Foundation
Contractor

A foundation contractor handles the excavation, forming, and concrete work that creates the structural base of a building. This starts with evaluating the site — soil conditions, drainage, and topography — then excavating to the required depth and dimensions, setting forms, and placing concrete for footings, slabs, stem walls, or grade beams depending on the foundation type.

A good foundation contractor also integrates waterproofing and drainage systems during the build, not as an afterthought. And in cases where an existing foundation has developed problems, they assess the cause and perform repair work to stabilize the structure.

Sonoma County has significant deposits of expansive clay soil — particularly in the valley floors and lower hillside areas. Expansive clay absorbs moisture and swells during the wet season, then dries and shrinks in summer. This repeated cycle creates movement that can crack concrete, shift stem walls, and cause foundations to heave or settle unevenly over time.

The solution isn't to avoid these soils — they're everywhere — but to design and build foundations that account for them. That means appropriate excavation depth, proper drainage to minimize moisture variation, and concrete mixes and reinforcement suited to expansive soil conditions. A soils report from a geotechnical engineer is often required and always helpful for foundation work in Sonoma County.

We work with all residential and commercial foundation types common on the Central Coast, including slab-on-grade foundations, raised foundations with crawl spaces, stem wall foundations, continuous footings, spread footings, and grade beams. The right type for a given project depends on the soil conditions, the structure's load requirements, drainage characteristics of the site, and local building code requirements.

We discuss foundation type selection during our initial site evaluation — it's one of the first decisions that shapes everything downstream.

Yes, in virtually all cases. Foundation work for new construction requires a building permit, and significant foundation repair or replacement typically requires one as well. In Sonoma County, any grading exceeding 50 cubic yards or 3 feet in depth also requires a separate grading permit. Monterey County's threshold is 100 cubic yards.

We coordinate permit applications as part of our service. If a soils report is required — which it often is for hillside lots or sites with known soil issues — we'll identify that early so it doesn't become a scheduling problem later.

Drainage is one of the most critical factors in long-term foundation performance, and it's consistently underinvested in on projects where cost pressure is high. Water is the primary enemy of foundations — it contributes to expansive soil movement, creates hydrostatic pressure against walls, promotes concrete degradation, and in high water table areas can cause uplift forces that compromise the structure from below.

We design drainage into every foundation project from the start: perimeter drains, subdrain systems where needed, waterproofing membranes, and final site grading that moves water away from the structure. These aren't optional add-ons — they're part of building a foundation that actually lasts.

Common indicators include diagonal cracks at the corners of doors or windows, doors or windows that stick or no longer close properly, visible cracks in the foundation itself (especially horizontal or stair-step cracks in block foundations), floors that feel unlevel or springy, gaps between walls and ceilings, and in more serious cases, visible bowing or bulging of foundation walls.

Not all foundation cracks are structural — hairline shrinkage cracks in concrete are normal — but cracks that are widening, horizontal, or accompanied by movement are worth having evaluated. We can assess whether a foundation issue requires repair and what the appropriate approach would be.

We do both. Foundation repair work includes crack injection and sealing, underpinning to stabilize a settling foundation, adding drainage systems to relieve hydrostatic pressure on existing walls, reinforcing deteriorated sections, and in some cases partial or full foundation replacement.

The right repair approach depends on what's causing the problem. Before we propose any repair, we evaluate the site to understand the root cause — whether it's drainage, soil movement, inadequate original construction, or something else. Treating the symptom without addressing the cause usually means the problem returns.

Timeline varies significantly by scope. A straightforward residential slab foundation — excavation, forming, and concrete pour — might be completed in one to two weeks excluding concrete cure time. A full crawl space or basement foundation with forming, waterproofing, and drainage integration could take three to four weeks or longer depending on site access and complexity.

Concrete cure time is a fixed constraint that affects scheduling regardless of how quickly the preceding work moves. Standard concrete achieves working strength in about seven days and full design strength at 28 days, though framing can typically begin before that point in most residential projects. We discuss realistic timelines during the planning phase so you can schedule downstream work accordingly.

It depends on the project and location. In Sonoma County, soils reports are often required by the building department for new foundations on hillside lots or in areas with known expansive or unstable soil conditions. In Monterey County, similar requirements apply on sloped parcels and in areas subject to liquefaction or erosion.

Even when not required, a soils report is valuable — it tells us what we're actually working with before we dig, which allows us to design the foundation appropriately rather than discovering problems mid-project. We can help you determine whether a report is needed for your specific site and project type.

Yes. DW Excavation, LLC holds California Contractor's License #1060838 as a General Engineering Contractor. This license covers foundation excavation, grading, earthmoving, and related site preparation and concrete work throughout California.

We carry appropriate general liability insurance and workers' compensation coverage for all work we perform. You can verify our license status at any time through the California Contractors State License Board at cslb.ca.gov.