What Makes Marin Sites Challenging
- Steep hillside lots. Much of Marin’s housing sits on slopes in places like Mill Valley, Sausalito, Tiburon, Belvedere, Larkspur, and the hills above San Rafael. Hillside sites need careful cut planning, drainage control, and often retaining walls, soil nails, or deep foundations.
- Tight access. Narrow roads, hairpin driveways, and limited parking can rule out large equipment and long trucks. Equipment size, delivery timing, and haul-off have to fit the access you actually have.
- Soft ground near the bay. Low-lying areas along the bay shoreline and marshland edges, including parts of Corte Madera, Larkspur, Mill Valley, San Rafael, Sausalito, and Novato, can sit on soft bay mud or fill, which affects foundation design and settlement.
- Slope stability. Hillside soils and weathered rock can be prone to sliding, especially after heavy winter rain. Drainage, erosion control, and staged excavation are critical on these sites.
- Local review. Each Marin town, and the County for unincorporated areas, has its own building, grading, and design review process. Many also regulate tree removal and work near creeks.
Marin Ground Conditions
Marin’s hills are largely made up of fractured and weathered bedrock, with clay-rich soils and loose slope deposits on top in many places. The flatter areas near the bay often sit on soft, compressible bay mud. Some sites have both: a house on firm hillside ground with a driveway or addition that steps down onto softer soil. Expansive clays, perched groundwater, and old fill from earlier grading are common surprises.
We work from the project’s geotechnical report and coordinate with the geotechnical engineer and structural engineer, so the excavation, shoring, and foundation approach fit the ground on your site.
Services for Marin County Projects
Hillside Excavation and Grading
Excavation for foundations, basements, garages, additions, and driveways on sloping lots, plus grading with drainage and erosion control planned in.
Shoring and Soil Nails
Shoring for hillside cuts and lot-line excavations, including soldier pile and lagging, tiebacks, and soil nail walls, to keep cuts, roads, and neighboring homes stable during construction.
Helical Piles
Helical piles suit many Marin sites. Installation produces little vibration, the equipment can be compact for tight access, and capacity can be confirmed through installation torque. They’re used for new foundations, additions, decks, and underpinning, and can reach firmer ground beneath soft bay mud, subject to the engineer’s design.
Foundations and Retaining Walls
Structural concrete for footings, grade beams, retaining walls, and slabs, coordinated with excavation and drainage.
Underground Utilities
Utility installation for water, sewer, storm drain, and dry utilities, including laterals and site drainage, on hillside and flatland sites.
Demolition
Demolition of existing homes, garages, decks, and site features ahead of new construction, with protection for neighbors and access roads.
Permitting Across Marin
Permitting differs from town to town, so we work with owners, architects, engineers, and general contractors on the steps that affect our scope, including grading and drainage plans, construction schedules, and neighbor considerations on shared roads. Permit responsibility depends on how each project is contracted.
Planning for Weather on Hillside Sites
Winter rain changes the risk on Marin hillsides. Open cuts, stockpiles, and disturbed slopes need erosion and drainage control, and some excavation work is better scheduled for drier months when the project allows. We talk through the schedule early so the work is sequenced around the season and the site stays stable.
One Contractor for the Whole Site
On a Marin hillside, demolition, excavation, shoring, foundations, and drainage all depend on each other. LVI Engineering keeps those scopes with one team, which means fewer trucks and crews competing for a narrow road, fewer handoffs, and one schedule. We can also support preconstruction and design-build-assist work, helping owners and designers compare foundation and retaining options before drawings are final.
Safety comes first on every site, and on steep ground especially. LVI sets a goal of a zero incident rate and runs a Safety Rewards Program that recognizes safe work practices in the field.
Communities We Serve in Marin County
We take on projects in Marin’s incorporated towns and in its unincorporated communities. Areas we serve include:
- Southern Marin: Sausalito, Marin City, Mill Valley, Tamalpais Valley, Homestead Valley, Strawberry, Tiburon, and Belvedere
- Central Marin: Corte Madera, Larkspur, Greenbrae, Kentfield, Ross, San Anselmo, Fairfax, San Rafael, Terra Linda, and Santa Venetia
- Northern Marin: Novato, Marinwood, Lucas Valley, and Bel Marin Keys
- West Marin: Woodacre, Forest Knolls, Lagunitas, San Geronimo, Nicasio, Olema, Point Reyes Station, Inverness, Stinson Beach, and Bolinas
Don’t see your community? If it’s in Marin County, call us.
Marin County FAQs
Are helical piles a good fit for hillside homes in Marin?
They often are, especially where access is tight, vibration is a concern, or the soil is soft or variable. Your geotechnical and structural engineers decide whether helical piles suit your site and loads, and we can install to their design.
Can you get equipment up a narrow or steep driveway?
We plan equipment around the access. On tight sites that can mean compact machines, smaller trucks, and more trips. We’ll review access during the site walk.
Do you work in unincorporated Marin as well as the towns?
Yes. We take on projects in Marin’s incorporated towns and in unincorporated communities.
How does winter weather affect hillside excavation?
Rain increases the risk of erosion and slope movement on open cuts. We plan erosion control and drainage, and schedule the riskiest work for drier periods when the project allows.
Get a Quote for Your Marin County Project
Send us your plans, geotechnical report, and schedule, and we’ll help you plan the excavation, shoring, foundation, and utility work for your Marin site. You can also see the other areas we serve.
Call the office at 415-599-9575, call Joe directly at 415-305-5034, or email joe@lviengineering.com.
LVI Engineering · 1485 Bayshore Blvd, Suite 320A, San Francisco, CA 94124
