When something seems wrong with a retaining wall, the decision about who should look at it, and how closely, tends to get made in a hurry. This guide is meant to help you make it calmly, ideally before anything goes wrong. It covers four questions that decide whether a wall needs a structural evaluation, what that evaluation checks, what it can’t see, and what you’ll get back.
It’s written for retaining walls: garden walls, walls under driveways and patios, and walls that hold up a pad or a slope. If you’re worried about cracks in the walls of your house, start with our wall cracks page and our room-by-room guide to structural vs cosmetic wall cracks.
The short version: a failing wall more than two feet tall should be seen by a structural engineer. A wall that carries a house footing, a driveway, or a fence, or sits on expansive soil or a mapped hazard, can’t be rebuilt from the City’s standard drawings; a licensed engineer or architect has to design it. If you plan to rebuild a wall like that, or add weight on top of any wall, bring in a design professional first. A short wall with nothing on top that isn’t changing may only need watching.
Question 1: Is the wall failing, and how tall is it?
HUD’s Residential Rehabilitation Inspection Guide is direct on this point: “Failing retaining walls more than two feet in height should be inspected by a structural engineer.”
“Failing” covers more than collapse. HUD’s guide tells inspectors to “check for bowing (vertical bulges), sweeping (horizontal bulges), and cracking in retaining walls that can be caused by water pressure,” and adds that “bulging can also be a result of inadequate strength to resist the load of the earth behind the wall.” It names overturning (“leaning from the top”), sliding, settling, and heaving as other ways walls fail.
The same guide explains why timing matters. “Bowing and sweeping failures may be correctable if found early enough and if the cause is poor drainage.” “Both overturning and sliding may be stabilized and sometimes corrected if the amount of movement is not extreme.” But “significant failure of any kind usually requires rebuilding or replacing all or part of a wall.” One of its photo captions makes the point about quick fixes: “Simply patching the crack will not solve the problem.”
If you’re not sure whether a wall is changing, a season of dated photos and marks will tell you more than a single look. Our retaining wall monitoring checklist shows how to set that up, and it lists the changes that mean you should call right away rather than keep watching.
Question 2: What is the wall holding up?
A wall that holds back only soil in a level yard has a simpler job than one with a driveway, a house footing, or a fence line on top. The City and the code both treat that difference as decisive.
The California Residential Code, as adopted in San Diego, requires an engineered design for retaining walls not supported at the top that retain more than 48 inches of unbalanced fill, and for “retaining walls exceeding 24 inches (610 mm) in height that resist lateral loads in addition to soil” (Section R404.4). City Information Bulletin 220 counts “driveways, walkways, structure footings, fences, etc.” as surcharge loads that trigger a permit. Our companion post on retaining wall vs foundation interaction explains how a house footing near the top of a wall loads it.
This question matters for walls you’re planning, too. If you want to add a parking pad, a spa, or a fence near the top of an existing wall, the wall is about to take on a new job. That’s the time to ask, before the weight goes on.
Question 3: What is the site like?
The City publishes standard designs for masonry cantilevered retaining walls in Information Bulletin 221. They cover walls “not exceeding 6 feet in height with level or sloping backfills,” with sloping backfill no steeper than 1.5 horizontal to 1 vertical. But the bulletin limits where they can be used. The designs “may not be used to retain expansive soils, surcharge loads, or to impound flammable liquids,” and they may not be used on sites with any of these geologic hazards:
- Fault zones and ground ruptures
- Landslides and potential slope stability problems
- Liquefaction and potential ground failure
- Coastal bluff stability
- Variable stability or unfavorable geologic structure with sloping topography
The bulletin points to the City’s Seismic Safety Study maps “to determine site-specific geologic hazards.” Our post on Mount Soledad hillside foundation considerations explains how to use those maps and how not to over-read them.
When a wall falls outside IB-221’s limits, the bulletin says it “shall be designed by a civil engineer, structural engineer, or architect licensed in the State of California,” and adds that “a geotechnical investigation may be required depending on the project location.” On a hillside lot, that can mean both a structural design and soil input. Our post on when to involve a structural engineer explains the difference between civil, structural, and geotechnical engineers, and how to check a license.
Question 4: What are you about to do?
A wall evaluation can start with a plan, not a crack. The plan changes what’s needed.
- Leave it and watch it. Reasonable for a short wall with nothing on top that isn’t changing. Keep a record.
- Repair the drainage. HUD says weeps and drains “should be examined closely following a reasonably heavy rain,” and if they aren’t discharging, “the drains should be cleaned out and observed again in the next rain.” If that doesn’t work, HUD describes the fix as “excavating behind the wall, replacing the drainage material and damaged drainage piping, and backfilling.” Digging behind a wall that’s already moving is a job to plan with an evaluator.
- Rebuild or replace. Whether a contractor can build from the City’s standard drawings depends on Questions 2 and 3. If the wall is over 6 feet, carries surcharge, retains expansive soil, holds back a slope steeper than 1.5 to 1, or sits on a mapped hazard, the standard design is out.
- Add something on top. See Question 2.
- Buy or sell the property. If a home inspection report flags a wall, an evaluation gives both sides something more specific than “recommend further evaluation.”
Two measurement details catch people out. For structural design, IB-221 measures wall height “from the top of the footing to the top of the wall (including wall caps).” For zoning, it measures “from the finished grade on the lower side of the retaining wall to the top of the retaining wall.” Those can be different numbers for the same wall. The bulletin also notes that “retaining walls higher than 5 feet may require a grading permit.” For the 3-foot permit exemption and when it doesn’t apply, see our post on leaning retaining wall causes.
What a structural evaluation of a wall looks at
An engineered wall design has to show the wall is stable “against overturning, sliding, excessive foundation pressure and water uplift” (CRC R404.4). An evaluation of an existing wall asks the same questions about what’s already there: is it tipping, is it sliding at the base, is the soil under the footing holding, and is water building up behind it?
The New York City Department of Buildings’ training material on inspecting old retaining walls gives a sense of what a careful visual inspection records. Its assessment form covers the wall itself (top of wall outward or inward, bulging or warping, settlement, cracks, previous repairs), the ground around it (tension cracks in the soil at the top, sinkholes, the soil and paving at the base and top), water (whether weeps are functioning, erosion, water or silt coming through the wall, downspouts from adjacent buildings), and attachments (fences, sheds, trees, and storage near the top). It also notes that checking the alignment along the top of the wall can show whether segments are rotating, and can clear up confusion between a wall built leaning back on purpose and one that’s moved.
If a geotechnical engineer is involved, the City’s Guidelines for Geotechnical Reports expect retaining wall recommendations for “allowable bearing pressures, coefficient of friction against sliding, passive resistance, and lateral pressures,” with lateral pressures that “account for potential surcharge loads, hydrostatic pressure, expansive soil, adverse geology, slopes, etc.”
What an evaluation can’t see
A visual inspection has limits, and a good report says so. The NYC material lists two: “When the RW has a veneer, in most cases the condition of the backup cannot be observed,” and “the presence or condition of piles cannot be observed.” Its form asks the inspector to record whether the condition of the wall’s backup structure was reliably assessed, partially assessed, or not assessed. Vegetation cuts both ways: the deck notes it hides a wall’s condition and can deteriorate the wall.
Buried drains, footing size, and reinforcement are hidden from view too. Sometimes the only way to answer those questions is to open something up, test the soil, or find the original plans. That’s a real limit of visual inspection, and a report should say where it applies.
What you’ll get back
That depends on the answer.
- Observation findings. If the wall is sound or the issue is maintenance, you may get a written description of what was seen, what to watch, and what to fix.
- A design path. If the wall needs to be repaired or rebuilt beyond the City’s standard design, IB-221 says the submittal “shall include plans and structural calculations,” and engineer-designed walls “are subject to special inspection requirements specified in Chapter 17 of the California Building Code.”
- A soils question. If the site has a slope, fill, or expansive soil, the next step may be a geotechnical investigation before anyone designs a fix.
One more City rule to keep in mind if your wall is near a lot line: “All elements of retaining walls shall be maintained within the applicant’s property; encroachments into neighboring properties shall not be allowed.”
What to bring to the evaluation
- Your monitoring photos and log, if you have them
- Any permit records or approved plans for the wall (our seller documentation checklist explains how to search City records)
- Any geotechnical report for the property
- A note of what sits on top of the wall and what’s changed recently: new fences, plantings, irrigation, a spa, or construction nearby
- Where the downspouts and wall drains empty
Cost factors, not prices
We don’t publish prices. What shapes the scope of a wall evaluation and any follow-up work: wall height and type, what the wall supports, whether the site has mapped hazards or expansive soil, whether a geotechnical investigation is needed, whether the design can follow the City’s standard drawings or needs engineered plans and calculations, drainage condition, access on a slope, and permit requirements.
Where we fit
We evaluate retaining walls on site for homeowners across La Jolla and explain what we see before recommending anything. When a wall needs engineered design or a soils investigation, we coordinate with licensed engineers as needed; our structural engineer page describes how that works, and our retaining wall repair page covers repair and permits. This post is general education, not an engineering opinion about any specific wall.
Next step
If a retaining wall on your property is bulging, leaning, or about to take on new weight, request a Free Quote for an on-site evaluation anywhere in La Jolla, or call (650) 739-6537. For hillside lots, our hillside foundation repair page covers the slope side.
Sources (accessed October 20, 2026)
- U.S. Department of Housing and Urban Development, Residential Rehabilitation Inspection Guide (2000), Section 1.2
- San Diego Residential Code 2025 (California Residential Code with City of San Diego amendments), Section R404.4
- City of San Diego Information Bulletin 221, Standard Cantilevered Retaining Walls (December 2023)
- City of San Diego Information Bulletin 220, retaining wall permits (October 2024)
- City of San Diego, Guidelines for Geotechnical Reports (2008), Section 6.6.2.4
- New York City Department of Buildings, “Inspection of Old Retaining Walls,” D. Eschenasy, P.E., Build Safe | Live Safe Conference (2014)