column is the vertical component that supports the horizontal cantilever beams.

What are shear walls?

  • A shear wall is a vertical-oriented wide beam that transfers lateral forces from exterior walls, floors, and roofs to the ground foundation.
    vertical-oriented wide beam also known as a sheer wall

What is destructive testing?

  • Destructive testing is the process of determining design weaknesses.
  • For seismic retrofit projects, the city would like to see the quality and connections of load-bearing beams that are at-risk of failure in the event of an earthquake prior to approving permitting for the project.
  • This type of testing requires exposure of these connections.

ZOOMED IN Destructive testing area to determine design weaknesses. ZOOMED OUT Destructive testing area

What is non-destructive testing?

  • Non-destructive testing is the process of evaluating materials or components for discontinuities or differences in characteristics without causing damage to the structure.
  • Ground penetrating radar uses radio waves to scan concrete.
  • Concrete x-ray uses x-rays or gamma rays to image the interior of a concrete target to identify embedded objects.

Ground penetrating radar being used to locate imbedded hazards GPR Analyst Scanning a concrete slab to locate post tension cable

Latest News

50,000+ Readers reading a feature article on soft story seismic retrofitting

Penhall Company Seismic Services Division is happy to share a contribution to the AOA Magazine March Edition.

Check out a feature article in the March issue of the Apartment Owners Association of California authored by Director of Seismic Services Elizabeth Wilson.

Excerpt from the article: Soft-story retrofits: The costs, concerns and construction.

“California is the golden state that enjoys beautiful weather, gorgeous beaches and a bit of a seismic activity complex. Californians wake up all too often to read shocking headlines about earthquake swarms, mega-quakes and inevitable devastation. Given the state’s seismic history and the many scientific studies released over the last three years, it is no big surprise that city agencies have started to focus on loss mitigation by way of regulation. Cities all over the state are taking action in preparation for the next big shake-up….”

Full magazine article can be viewed by clicking on the pages below or at the AOA website by clicking here.

Front Cover of AOA Magazine March

March Edition-Soft Story Retrofits Page 54


Page 56 Magazine March Edition Soft Story Retrofits

Page 57 Magazine March Edition Soft Story Retrofits


March 1, 2017

Soft-story retrofit: The cost, concerns and construction

California is the golden state that enjoys beautiful weather, gorgeous beaches and a bit of a seismic activity complex. Californians wake up all too often to read shocking headlines about earthquake swarms, mega-quakes and inevitable devastation.  Given the state’s seismic history and the many scientific studies released over the last 3 years it is no big surprise that city agencies have started to focus on loss mitigation by way of regulation.

Cities all over the state are taking action in preparation for the next big shake-up. For example, San Francisco launched a mandatory soft-story retrofit program in 2013 and Los Angeles followed more recently in late 2015.

So the problem was identified and the regulation is put in place, but what next? Property owners of the over 18,000 soft-story buildings in Northern and Southern California are left with loads of questions and concerns.

The biggest question is How much will it cost to retrofit my building?  3 years ago the answer to that question was much more ambiguous, but thanks to San Francisco’s Department of Building and Inspection,  data was released that will shed some light on costs for those still waiting to retrofit.

According to about 7 million dollars in construction costs for retrofits are already completed and with that data comes some helpful averages from San Francisco’s current construction boom.

For multi-family dwelling properties up to 8 units, the average construction cost was $63,500. Total construction costs for all buildings up to 8 units are reported to date as $2,349,470.00.

Owners of 9-18 unit buildings paid an average of $76,875. Total construction costs for all buildings 9-18 units are reported to date as $3,843,715.00.

Lastly buildings with 19 or more units paid an average of $96,140 per retrofit. The total cost of construction for 19+ unit buildings was reported to date as $673,000.

In looking at the market in Southern California, residents of Los Angeles can probably expect to pay 20% less than the San Francisco average comparatively due to less complicated topography and some other deciding factors. Looking at the San Francisco cost data you can see some major cost discrepancies from one property to another. For example, their averages may be a little higher due to ADU (Additional Dwellings Units) added on some properties.  The public information and full data table including street name of San Francisco retrofit costs can be found at

After costs often the next concern is “How do I choose a reliable and reputable engineer and contractor”? This is an age old question that has been around since the inception of the infamous general contractor. We have all heard stories of the “fly by night” vendor looking for a quick buck and one way ticket out of town.

In San Francisco there have been many reports by both retrofit customers and at the city level of price gouging and even over-engineering by some firms. Here are a few tips as you research vendors to ensure you choose the right servicer. First, it is always good to get 3 quotes.  When comparing rates make sure what your inclusions and exclusions are before comparing “apples to apples”. Second, it is important to do your homework.  Ask questions of your contractor that are more detailed i.e. Do you have an in-house engineer or do you outsource? Do you value-engineer for the lowest construction cost, but most compliant solution? How many years have you been in business? What is your CA license #? Often a savvy customer can scare away the wrong kind of vendor.

In the end no one knows when the next big earthquake will hit. While property owners don’t have a crystal ball to tell them the future, they can take proper steps now to protect their tenants and buildings from catastrophe by doing their research and choosing a reliable and licensed contractor. Of course then when the work is done they can get back to enjoying California’s sunshine and sunsets.

January 4, 2017

Seismic Retrofitting isn’t just for Californians anymore-Portland Oregon starts the road to retrofitting.

As many southern and bay area Californians have recently experienced seismic retrofitting is a part of a new reality. Many structures that lack the support needed to withstand a major earthquake including both soft story and non-ductile concrete buildings are vulnerable to next “big one”. A 7.0 or higher is generally believed to be imminent, but when it will hit nobody knows. With seismic activity being not a matter of if, but when, other cities are evaluating their structures for strength against earthquakes.  Portland, Oregon is one of the latest cities to attempt to jump on board the seismic retrofitting bandwagon. The city has acknowledged 1,700 unreinforced masonry buildings (blocks without rebar reinforcement) that need to get up  to speed on seismic safety and compliance issues fast.  Read more about Portland, Oregon’s road to retrofitting.

October 27, 2016

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