Common Seismic Building Code Violations in the Bay Area

In a high seismic activity region like the Bay Area, specific seismic building codes have been created to ensure the safety of people and property in such events.

When these codes aren’t met, however, a property is deemed unsafe. That’s why it’s important to know the most common code violations to ensure your building is safe and prepared.

What Are Seismic Building Codes?

Seismic building codes are legally enforceable standards to ensure buildings can withstand local seismic activity. They’re used in earthquake-prone regions, like the San Francisco Bay Area, to guarantee public safety, structural integrity, and property preservation.

How Is a Seismic Building Code Violated?

The most common reasons seismic building codes are violated are through overlooked work, outdated structure, or contractor shortcuts.

For example, in the Bay Area, we often see unpermitted or DIY renovations that bypass code review or older buildings that were never retrofitted.

Another way a code is violated is through contractors or construction errors. Perhaps an anchor bolt hole has been drilled oversized, the wrong size bolts have been used, or not enough bolts have been installed, etc.

Alongside the above, sometimes, codes just naturally get violated. A code might get updated, and the latest retrofit may no longer be adequate. 

Most Common Seismic Building Code Violations

There are many common seismic building code violations. We believe that these are:

1. Missing or Improper Foundation Bolting
2. Unbraced Cripple Walls
3. Unaddressed Soft-Story Conditions
4. Lack of Shear Transfer Connections
5. Non-Ductile Concrete Frames

1.   Missing or Improper Foundation Bolting

The California building code requires sill plates (also known as mud sills) to be anchored to the foundation with steel bolts with bearing plates and nuts—with at least two exposed threads above the nuts.

Alongside this, there should be two per sill section (one near each end), and they shouldn’t be spaced more than 6 feet on center. At shear walls, the spacing is required at 32”. Bolts are also required at each end of the mudsill, and centered at the first and last bay of each shear panel.

In many older homes, think homes built before the 1950s, there may be no anchor bolts at all. In certain Bay Area cities, like San Francisco, though, 44% of homes have been built before 1940.

Not only this, but some contractors install foundation bolting incorrectly. Some may space them incorrectly, use the wrong type or embedment, install too few, or drill the holes too large, reducing the strength and integrity of the bolts and overall retrofit.

This code violation is massively problematic. Without proper foundation bolting, it can cause the house to slide off its foundation during seismic activity.

2.   Unbraced Cripple Walls

Cripple walls are short wood-framed walls above the foundation on a raised floor. They’re there to increase the lateral strength of your property’s foundation/first floor.

The code (CBC) and retrofit guides require these walls to be sheathed with structural-grade plywood panels. They should also be tied to the framing.

Missing framing or plywood, however, means little cripple wall strength. This makes it extremely vulnerable during heavy earthquakes.

Most cripple walls lack plywood altogether, which is more common than you think, leaving them unbraced and weak.

In South Napa, this was a huge issue in 2014. A lot of the home were built before pre-1980s with inadequate cripple wall bracing, leading to many homes getting “red flagged” for structural failure.

When shear panels are installed, they must be properly framed, nailed, notched, spaced, sized, etc.. If any of these components are done incorrectly, which usually is the case, you will not have the required protection.

3.   Soft-Story Conditions

A soft-story appears when the ground floor has an opening (garage door, large storefront window, etc.) spanning most of the property’s width with minimal shear walls. This, unfortunately, makes the first story remarkably weak compared to those above.

In the Bay Area, however, a large majority of apartment buildings and condos built before 1978 have soft stories. These, due to the time they were developed, don’t meet the modern seismic standard imposed by the state.

Currently, the SF Mandatory Soft-Story Retrofit Program is doing a great job of identifying these buildings in their area. Still, many continue to violate this building code.

Violating this means that the building has inadequate lateral resistance. In circumstances like a seismic earthquake, properties with poor soft-story conditions usually pancake or collapse.

4.   Lack of Shear Transfer Connections

Local codes state that shear transfer ties/clips or blocking are required to tie the floor framing (joists/plates) to the braced wall or mudsill. With many Bay Area homes, though, this is usually overlooked.

What we often see is the contractor using the toe-nail connection per legacy framing standards. This states that you must nail three toe-nails per joist. However, this is generally the only connection; no metal connectors are installed, making it non-compliant.

Without this connection, especially with older homes, the floor can move off the braced wall during a quake. If this happens, the structural integrity of the property can be at risk.

Further, many modern retrofits often install the wrong type of connector, or leave fasteners missing and/ or not installed properly (most people use nails even though they know structural screws offer more strength, higher withdrawal rating, and have a lower chance to split the wood).

5.   Non-Ductile Concrete Frames

Many of the Bay Area commercial buildings and even older apartments were constructed pre-1970. During this time, they used reinforced concrete frames. Though great for the time, now, these are considered to have a lack of rebar details (aka non-ductile concrete).

In a non-ductile building, columns don’t have closely spaced ties. As a result, instead of flexing during seismic activity, they shatter. This can cause the overall strength and loading of the building to be imbalanced.

All of these structures are also considered non-compliant. Yet, despite this, thousands remain in areas like San Francisco and Oakland. In fact, there are around 4,000 older concrete buildings in San Francisco alone.

How to Ensure Seismic Building Code Compliance

To bring an existing building into compliance, Bay Area owners should follow the clear retrofit process below:

1.   Schedule a Professional Seismic Evaluation

Before anything, hire a licensed professional (preferably someone experienced in seismic retrofits) to take their time properly evaluating your property.

During this evaluation, they’ll thoroughly evaluate the entire crawl space and foundation plus reviewing any past retrofits. While most retrofits start in the crawl space, creating a continuous load path starting at the roof and transferring all the way down to the foundation is the only way to obtain the best level of protection.

 You will find most contractors bending over backwards to give you a “free estimate.” For most homeowners, their home is the largest investment they will make, and your family spends at least 33% of their time home (assuming you sleep at least 8 hours a night every day at home).
When it comes to seismic protection for your home, and more importantly your family, you should not be looking for the cheapest or least amount of work done possible. You should instead look for contractors that actually have knowledge performing entire home retrofits, contractors that can thoroughly explain how an earthquake force can affect your home, and how your home may react during a strong seismic event.

There are specialty licenses for almost everything in construction, and yet, sadly, there is none for seismic retrofitting.

2.   Review Local Requirements

In the Bay Area, building codes can vary by city. Therefore, after the evaluation, your seismic retrofit professional will guide you through any city-specific seismic requirements or ordinances.

Currently, there are several programs to understand. This is the San Francisco Soft-Story Retrofit Program, as well as the Oakland and Berkeley Ordinances.

The seismic retrofit professional you choose should confirm whether or not your property is subject to these new mandatory retrofit rules.

3.   Obtain Retrofit Designs

Once the assessment is complete, your contractor or engineer will prepare a detailed set of retrofit drawings and specifications. These will specify the scope of work.

All of the plans should align with the California Building Code (CBC), California Residential Code (CRC), Chapter A3, Plan Set A, and/ or FEMA recommendations like FEMA P-1100, FEMA P-1100-2A, or FEMA P-1100-2B.

4.   Hire a Licensed Contractor

Your next step is to hire a licensed contractor to carry out the work. A lot of the time, the retrofit designer will recommend someone or have a team that can carry out the work.

As a rule of thumb, you want to look for contractors that:

• Have experience with seismic retrofitting before the creation of grant programs like the Earthquake Brace + Bolt (EBB).
• Are familiar with seismic codes on a regional and city level.
• Actually have knowledge beyond the minimum requirements of Plan Set A (most contractors cannot even follow these two-page requirements properly).

Ideally, you want to avoid hiring general contractors with zero seismic retrofit experience and/ or cannot offer any recommendations for increased seismic protection.

5.   Get Permits and Inspections

Once you have your retrofit plans, your contractor should apply for a building permit through the local building department. A city inspector will then verify the plans as well as perform on-site visits as the work is being carried out. Although the inspections should catch all non-complaint work, this often is not actually the case. Not only are the inspectors not given the proper amount of time to inspect, the plans are often missing key requirements, and the work is for the most part considered to be “just a voluntary seismic upgrade.” As long as the work does not actually make your home any worse, they often will approve anything. In some cases, we have seen seismic retrofits done so incorrectly that they actually did make the home more dangerous (and was still approved by the local building department, EBB, and FEMA).

Additionally, when a seismic retrofit is done incorrectly, but the homeowner does not know, they will have a false sense of security which ultimately may be a more dangerous situation than knowing your home is not safe.

6.   Apply for Grants or Rebates

If you do not need to pay out of your own pocket, why do it? Before any work commences, look for grant programs that help property owners fund their seismic upgrades.

Nowadays, there are quite a few. Some popular options include:

• Earthquake Brace + Bolt (EBB): Offers up to $3,000 for foundation bolting and cripple wall bracing.
• Soft-Story Retrofit Grant: Provides up to $13,000 for eligible soft-story seismic retrofits.
• Low-Income Retrofit Assistance: Qualifying households may receive up to $5,800-$10,000 cost coverage through the EBB Supplemental Grant.

Ideally, your contractor will know what grants you can apply for.

7.   Keep Documentation

When your retrofit is complete, keep records of everything. This includes stamped plans and valuations, permit applications, documented photos, invoice, etc. This will be essential for possible insurance claims, resale, or refinancing.

Contact Us

Our team at Avant-Garde are experts in seismic evaluation, retrofit design, and retrofit installation in the Bay Area.

It doesn’t matter whether you are concerned about a retrofit in San Francisco, a soft-story retrofit in Oakland, or foundation bolting; we’re here to help every step of the way.

To get a better understanding of how our team can help, contact us today . Waiting will be a professional ready to assist.