Seismic retrofit, explained
Most earthquake damage to older wooden houses is not the building falling down. It is the building sliding off its foundation, or the short walls beneath it collapsing sideways. A seismic retrofit is the work that stops that, and on a typical house it is a few thousand dollars of plywood and bolts rather than a rebuild.
The three pieces of work
California's Earthquake Brace + Bolt programme defines the standard retrofit as up to three upgrades. Between them they address the failure modes that produce the most claims.
- Bolting the frame to the foundation. Anchor bolts or steel foundation plates tie the wooden frame of the house to its concrete foundation. The programme's own summary of why: most earthquake damage occurs when unsecured buildings slide off their foundation.
- Bracing the cripple walls, if you have them. A "cripple wall" is a short wall — four feet or less — between the foundation and the floor of the house, creating the crawl space. It carries the weight of the building. Bracing means sheathing it in plywood or OSB so it cannot rack sideways and let the house topple.
- Strapping the water heater. The cheapest item on the list and a requirement of the programme. An unsecured water heater that tips over breaks its gas and water lines, which is how a shaking event becomes a fire or a flood.
Which retrofit your house needs
It depends on one thing you can check yourself, from the crawl space:
- Brace and bolt — there are short cripple walls between the frame and the foundation. Both bracing and bolting are needed.
- Bolt only — the wood frame sits directly on the foundation (a "stem wall"). Only bolting is needed, and it is the cheaper job.
The work must comply with the California Existing Building Code, Chapter A3, which is written specifically for light wood-frame houses. Approved plan sets that meet Chapter A3 exist, which is what keeps this a permit-and-plywood job rather than an engineering project.
Who is eligible for the California grant
Earthquake Brace + Bolt is run by the California Residential Mitigation Program. The eligibility rule is narrow and specific: wood-framed, pre-1980 homes with a raised foundation. A slab-on-grade house is not eligible, because it has nothing to bolt and no cripple walls to brace.
Registration opens in windows and is offered by ZIP code rather than statewide, so the answer to "can I apply today" depends on the date and your address. The programme runs a notification list for when registration reopens.
What the grants are worth
| Grant | Amount | Who qualifies |
|---|---|---|
| Earthquake Brace + Bolt grant | up to $3,000 | Wood-framed, pre-1980, raised foundation, in an offered ZIP code |
| Supplemental income-eligible grant | up to $7,000 | Household income of $94,480 a year or less |
Grant amounts and the income threshold as published by the California Residential Mitigation Program, read 26 September 2026. These change between funding rounds — check the programme's own page before relying on a figure here.
What it costs
The programme states that a retrofit by a licensed contractor may cost between $3,000 and $7,000, depending on the size and location of the house, contractor fees, and how much material and work is involved. Done yourself as an owner-builder, it can come to under $3,000. Foundations needing more extensive work cost more.
Read that against the grant table above: for many eligible households the grant covers most or all of a standard job, and for an income-eligible household the two grants together can exceed the typical contractor cost.
Who does the work
If you hire someone, the programme requires you to choose from its Contractor Directory — California-licensed general contractors trained by FEMA in seismic retrofitting. Experienced do-it-yourselfers can act as owner-builder, but the value of your own labour is not a recoverable cost under the grant, and tools should be rented rather than bought.
Soft-storey buildings are a different problem
A "soft storey" is a building whose ground floor is mostly openings — tuck-under parking, or shopfronts — under several floors of apartments. In a strong earthquake that floor can collapse, taking the building with it. Several California cities, including San Francisco, Los Angeles, Oakland and Berkeley, have mandatory retrofit ordinances for these buildings, each with its own inventory, deadlines and engineering requirements. California also runs an Earthquake Soft-Story grant programme alongside Brace + Bolt.
Ordinance obligations sit with the building owner and the deadlines are legally enforceable, so if you own or are buying one, the city's own inventory is the authoritative source rather than any summary. We will publish a per-city table with verified deadlines when our address hazard tool ships; we are not going to publish an unverified one in the meantime.
Why it is worth doing beyond the damage
Two effects compound. A verified retrofit earns a CEA premium discount of up to 25%, and it removes the restriction that blocks pre-1980 raised-foundation frame houses from choosing the 5% and 10% deductibles. So the retrofit changes both what you pay and what you are permitted to buy.
Sources
Last checked:
- The Earthquake Brace + Bolt retrofit — grants, eligibility and typical cost — California Residential Mitigation Program
- Earthquake Brace + Bolt programme — California Residential Mitigation Program
- Retrofit discounts on CEA premiums — California Earthquake Authority
- Securing your water heater — Earthquake Country Alliance
- Earthquake safety at home — FEMA