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

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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 is 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

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Latest News

The Differences between Ordinary Moment Frames and Special Moment Frames

Due to the latest seismic ordinances passed in Santa Monica, there has been a lot of talk around different seismic solutions and options, moment frames being one of those options.  There are three different types of moment frames: ordinary, intermediate, and special. After reading this short article, it will only take a moment for you to understand the fundamental differences between Ordinary Moment Frames and Special Moment Frames.

Seismic Retrofit building structure

Ordinary Moment Frame- Seismic Retrofit

To begin, a standard moment frame is defined as a system of columns and beams which are connected by either fully or partially restrained moment connections.  As one might expect based on its name, “ordinary” moment frames, one of the three types of moment frames,  are generally found in areas described as non/low-seismic regions. The expectation is that ordinary moment frames are able to endure limited inelastic deformations caused by lateral forces. Ordinary moment frames only require onsite welding, which differs from the requirements for special moment frames. Special Moment Frames, another type of moment frame, are “special” in that they are expected to endure more significant inelastic deformation than ordinary moment frames. In addition, Special Moment Frames utilize different connections than Ordinary Moment Frames and they do not require field welding. Generally even with on-site welding the cost of Ordinary Moment Frames won’t go over that of a Special Moment Frame. These connections must be prequalified, as stipulated by the American Institute of Steel Construction.

Since Special Moment Frames can endure more deformation, they are often found in areas described as mid to high-seismic regions. Seismic retrofits constructed utilizing moment frames can sometimes be more costly and time consuming because moment frames often require more welding on site than other frames do. Traditionally, special moment frames are more expensive than ordinary moment frames because these types of frames are often found in mid/high-seismic regions. Your engineer may decide whether or not moment frames are right for your particular project but they are preferred under certain circumstances. If your building includes large open areas within your structure, such as a tuck-under parking garage, moment frames would often be the building solution that is preferred.  Considering the latest ordinances regarding soft story seismic retrofits, the Santa Monica area will be seeing moment frames of all types over the course of the next five years.

Seismic Retrofit Structure to decrease earthquake damage

Photo courtesy of Hardy Frame by MiTek

For more helpful information on seismic retrofit services that will fit your individual projects needs, keep an eye out for more blog postings on our website-

References inlcude: (by Dylan Richard and Walter Moore) 

August 4, 2017

Recent Recorded California Earthquakes

Written: Thursday May 18th at 10:37 AM

Within the past 24 hours there have been seven earthquakes in Southern California, each of which with a magnitude of 2.2 or below ( Although earthquakes of this magnitude are not even considered “minor” on the Richter scale and are generally not felt, their occurrences and closeness to one another are unsettling nonetheless. The last 30 Days has seen 190 earthquakes in the last thirty days in Southern California, the largest of which actually occurred less than 48 hours ago. Isla Vista experienced a “slight” 4.1 magnitude quake at 9:42 pm, though no reports of damage were reported.  While earthquakes of a relatively small magnitude do not literally “shake” us and therefore may be easy to ignore, it is important to remember that at one point or another, an earthquake of larger magnitude will occur; it is just a matter of when.

For years, there has been extensive discussion about when “the big” earthquake will hit. It has been suggested that Southern California is “overdue” for a big earthquake, which could hit at any time. Although many people would prefer to simply ignore Southern California’s precarious position in relation to the San Andreas Fault. According to the San Andreas Fault website, “the big one”, although “hypothetical”,  is expected to have a magnitude of 8 or greater. Proper steps must be taken to ensure that the negative impacts of this earthquake are as minimal as possible. This is of particular importance in urban areas, due to larger populations and the types of buildings found in these particular places. It is evident that there has been a greater awareness of the threat of these quakes when considering the recent mandatory seismic retrofit ordinances that have been passed in Southern California as well as other areas of California. The recent discourse around the somewhat small but frequent earthquakes that have been occurring, in addition to the imminent threat of a much larger one, has led to a greater understanding the need and importance of seismic retrofitting. The implementation of mandatory seismic retrofit ordinances for possibly vulnerable buildings will benefit and serve thousands of buildings, but most importantly save the lives of those who live in buildings that may be severely impacted by a large and devastating earthquake.



August 4, 2017

Seismic Retrofit Pass Through Rate City By City

It can be a misconception that if you own a rental property you are extremely wealthy with millions in liquid capital. Some may picture Daddy Warbucks or Scrooge McDuck counting his gold pieces in a vault. However in reality, many multi-family property owners in California only own the one building. Many of the buildings have been passed on by inheritance or death of a spouse. Others use that piece of property as their only source of retired income.  Many of the property owners affected by the soft-story retrofit ordinance may not have the money in the bank to pay for the retrofit work and that must be addressed.

In order to assist property owners with some of the costs that are associated with the seismic retrofitting of their buildings, “pass through programs” have been implemented in certain cities. A pass through program is essentially a way that the burden of cost can be lessened for property owners. Based on the type and size of the building as well as what reinforcement it requires, the cost of a retrofit can vary considerably. For example, a 4 unit 3 story building on Haight Street in San Francisco costs $120,000 to retrofit but a 6 unit 3 story building on Dolores Street costs less than half the price of the aforementioned building ( Regardless if the price is $200,000 or $20,000, it is still an expense that many property owners are not able to incur alone.

The pass through program seeks to provide relief to property owners, many of whom rely on their building as a sole source of income. So far San Francisco seems to offer the highest pass through rate, allowing tenants to pass through 100% of the cost to tenants. However, this pass through cannot happen overnight. There are limits on how much property owners can increase the rent per year. In San Francisco that limit is no greater than $30 a month or a 10% increase of the tenant’s existing rent (

Los Angeles does not have as hefty as a pass through rate as San Francisco does. The maximum pass through rate in Los Angeles is 50%, which must apply to all rental units in the building. This can be implemented through a rent increase of $38 per month for 120 months, according to the Los Angeles Housing and Community Investment Department (

Santa Monica and West Hollywood have not yet established a pass through program. West Hollywood City Council has stated that they will consider potential pass through options in the coming months (

We (and your city council members) understand that the mandatory retrofitting of buildings puts a significant financial strain on building owners. This is why pass through programs and other financing options are available. Collectively, building owners and tenants will make themselves and their homes safer through seismic retrofitting- the importance of which cannot be priced.

In the end, whether the property owner chooses to pass costs through or not, one thing that landlords and tenants can agree on is that the retrofit work is a necessary action to protect the building structure, personal property and many lives from major loss.

References include:


August 3, 2017