Two people look at the same sloping hallway. One calls it a foundation problem. The other says the floor framing has sagged and the foundation is fine. A third bid proposes work on both. All three may be describing part of the truth, and the homeowner is left wondering whether “structural repair” and “foundation repair” are two different jobs or two names for one.
They overlap, and that overlap is what trips people up. This post maps the line: what sits on each side, where the two halves meet, which symptoms can start on either side, and who designs and builds each piece in California. For our services, see the structural repair and foundation repair pages. For how weight actually travels through a house, read the companion post on load path basics.
Foundation repair is one branch of structural repair. The useful line isn’t between two trades. It’s between the part of the house that bears on soil and the part that bears on the foundation, and the hardest calls sit right where those two meet.
One system, two halves
California’s residential code doesn’t treat the foundation as a separate thing bolted onto a house. It describes one system. Construction under the code “shall result in a system that provides a complete load path” carrying loads “from their point of origin through the load-resisting elements to the foundation” (CRC R301.1). The foundation’s own job is defined as accommodating all of those loads “and of transmitting the resulting loads to the supporting soil” (CRC R401.2).
So “structural repair” is the broad family: any repair to the parts of a building that carry gravity or lateral loads. “Foundation repair” is the lowest branch of that family, covering the elements that hand the load to the ground and the way they bear on it. The code expects footings to sit on “undisturbed natural soils or engineered fill” (CRC R403.1), which is why soil questions belong to the foundation side.
What sits on each side
The foundation side usually means:
- Footings, including the continuous footings under exterior walls
- Concrete or masonry stem walls in a raised-floor house
- Slabs on grade
- Piers, pads, and grade beams
- Underpinning that extends support deeper
- The soil interface itself: bearing, settlement, drainage at the footing
The side above the foundation usually means:
- Posts and girders in the crawl space
- Floor joists and subfloor
- Bearing walls and the headers over their openings
- Rafters, ceiling joists, and trusses
- Shear walls and the connections that tie each level to the next
California law lists these together. The state’s description of the B-2 Residential Remodeling license says that class “shall not contract to make structural changes to load bearing portions of an existing structure, including, but not limited to, footings, foundations, load bearing walls, partitions, and roof structures” (CSLB, citing BPC §7057.5). Footings and roof structures sit in the same sentence because they are links in the same chain.
The interface zone
Many disagreements about “foundation or structural?” start where wood meets concrete or where a post meets the ground. These are the spots to look at closely in any report or bid.
Sill plate and anchorage. The wood plate on top of a stem wall belongs to the framing, but it bears on the foundation and is attached to it. Decay or crushing there can look like settlement from inside the house. Seismic anchorage of that plate is its own topic, covered in our bolt-and-brace overview.
Posts on piers or pads. A crawl-space post is framing; the pad under it is foundation. The code requires columns to be “restrained to prevent lateral displacement at the bottom end” (CRC R407.3) and wood columns to be protected against decay (CRC R407.1). A post that has rotted, slipped, or lost contact with its pad can produce the same sloping floor as a pad that has sunk.
Cripple walls. Short framed walls between a stem wall and the first floor are framing that does foundation-level work. Our cripple wall bracing basics post explains them.
Girder ends at the stem wall. Where a girder sits in a pocket or on a pier, the code sets a minimum seat: at least 1½ inches of bearing on wood or metal, or 3 inches on masonry or concrete, unless approved hangers are used (CRC R502.6). A short or deteriorated seat is a framing problem sitting on a foundation element.
Slabs on grade. In a slab house, the floor and the foundation are often the same piece of concrete. Distinguishing slab movement from structural need is the subject of concrete leveling vs structural repair.
Retaining walls that carry the house. On a hillside lot, a wall that holds back soil may also support a footing. It belongs to both lanes. See retaining wall repair.
Symptoms that can start on either side
The same symptom can come from below or above. This table lists possibilities, not diagnoses. Only an evaluation on site sorts them out.
| Symptom | Possible foundation-side causes | Possible framing-side causes |
|---|---|---|
| Sloping or uneven floor | Settled footing, pier, or pad; soil movement | Sagging girder; undersized, cut, or notched joists; decayed post or sill |
| Sticking doors, racked openings | Differential settlement | Header deflection; bearing wall removed or altered above |
| Diagonal cracks at door and window corners | Foundation movement | Header or beam deflection; framing movement |
| Floor pulling away from baseboards | Slab or footing movement | Joist sag or a failed bearing point |
| Bouncy or springy floor | Possible if supports below have moved | Joist span or spacing; joists cut for pipes or ducts |
Our sloping floors checklist, sticking doors and windows, and structural vs cosmetic wall cracks posts go deeper on each symptom.
Why the line matters for the repair
A fix on one side can leave the cause on the other. Shimming a post on a pad that is still sinking makes the floor flat for a while. Underpinning a corner under a girder that is sagging mid-span leaves the sag. The question to keep asking is whether a proposal addresses the cause it says it is addressing.
Repair and remodel follow different code paths. The Existing Building Code defines a repair as “the reconstruction, replacement or renewal of any part of an existing building for the purpose of its maintenance or to correct damage,” and an alteration as “any construction or renovation to an existing structure other than a repair or addition” (CEBC §202). Fixing a decayed girder is a repair. Removing a bearing wall to open a kitchen is an alteration. When both happen at once, expect the documents to sort out which is which.
Work across the line can belong to the repair. The code says work on undamaged components “that is necessary for the required repair of damaged components shall be considered part of the repair” (CEBC §401.2). If reaching a failed footing means shoring and opening framing, that framing work is part of the repair scope. Our post on how inspections inform repair scope covers how damage level changes what the code requires.
Who designs and who builds each side
Design. California’s engineering board says civil engineers “prepare design and repair recommendations for drainage systems, septic systems, foundations, and retaining walls,” and analyze buildings for gravity, earthquake, and wind. Geotechnical engineers evaluate soil and rock and how they interact with foundations. Structural Engineer is a title held by civil engineers who passed an additional exam. Our post on when to involve a structural engineer explains those titles.
For conventional wood-frame houses, state law lets some plans be prepared without a license. But when any portion “deviates from substantial compliance with conventional framing requirements,” the building official “shall require the construction documents to be approved and stamped by a California licensed architect or engineer for that irregular or non-conforming portion” (CRC R301.1.3.1). The board adds that cities “usually require that a licensed engineer prepare … foundation design in areas where the soil may be a problem.” Framing repairs and foundation repairs can land in different places on that spectrum within the same house.
Construction. The Contractors State License Board issues licenses by classification. A B General Building contractor works on structures requiring “at least two unrelated building trades or crafts.” Specialty classes include C-8 Concrete and C-5 Framing and Rough Carpentry. As quoted above, a B-2 Residential Remodeling contractor may not contract structural changes to load-bearing portions, foundations included. Check the license and classification on the CSLB site against the actual scope, for both sides of the line.
Roles during the job. The board’s consumer guide is blunt about the split: “the engineer draws the plans and the contractor does the construction,” and the engineer has no duty to supervise unless that is added to the contract. Engineer observation also “does not replace any required inspections by the local jurisdiction.”
The City. In San Diego, a Building Permit is required before a structure is “altered, repaired, improved” and so on, unless a narrow exemption applies (SDMC §129.0202). Information Bulletin 120 (October 2025) states that “all construction that requires a permit must be inspected before it is covered or concealed.” That applies on both sides of the line. Our San Diego permit basics post covers the permit side.
Questions to ask when a bid covers only one side
- What cause does this bid say it is fixing, and what evidence supports it?
- Does anything above the foundation (posts, girders, joists, sills) need attention for this repair to work?
- If framing must be shored, jacked, or opened to reach the foundation, whose scope is that?
- Who designs each part, and whose stamp appears on which sheets?
- Which license classification performs each part of the work?
- Who pulls the permit, and which inspections apply before anything is covered?
For a broader list, see questions to ask a foundation company.
Where we fit
We look at both halves of the house during an evaluation: the foundation and the framing that sits on it. Where soils, design, or stamped documents are required, we coordinate with licensed engineers as needed. Nothing in this post is legal or engineering advice, or a determination about any specific house.
Next step
If you have a floor, wall, or opening that’s moving and you’re unsure which side of the line it starts on, request a Free Quote for an evaluation anywhere in La Jolla, or call (650) 739-6537.
Sources (accessed October 16, 2026)
- 2025 California Residential Code, Sections R301.1, R301.1.3.1, R401.2, R403.1, R407.1, R407.3, and R502.6
- 2025 California Existing Building Code, Section 202 (definitions of Repair and Alteration) and Section 401.2
- Contractors State License Board, Description of Classifications (B, B-2 per BPC §7057.5, C-5, C-8)
- Board for Professional Engineers, Land Surveyors, and Geologists, A Guide for Consumers and Building Design Authority
- San Diego Municipal Code §129.0202
- City of San Diego Information Bulletin 120, Building Inspection (October 2025)