Homeowners usually retrofit because they decide to. Owners of commercial buildings usually retrofit because someone tells them to: a city letter, a lender's report, or a buyer's due diligence. That difference matters more than it sounds, because whoever is doing the telling also sets the deadline, the minimum scope of work, and whether there's any option besides construction.
Quick answers
- Three things usually force a commercial retrofit: a local ordinance, a lender or buyer's seismic risk (PML) report, or a renovation or insurer that brings the structure under review.
- The trigger shapes the job. An ordinance sets a deadline and a minimum standard; a lender sets a loss number to get under; a voluntary project lets you choose the goal.
- The buildings most often flagged are unreinforced masonry, older concrete, older tilt-ups, soft-story wood frames, and pre-1994 welded steel frames.
- Start with a structural engineer's evaluation, then bring in a licensed contractor to build what the engineer designs.
- For apartment buildings with tuck-under parking, see our soft story retrofit guide, which covers that program in detail.
Which commercial buildings get flagged most often
The same handful of building types show up again and again, on ordinance lists and in lender reports alike. One seismic retrofit firm summarizes the common weak points: unreinforced masonry buildings "make up many of the older structures typical in downtown communities," and "many tilt-up structures built prior to the late 1970s were built with limited or weak connections that have been proven to fail in an earthquake." Older non-ductile concrete buildings and soft-story wood buildings with open ground floors are the other two familiar categories; the soft-story type has its own guide.
Steel is not automatically safe either. After the 1994 Northridge earthquake, FEMA's policy guide on welded steel frames described damage that "consisted of a brittle fracturing of the steel frames at the welded joints between the beams (horizontal framing members) and columns (vertical framing members)." That is why steel moment frame buildings from before that era appear on some cities' lists alongside the more obvious older types. Our LADBS approved fabricator guide explains how shop-fabricated steel gets accepted on City of Los Angeles permits.
What usually forces the decision
1. A local retrofit ordinance
Some cities require owners of specific building types to evaluate and, if needed, retrofit by a deadline. Santa Monica's program is a good example of how broad these can be: its mandatory retrofit chapter sets priorities that begin with "Priority 1. Unreinforced masonry buildings and concrete tilt-up buildings" and extend to "Priority 4. Non-ductile concrete buildings and steel moment frame buildings," with soft-story buildings in between. If you own an older building in a city with a program, you'll often learn about it through a formal notice. The specific deadlines vary by city and building type, so check your own city's program directly rather than relying on another city's timeline.
2. A lender, buyer, or insurer's seismic risk report
This is the trigger many owners don't see coming. When a commercial property is financed, refinanced, or sold in a seismic region, the lender or buyer often orders a seismic risk assessment, also called a PML (probable maximum loss) report. According to one engineering due-diligence firm, these follow ASTM E2557 and ASTM E2026, and "many lenders use a 20 percent replacement cost benchmark, meaning additional mitigation may be needed if expected losses exceed this level." The same page notes the PML threshold "often determines whether earthquake insurance or seismic retrofits are required during financing or acquisition." The same firm notes the reports typically give two numbers: the SEL (scenario expected loss) and the more conservative SUL (scenario upper loss).
The problem with this trigger is timing. The report usually arrives in the middle of a deal, when there's little room to design and permit structural work. If you expect to refinance or sell an older building in the next few years, it can make sense to commission your own assessment early, so a high number becomes a planning item instead of a surprise that threatens the closing date.
3. Something you're already doing to the building
A major renovation, a change in how the building is used, a new anchor tenant, or an insurer's underwriting review can all bring the structure under closer scrutiny. Whether a particular renovation actually requires structural seismic upgrades depends on its scope and on your local building department's rules, so ask the engineer about it at the design stage, before the renovation budget is locked, not after plans are submitted.
How the trigger changes scope, timing, and options
These three triggers lead to noticeably different projects, and naming yours before you hire anyone saves a lot of wasted design work.
Ordinance-driven work comes with a fixed deadline and a minimum standard written into the program. The Santa Monica chapter quoted above requires owners of listed building types to retrofit if the building doesn't meet the city's standards, so the conversation is about how to meet the standard, not whether to. The main decisions are timing (in our experience, engineers and permit reviewers get busy as deadlines approach) and whether to go beyond the minimum while the building is already open.
Lender- or buyer-driven work is about a number. The goal is to bring the building's estimated loss under whatever threshold the lender uses, which means the engineer can target the specific weaknesses driving the PML rather than retrofitting everything. Because the source above names earthquake insurance and retrofits side by side as possible requirements, some lenders may accept additional coverage instead of, or alongside, construction; that is a lender-by-lender question, so ask it directly before assuming either way. Timing here usually follows the deal, which can mean a compressed schedule.
Voluntary or renovation-driven work gives you the most control. You choose the performance goal with your engineer (for example, protecting occupants versus keeping the building usable after a quake), and you can phase the work around leases and cash flow.
A practical way to use this: when you first call an engineer, say which of the three is driving the project and share any notice or report you already have. It changes what they evaluate and how they scope the design. It also helps to pull together a few things before that first call:
- Any city notice, order, or program letter about the building
- Any PML or seismic risk report from a lender, buyer, or past transaction
- Original drawings or past permit records, if you can find them (they can shorten the evaluation)
- Any earlier structural reports or retrofit work on the building
- A summary of current leases, occupancy, and any renovation you already have planned
None of these are required to get started, but the more the engineer knows about why the project exists and what's already known about the structure, the less of the evaluation budget goes to rediscovering it.
How the process works, at a high level
Most commercial retrofits follow the same broad path. It starts with an evaluation by a structural engineer, commonly using ASCE 41, which the American Society of Civil Engineers describes as a standard that "uses performance-based principles to evaluate and retrofit existing buildings to withstand the effects of earthquakes" through "a three-tiered process for seismic evaluation." If the evaluation finds deficiencies, the engineer designs a retrofit, the design goes through plan check and permitting, and a licensed contractor builds it under inspection. The details of each stage vary a lot by building type, which is why the evaluation, not a generic checklist, should drive the plan.
Keeping the building running during the work
For a commercial owner, construction disruption often worries tenants as much as the retrofit itself. In our experience, the projects that go smoothly plan around the tenants from the start: phasing work floor by floor or bay by bay, scheduling noisy work outside business hours where the budget allows, and giving written notice well ahead of each phase. Before work starts, read what your leases say about access for repairs, construction disruption, and any rent concessions, because those clauses decide what you owe tenants while the work is underway. The lease's work letter plays the same role for build-outs; our guide to warm shell vs cold shell and tenant improvements covers how it splits the work, and our guide to tenant improvement construction covers the process. Residential tenant rules for apartment retrofits are a separate subject covered in our soft story guide.
Who to hire
A commercial retrofit takes two roles. A licensed structural engineer evaluates the building and designs the fix; a licensed contractor builds it. Hire the engineer first, and involve a contractor early enough to comment on constructability and phasing around your tenants. Our guide on how to hire a seismic retrofit contractor covers license checks and what a bid should include. Medici Construction Group is one licensed option for the construction side, holding California A, B and C-10 licenses under CSLB #1114433.
Frequently asked questions
Is seismic retrofitting mandatory for commercial buildings?
It depends on where the building is and what type it is. Some cities require retrofits for specific building types, such as unreinforced masonry, tilt-up, non-ductile concrete, soft-story, and older steel moment frame buildings. Check your own city's program for whether your building is covered and when.
What is a PML report and why does my lender want one?
A PML (probable maximum loss) report, also called a seismic risk assessment, estimates how much damage a building could suffer in an earthquake as a share of its replacement cost. Lenders use it to judge risk; many apply a 20 percent benchmark, and above it may require added earthquake insurance or a retrofit.
Can earthquake insurance replace a retrofit?
Sometimes, for a lender's requirement. Some lenders may accept additional earthquake insurance instead of, or alongside, a retrofit when a PML comes in high. City retrofit ordinances work differently. Santa Monica's, for example, requires covered buildings that fall short of its standards to be structurally retrofitted; check your own city's rules rather than assuming insurance is an alternative.
Does a seismic retrofit lower a building's PML?
It can. A PML estimates expected earthquake loss, so a retrofit that addresses the weaknesses driving that estimate can bring the number down. Ask your engineer to design with the lender's threshold in mind and to confirm how an updated assessment would treat the completed work.
What is a seismic evaluation?
A structural engineer's review of how a building is likely to perform in an earthquake, commonly using the ASCE 41 standard. It identifies deficiencies and is the basis for any retrofit design.
Who pays for a commercial seismic retrofit, the landlord or the tenant?
The lease decides. Review how your leases treat capital improvements and legally required work before the project starts, and get legal advice on any clause that's unclear.
How much does a commercial seismic retrofit cost?
It varies widely with the building type, size, the weaknesses the evaluation finds, and the performance goal. The engineer's evaluation and design are what make a reliable estimate possible, so get those before budgeting.
