Why FEMA P-1100-2A Is Better Than Plan Set A

Why FEMA P-1100-2A Is Better Than Plan Set A

 

Just in California alone, as many as 1.2 million houses are at risk from earthquakes due to their construction.

 

This threat isn’t something that “might” happen, either. It will happen. It’s just a matter of when. There’s even a US Geological Survey estimation that there’s a 72% of a magnitude 6.7+ earthquake hitting the Bay Area by 2043.

 

Because of this, homeowners in the area are encouraged to retrofit these homes to resist earthquakes better. Commonly, these are a standard Plan Set A and a FEMA P-1100-2A plan set.

 

Both have their pros and cons. However, we believe the FEMA P-1100-2A is a far better choice for those living in California.

Prefer video?
Watch: “Which Standard Applies: Plan Set A, FEMA P 1100, or Engineering?”

In this short video, we walk through when Plan Set A is allowed, when FEMA P‑1100‑2A is better, and when you need full site‑specific engineering.

What is FEMA P-1100-2A?

FEMA P-1100-2A is a prescriptive earthquake retrofit plan set for crawlspace (cripple walls) dwellings. It was published back in October 2019 as part of the FEMA P-1100 report.

 

The full FEMA P-1100 document was developed for the Federal Emergency Management Agency and the California Earthquake Authority. It was designed to address known seismic weaknesses in typical wood-frame houses.

 

Volume 2A of this report is a “Plan Set for Crawlspace Dwellings”. Therefore, it provides pre-engineered retrofit drawings and specifications that contractors can use to strengthen a house’s crawlspace without needing a custom-engineered design.

When FEMA P-1100-2A Applies

You should consider using FEMA P-1100-2A in the following situations:

 

• Cripple Wall Height Exceeds 4 Feet: A FEMA P-1100-2A permits cripple walls up to 7 feet in height.
• Steeped or Sloping Foundations: This plan is allowed to be used on sites with a downhill slope up to 20% grade.
• Irregular Configurations Within Limits: The FEMA P-1100-2A has more detailed provisions that may handle certain “non-standard” conditions better than Plan Set A.
• Heavier or Larger Structures: The plan allows for much heavier loads than the Plan Set A without an engineered design.
• Voluntary Upgrade When Plan Set A is Allowed: Even if your house meets Plan Set A criteria, FEMA P-1100-2A could be looked at as an “additional” upgrade, as it is more thorough.

What is Plan Set A?

Plan Set A is an older prescriptive seismic retrofit guideline for wood-frame homes with crawlspaces. It serves as a “standard” template to strengthen older homes without requiring a custom-engineered design, allowing for a lower-cost retrofit.

 

Originally dating back to 2006, and amended once in 2008, Plan Set A was developed in California for “bolt and brace” type retrofits (10 years before the creation of the program) of pre-1979 homes. Therefore, it involves adding foundation anchor bolts, plywood shear wall panels on crippled walls, and framing connections, similar to the FEMA P-1100-2A, but with limited applicability.

When Plan Set A Applies

You should only use Plan Set A if all of its eligibility conditions are satisfied and if a basic brace and bolt retrofit is deemed sufficient for your home.

 

Therefore, it applies to one or two-story wood-framed houses with a continuous perimeter foundation, no cripple walls taller than 4 feet, no excessive weight, and generally regular geometry on a site level.

 

If you’d rather watch a walkthrough, here’s the video version of this topic:
https://www.youtube.com/watch?v=8yOgG89LuDs&list=PL9JsaMeNvYbAYWmldr67s_q7-RVWcB4EC&index=10

FEMA P-1100-2A vs. Plan Set A

Category	FEMA P-1100-2A	Plan Set A
Cripple Wall Height	Up to 7 ft	4 ft max
Ceiling Height	Max 9 ft anywhere in home	Not specified
Home Types	Broader range, some irregularities allowed	Simple, regular homes only
Sloped Sites	Up to 20% grade	Flat/ low-slope only
Detailing	Stronger: hold-downs, modern specs	Basic bracing and bolting
Hardware	Code-approved, clearly specified	Often misused or underspecified
Upgrade Path	Compatible with future improvements	No structured upgrade path
Use Case	When Plan Set A doesn’t apply or by choice	Only if strict criteria are met
Performance	Higher resilience, fewer failure risks	Improves life safety, but more limited

Why FEMA P-1100-2A Is Better

You can probably see this for yourself. However, the FEMA P-1100-2A is a much better choice when compared with the Plan Set A.

 

Just to clearly outline it, this is because it:

 

• Covers More Home Types: Works on a broader range of homes, including those on sloped sites or irregular layouts.
• Works for Taller Cripple Walls: Allows retrofitting of crawlspaces with cripple walls up to 7 feet tall.
• Stronger Seismic Detailing: Uses more hardware, tighter nailing patterns, and modern engineering specs.
• Fewer Failure Risks: Reduces known weak points and failure modes seen in older or poor retrofits.
• Better Upgrade Path: Aligns better with modern FEMA standards and is easier to build on for future seismic improvements.

Why Neither Option Makes Your Home “Earthquake Proof”

Something we want to make very clear is that neither the FEMA P-1100-2A nor the Plan Set A will make your home “Earthquake Proof”.

 

Unfortunately, there’s a huge misconception regarding this. Sometimes, this is even spread by contractors. However, regardless of the seismic retrofit you choose, your house can still be damaged by earthquake activity.

 

What these retrofits do is greatly reduce the chances of collapse or major structural failure. Therefore, they’re used to protect lives and prevent fatal events. This doesn’t mean, though, that your house won’t be damaged one way or another.

 

In fact, California’s building code for retrofit explicitly states this. They say that their standards “will not necessarily prevent earthquake damage”. The goal is to improve performance, not guarantee an immortal building.

When You Should Consider Engineered Plans or FEMA P-58

FEMA P-1100-2A is excellent for most homes. However, sometimes, you’ll need a custom-engineered solution or a performance-based FEMA P-58 analysis.

 

This can happen when:

 

• Your home doesn’t qualify: If your house has crippled walls over 7 ft, more than two stories, steep slopes, or an irregular layout, you’ll need engineered plans.
• You want better performance: FEMA P-58 can model expected damage, repair, cost, and downtime, allowing for upgrades that go beyond life safety.
• You have a high-value or critical-use home: If you can’t afford long downtime, an engineered retrofit can deliver stronger protection.
• It’s required by code: Some homes fall under mandatory retrofit rules that require an engineered solution.

How Avant-Garde Approaches Seismic Retrofits

Our approach for Bay Area home retrofit is built on professionalism, knowledge, and home safety. Here’s how we do things differently to maximize the effectiveness of your seismic retrofit:

Thorough Assessments by an Expert

We believe an expert should evaluate every home’s earthquake vulnerability before deciding on a retrofit.

 

That’s why we focus on professional, hands‑on assessments, not quick drive‑by estimates. Each project is assigned to a senior field technician with over 10 years of experience evaluating Bay Area crawl spaces, foundations, and cripple wall framing.

 

After the site visit, all findings, photos, and recommendations are personally reviewed by Matthew, whose family has over 35 years of seismic retrofit experience in the Bay Area.

 

Based on that combined experience, we then provide clear, professional advice on the retrofit approach best suited to your home and your risk tolerance, from minimum program work to more complete protection.

Code-Compliant, Site-Specific Solutions

All of our retrofits are code-compliant and tailored to your site and home. This guarantees that your property meets the safety requirements set by the applicable California Building Code.

 

It doesn’t matter if you go with a standard Plan Set A, FEMA P-1100-2A, or a custom approach; all retrofits will meet the applicable code requirements set by the state.

Use of Advanced FEMA Standards

We stay on top of seismic retrofit standards, which means learning and utilizing the latest FEMA standards in our projects. This allows us to give you the best possible safety based on your requirements.

Correct Hardware and Detailing Every Time

Our team obsesses with using the correct hardware and detailing as well. Everything we use is the proper grade and installed in the correct manner.

 

This goes for everything also. From the bolts to the nail spacing and pattern, all the way to the foundation plates. Everything is used and installed as intended with extreme precision.

Transparent Guidance for Homeowners

We understand that seismic retrofits are a challenging topic. It’s not something many people understand or are experts in.

 

Therefore, we’re completely transparent with our client. We’ll discuss your choices in layman’s terms so you have realistic expectations regarding the project.

 

Everything will be outlined simply. You’ll know exactly what you can and can’t do, as well as understand why we recommend specific installations or plans.

Conclusion

Choosing the right seismic retrofit solution for your home is massively important.

 

Just so you know, FEMA P-1100-2A is the preferred choice when compared to Plan Set A. It will outperform Plan Set A every time.

 

However, if you want to take this a step further, getting a customized engineered plan is best. You can then get upgrades that meet performance goals.

 

If you’re unsure about what’s best, feel free to contact us at Avant-Garde.

 

Our professional retrofitters will be more than happy to guide you to the best option for your situation.