Cracked foundations
Concrete cracks for many reasons: shrinkage as it cures, temperature, age, tree roots, water, soil movement or earthquake shaking. A crack's width on its own does not tell you which of these caused it or whether it is still changing.
What helps is context: where the crack is, its direction and pattern, whether one side is offset from the other, whether it lines up with cracks inside the house, and whether it changes over months. Date-marked photos taken from the same spot are more useful than a single measurement.
Filling or sealing a crack is cosmetic or a moisture measure; it is not a structural diagnosis and does not show that movement has stopped.
Settlement and uneven floors
Sloping floors, doors that stick and diagonal cracks above openings can come from foundation settlement — but also from framing that sagged over decades, deteriorated posts or sills in a crawl space, past remodels that removed support, or seasonal moisture swelling doors and frames.
Telling these apart usually takes an on-site look at the foundation, the crawl space and the framing together. Where soil movement is suspected, a geotechnical engineer is the professional who can investigate it; the California Geological Survey's hazard zones show where such investigation may be required, not what is under a particular house.
Seismic bolting and bracing do not correct settlement, and leveling a floor does not by itself address why it moved.
Slab versus raised foundations
A raised foundation lifts a wood floor above the ground on perimeter walls and interior supports, leaving a crawl space. Much of what affects it — sills, posts, piers, moisture, anchorage — can be seen from below. A slab-on-grade is a concrete floor on the ground; its underside cannot be seen, so evaluation relies more on surface signs, floor elevations and, when needed, engineering investigation.
The two types call for different questions. Seismic brace-and-bolt work, as described by the California Residential Mitigation Program, applies to raised wood-frame houses. Plumbing leaks, cracking and settlement can affect either type, but are investigated differently.
Neither type is "better" in general; what matters is the condition and the question being asked.
Crawl-space supports and post-and-pier conditions
Under many raised floors, interior beams rest on wood posts standing on concrete piers or pads. Over time, posts can rot or split where they meet damp concrete or soil, piers can tilt or sink, and earlier owners may have added shims, jacks or blocks of uncertain quality.
These conditions are often repairable as part of a defined scope, but whether a support is adequate — and what should replace it — depends on what it carries and how it connects. FEMA P-1100 treats crawlspace dwellings as a distinct configuration with specific earthquake vulnerabilities at cripple walls and sill anchorage; gravity supports and seismic vulnerabilities are related but separate questions.
Adding a post or a jack under a sagging beam is not a substitute for understanding why the beam sagged.
Underpinning and stabilization
Underpinning extends a foundation's support to deeper or more competent soil. Systems include helical piers (screwed in), push or resistance piers (driven or pressed using the weight of the house), drilled piers and conventional concrete underpinning. Pressure foundation jacking and the injection of concrete or mortar for stabilization are named in the California State License Board's D-30 classification (Pile Driving and Pressure Foundation Jacking).
Choosing whether to underpin, which system, and where, is an engineering decision based on a soils investigation and the structure. Hillside stabilization — retaining structures, deep foundations, drainage — is a geotechnical and structural design problem, often with its own permits. Slab lifting by injecting polyurethane foam or grout can raise some concrete flatwork, but lifting concrete is not automatically a remedy for a load-bearing foundation.
These methods are described for reference. KB Remodeling does not claim to perform them or to hold the D-30 classification; when a project needs them, we say so and coordinate with the engineer and the appropriate specialty contractor.
Drainage and moisture around foundations
Water is involved in many foundation complaints: soil that softens or swells, wood that rots in a damp crawl space, efflorescence on concrete, or erosion near footings. Common contributors are downspouts discharging next to the wall, ground sloping toward the house, irrigation close to the foundation, and leaking supply or drain lines.
Observing where water goes during and after rain is one of the most useful things an owner can do before a site visit. Correcting a visible drainage cause is often part of a sensible repair scope; designing site drainage for a new home or a hillside is covered separately in the grading and drainage guide.
Moisture control supports a foundation; it does not repair structural damage that has already occurred.