A house on a slope has to meet the ground at more than one height. Some La Jolla homes do it with a foundation that steps down the hill under a single floor. Others split the floor itself, so the living room sits a half-flight below the kitchen and a garage or bedroom wing tucks into the hillside. Either way, the places where the elevation changes are the places worth a careful look.
This post is about the house, not the lot. If you want to know how slope geology, mapped hazards or soils shape a hillside property, start with our Mount Soledad hillside foundation considerations post and our geotechnical (soils) report explainer. Here we stay with the concrete and framing at the steps: what the code expects, what earthquake research has found about stepped and split-level buildings, and what a homeowner can actually see.
Two ways a house changes elevation
It helps to separate two conditions that get lumped together.
A stepped foundation under one floor. The floor framing stays flat, but the footing and the wall below it drop in stages as the grade falls away. Between the top of the concrete and the floor you get a short framed wall on the uphill side and a taller one downhill. Those short framed walls are cripple walls, and on a slope they come in a staircase of heights.
A split-level floor. Here the floors themselves sit at different heights. One wing might be slab-on-grade while the other is framed over a crawl space, or a garage with a room above meets the main house about half a story off. The foundation has to step, and so does the framing.
Some hillside homes have both. FEMA’s seismic retrofit prestandard for one- and two-family wood houses (FEMA P-1100) describes hillside dwellings that “often include lower partial floor levels as the dwelling steps down the slope,” with foundations that “can include stepped, sloped, continuous concrete footings, with or without concrete stem walls, isolated spread footings, cast-in-place concrete piers or caissons, or combinations of these.” Our post on La Jolla older homes and foundation types walks through those systems; this one looks at what happens where they change height.
What the code says about stepping a footing
The residential code adopted in San Diego (the 2025 California Residential Code with City amendments) starts simple. Under Section R403.1.5, “The top surface of footings shall be level,” and “Footings shall be stepped where it is necessary to change the elevation of the top surface of the footings or where the slope of the bottom surface of the footings will exceed 1 unit vertical in 10 units horizontal.” In plain terms, a footing isn’t supposed to just tilt down a hill. It drops in level steps.
Framing over a stepped foundation gets its own rule in Seismic Design Categories D0 through D2. Section R602.11.2 applies “where the height of a required braced wall line that extends from foundation to floor above varies more than 4 feet.” Where it applies, the code covers the step itself:
- “Where the lowest floor framing rests directly on a sill bolted to a foundation not less than 8 feet (2440 mm) in length along a line of bracing, the line shall be considered as braced.”
- The top plate of the cripple wall is spliced “by extending the upper top plate not less than 4 feet” along the foundation.
- “Anchor bolts shall be located not more than 1 foot and 3 feet (305 and 914 mm) from the step in the foundation.”
- Where cripple walls sit between the foundation and the floor, the cripple wall bracing sections apply.
The cripple walls carry their own rules. Section R602.9 says “Cripple walls shall be supported on continuous foundations,” and taller ones, “Where exceeding 4 feet (1219 mm) in height, such walls shall be framed of studs having the size required for an additional story.” The bracing section goes further: if any segment is taller than 48 inches, “the entire cripple wall shall be counted as an additional story.” On a walk-out lot, “Cripple walls or wood-framed basement walls in a walk-out condition shall be designated as the first story.”
That’s a lot of code, and you don’t need to memorize it. The takeaway is that the step is a detail the code pays attention to, with specific bolt locations, plate splices and bracing. Older homes were built to whatever rules applied at the time, so an existing house won’t necessarily match today’s text. That’s not automatically a problem. It’s a reason to look.
Why the steps matter in an earthquake
FEMA P-1100 and its commentary are direct about stepped and split-level houses.
On split levels: “The term split-level is used for dwellings that have vertical offsets in their framed floors. In past earthquakes separations have occurred between portions of the dwelling having different floor levels, in some cases leading to collapse of a portion of the dwelling.” The fix it describes is about connection: “Mitigation for split-level dwellings involves adequate connections between portions of the dwelling to resist separation.” It also says houses with those floor offsets “were beyond the scope of this prestandard,” and that “Not specifically addressed by this prestandard is the additional split-level vulnerability of separation between the one-story and two-story wings of the dwelling.” So the prescriptive retrofit path doesn’t cover them. They go to engineered design.
On stepped crawl-space walls, the commentary describes what investigators saw after Northridge: “the stepped crawlspace wall starts out as a single wall segment, but as the top of the wall is laterally loaded during the earthquake, it eventually breaks into individual segments, with the number of segments corresponding with the number of wall steps.” Computer models showed a sequence some call “unzipping,” where “the stiffest uppermost crawlspace wall segment reaches peak capacity first” and the next step follows. FEMA is careful here too. It notes that laboratory testing “did not identify reduced capacity or stiffness of moderately stepped cripple walls relative to level cripple walls,” and that steeply stepped walls may behave differently. Even with that caveat, it helps to know which segment the models say reaches its limit first: the short one at the top.
The uphill side gets attention for a related reason. For houses that project out over a slope, FEMA found “the primary seismic response was found to be torsional rotation about the uphill foundation,” and “The connection of the base-level diaphragm to the uphill foundation is the stiffest load path for seismic loading, and insufficient strength can result in brittle failure of this connection in earthquakes.” FEMA’s analysis flagged sites of “1 vertical to 5 horizontal or steeper” as the point where hillside houses respond differently from level-lot crawl-space houses. Our cripple wall bracing basics post covers bracing on level lots. On a slope, the uphill connection and the stepped walls are a separate question for an engineer.
The uphill wall that holds back soil
In a split-level home on a slope, the lower floor may sit against the hill. The concrete wall on that side does two jobs: it supports the house and it holds back earth. The code treats that wall as a foundation wall, not a garden retaining wall. The retaining wall section (R404.4) says it “shall not apply to foundation walls supporting buildings.” The same wall then picks up moisture rules. “Drains shall be provided around concrete or masonry foundations that retain earth and enclose habitable or usable spaces located below grade,” and dampproofing applies to “foundation walls that retain earth and enclose interior spaces and floors below grade.”
That’s why a damp lower-level wall in a split-level house is a different conversation from a damp patio wall. Our posts on how retaining walls and foundations interact and retaining wall types and how they fail cover freestanding walls; for walls that are part of the house, the retaining wall repair and hillside foundation repair pages explain how we approach them.
Water at the steps
Every step in a foundation is a place where water can collect. Rain running downhill meets the uphill wall first. Under the code’s drainage section, “Lots shall be graded to drain surface water away from foundation walls,” and where slopes or walls make the standard fall impossible, “drains or swales shall be constructed to ensure drainage away from the structure.” On a hillside lot, the drainage plan has to account for each step as well as the perimeter.
Soil near a slope also moves on its own schedule. A homeowner guide from the California Geotechnical Engineering Association (CalGeo) notes that “Slope creep can occur along the face of a slope and within a short distance back from the top of the slope,” and that “Slope creep can be reduced by maintaining uniform soil moisture levels.” That’s one reason steady drainage and irrigation matter around stepped footings near the downhill edge. Our hillside drainage before structural repair post and the foundation drainage page go deeper on the water side.
If the house sits on a graded pad, part cut into the hill and part filled, the City’s geotechnical report guidelines ask consultants to “Recommend measures to mitigate potential differential soil movement across cut/fill transitions.” Our cut-and-fill lots post explains why a step in the house can line up with a step in the ground underneath.
What you can see at the steps
You don’t need a crawl suit for a first look. Walk the outside and, where it’s safe, look in from the crawl-space access.
- The step in the concrete. Is it a clean, level step, or does the footing seem to slope? Cracks that start at the inside corner of a step are worth photographing.
- Where the floors meet. In a split-level house, look at the short stair or landing between levels. Gaps opening at the top or bottom riser, cracks in drywall above the opening, or doors that start to bind at the transition are clues to note and date.
- The cripple walls. Look at the tallest and the shortest segments. Is there sheathing? Can you see bolts near the step? Is there dark staining or soft wood at the bottom plate on the uphill side?
- The uphill wall. Damp patches, white mineral deposits or a musty lower room point to water against a wall that holds back soil. Our post on efflorescence on foundation walls covers that clue.
- The downhill edge. Look for gaps opening between the house and patios, steps or walks on the low side, and for cracks that track toward the slope.
Take dated photos from the same spots so you can compare later. Our crack monitoring post shows a simple method.
Questions worth asking
- Where does this house change elevation, in the foundation, in the floors, or both?
- Are there stepped cripple walls, and how tall are the tallest and shortest segments?
- How is the uphill wall connected to the floor above it?
- Where the floors split, what ties the two parts of the house together?
- Is the wall against the hill drained and dampproofed, and is there any record of it?
- Does this need an engineer’s review, and does the site need geotechnical input?
Cost factors, not prices
We don’t publish prices. What shapes the cost of evaluating a stepped or split-level foundation includes the number of steps and transitions, how much of the crawl space can be reached, whether the uphill wall retains soil against living space, whether finishes hide the framing at the split, whether drainage needs to be studied along with the structure, and whether the work needs engineered drawings or geotechnical review.
Where we fit
We’re a foundation and structural repair company serving La Jolla citywide, and hillside homes with steps and split levels are part of that work. We can document what’s happening at each transition and help you understand what you’re looking at before decisions get made. We aren’t engineers. We work with verified contractors and coordinate with licensed engineers as needed. This post is general education, not an assessment of any property. Our foundation inspection page explains what an on-site evaluation covers.
Related evaluations & services
- Hillside foundation repair: foundations on sloping lots
- Retaining wall repair: walls that hold back soil
- Foundation drainage: moving water away from the steps
- Foundation inspection: getting an evaluation
- Earlier post: La Jolla older homes and foundation types
- Earlier post: Mount Soledad hillside foundation considerations
Next step
If your hillside home has stepped footings or a split-level floor and something at a transition has changed, request a Free Quote for an on-site visit anywhere in La Jolla, or call (650) 739-6537.
Sources (accessed October 31, 2026)
- San Diego Residential Code (2025 California Residential Code as amended), Chapter 4, §§R401.3, R403.1.5, R404.4, R405.1, R406.1, via UpCodes
- San Diego Residential Code (2025 California Residential Code as amended), Chapter 6, §§R602.9, R602.10.10.3, R602.11.2, R602.12.4, via UpCodes
- FEMA P-1100, Vulnerability-Based Seismic Assessment and Retrofit of One- and Two-Family Dwellings, Volume 1 – Prestandard (October 2019), Chapter 6 and Commentary
- California Geotechnical Engineering Association (CalGeo), Coexisting with Expansive Soil: An Informational Guide for Homeowners (2013)
- City of San Diego, Guidelines for Geotechnical Reports (2008), §6.6.1.3