Soil Conditions in Los Angeles
Los Angeles County's geology is as varied as its neighborhoods. Here's what we typically find.
Alluvial Basin Deposits
Much of the LA Basin is underlain by deep Quaternary alluvial deposits consisting of interbedded sands, silts, and clays. These soils can vary in density and compressibility over short distances, making site-specific borings essential for accurate foundation design.
Hillside Formations (Puente & Fernando)
The Hollywood Hills, Baldwin Hills, and Mt. Washington areas are underlain by the Puente and Fernando formations — Miocene-age sedimentary bedrock including siltstones, sandstones, and shales. These units are prone to landslides on steep slopes, particularly where bedding planes daylight on cut faces.
Fault Zone Considerations
The City of Los Angeles straddles multiple fault zones including the Hollywood, Santa Monica, and Newport-Inglewood faults. Alquist-Priolo fault setback zones and seismic hazard zones for liquefaction and landslide are mapped throughout the city and frequently trigger additional geologic investigation requirements.
Variable Fill and Former Agricultural Land
Large areas of the city, especially in the San Fernando Valley and South LA, were formerly agricultural or industrial. Undocumented fill of variable thickness and composition is common, often requiring removal and recompaction or deep foundation alternatives.
What We Do in Los Angeles
Soils Reports
Geotechnical investigation and foundation recommendations for building permits.
Learn more →Grading Plans
Precise and rough grading design with drainage and earthwork calculations.
Learn more →Compaction Testing
Field density testing and fill certification for construction.
Learn more →Stormwater / LID / WQMP
LID/WQMP compliance and BMP design.
Learn more →Hydrology Reports
Drainage analysis and flood risk assessment.
Learn more →Subsurface Exploration
Drilling, CPT, and test pit programs.
Learn more →Erosion Control Plans
SWPPP and erosion control for grading permits.
Learn more →Street Improvements
Frontage, curb, gutter, and sidewalk design.
Learn more →Utility Plans
Water, sewer, and storm drain design and coordination.
Learn more →Project Coordination
One point of contact managing structural, MEP, surveying, and specialty consultants.
Learn more →We also coordinate with your structural engineer, architect, MEP consultants, and other project team members to ensure our deliverables integrate with the overall design — one point of contact for your geotechnical and civil engineering scope.
What People Build in Los Angeles
ADU / Accessory Dwelling Unit
Los Angeles leads the state in ADU construction. Most ADU permits require a soils report, especially on hillside lots or in mapped hazard zones.
Hillside Single-Family Home
New homes and major remodels in the Hollywood Hills, Bel Air, and similar hillside areas require comprehensive geology and soils investigations, engineered retaining walls, and caisson or pier foundations.
Multi-Family / Mixed-Use Development
Infill apartment and mixed-use projects throughout the city require geotechnical reports addressing foundation design, shoring, and dewatering for subterranean parking levels.
Commercial Tenant Improvement
While many TI projects do not require new geotechnical work, additions or mezzanines that increase structural loads may trigger LADBS soils report requirements.
Retaining Walls and Slope Repair
Hillside properties frequently require engineered retaining walls or slope stabilization. LADBS requires geotechnical design parameters and geology reports for walls over four feet in retained height.
Working With Los Angeles Department of Building and Safety (LADBS)
LADBS requires geotechnical investigations for most new construction, grading permits, and projects within mapped hazard areas. The soils report must be approved by LADBS Grading Division before plan check can proceed. Hillside properties are subject to additional review under the Hillside Construction Regulations.
What Makes This Jurisdiction Distinct
Soils and geology reports required per LAMC Section 91.7006 for new construction and significant grading
Hillside Construction Regulations (ZI-2462) impose grading quantity limits, haul route permits, and slope height restrictions
Properties with Zoning Information (ZI) files may trigger mandatory geotechnical and geologic investigation
Alquist-Priolo fault zone and seismic hazard zone (liquefaction, landslide) studies required when within mapped areas
Grading plans must include haul route maps when export or import exceeds 1,000 cubic yards
LADBS requires the geotechnical report to be uploaded to the online plan check system (PCIS) with the grading or building permit application. The report must bear the wet signature and stamp of the licensed Geotechnical Engineer and, where applicable, the Certified Engineering Geologist.
Common Questions — Los Angeles
Building in Los Angeles?
Tell us about your project and we'll send you a fixed-fee proposal — typically within one business day.