Field notes / Homeowner guide
Foundation repair vs earthquake retrofitting: different problems, different fixes
A seismic retrofit strengthens how a house holds onto its foundation in shaking. Foundation repair fixes damage or movement in the foundation itself. They are often confused, and one does not do the other's job.
Written · KB Remodeling
The short answer
Choose based on the problem. Settlement, cracking, sloping floors and water damage are repair questions. Missing anchorage and unbraced cripple walls on a raised house are retrofit questions. If the concrete is damaged, it usually has to be addressed before or as part of a retrofit.
Who this applies to
Owners of raised wood-frame houses, and anyone with a proposal that combines or confuses the two. It is not a design guide and does not determine program eligibility.
01 · When it applies
What a retrofit does
CRMP describes the common single-family retrofit as bolting the house frame to the foundation and, where short cripple walls stand in the crawl space, bracing them with plywood. The aim is to reduce the chance of the house sliding or toppling off its foundation in shaking.
It does not level floors, close cracks, stop settlement or improve drainage.
Ask yourself
- Does your house have a crawl space, and are there short walls in it?
Source for this section
02 · Comparing the options
Side by side
The table separates the questions each type of work answers.
| Foundation repair | Earthquake retrofit | |
|---|---|---|
| Problem addressed | Damage, movement or deterioration in the foundation | Weak connection between house and foundation, unbraced cripple walls |
| Typical signs | Cracks with offset, sloping floors, water, crumbling concrete | No visible anchors at the sill; short unbraced walls in a crawl space |
| Who designs | Engineer for structural repair | Standard plan where the house qualifies; otherwise an engineer |
| Typical standard | Engineer's design for the condition | CEBC Chapter A3 or FEMA P-1100 plan sets, per CRMP |
| Fixes settlement? | Can, depending on method | No |
| Needs sound concrete? | Addresses the concrete | Yes; anchors need sound concrete to hold |
| Grant programs | Not part of CRMP retrofit grants | CRMP programs may apply, subject to current eligibility |
03 · The decision
When you need both, and in what order
If the evaluation finds deteriorated concrete under a house that also lacks anchorage, the concrete is dealt with first or as part of an engineered retrofit; bolting into failing concrete is not a fix. Houses with living space over a garage have a separate vulnerability CRMP addresses with FEMA P-1100 plan sets, in addition to any crawl-space retrofit.
Costs differ too: a retrofit's cost reflects anchorage and bracing, not foundation repair, so one should never be used to estimate the other.
Ask yourself
- Did the evaluation look at concrete condition before recommending a retrofit?
04 · Next step
Permits apply to both
Retrofits and structural repairs are permitted by the building authority for the address — LADBS in the City of Los Angeles, the relevant city or the County elsewhere. The plan path (standard plan or engineered design) is confirmed with that authority.
Source for this section
A scenario to consider
A 1920s raised house has unanchored sills and one crumbling corner of the stem wall. The engineer designs replacement of that corner and a brace-and-bolt retrofit together, so anchors go into new, sound concrete.
Planning scenario
Bring this to your conversation
- Identify whether the house is raised or on a slab
- Look for short walls in the crawl space
- Note visible anchors or plates at the sill
- Record concrete condition and any cracks
- Note any room over the garage
- Check program eligibility on CRMP's own site
One more question
Will a retrofit stop my floors from sloping?
No. Sloping floors are a repair or framing question. A retrofit strengthens the house-to-foundation connection for earthquakes.
Official references
Prepare plans and ADUs · Web resource · English source
CRMP — The Earthquake Brace + Bolt retrofitUse this for: Understand bolt-only and brace-and-bolt retrofits and program rules; eligibility is set by the program.
Prepare plans and ADUs · Web resource · English source
CRMP — The Earthquake Soft-Story retrofitUse this for: Understand living-space-over-garage retrofits and program rules; eligibility is set by the program.
Prepare plans and ADUs · Web resource · English source
FEMA — P-1100 seismic retrofit of one- and two-family dwellingsUse this for: Background on the FEMA seismic retrofit standard for one- and two-family dwellings; not a design for your house.
Prepare plans and ADUs · Web resource · English source
LADBS — Plan review and permittingUse this for: For City of Los Angeles parcels, find LADBS plan review, online permits and appointments.
For requirements specific to your property, consult the local reviewing authority.
About this guide
Published by KB Remodeling from the official sources cited. It is not attributed to an individual author and does not claim review by an architect, engineer or attorney. We receive remodel, ADU, new-home and rebuild inquiries; scope, licensing and location are reviewed before any next step.