What Is Construction Shoring?
Shoring is a temporary or permanent support system that holds back soil or supports a structure while work happens next to it or beneath it. On an excavation, shoring keeps the walls of the cut from collapsing. It also protects neighboring foundations, streets, and buried utilities from settlement. On an existing building, structural shoring carries loads while floors, walls, or foundations are removed, repaired, or replaced.
In California, a trench or excavation 5 feet or deeper that workers will enter generally needs a protective system under Cal/OSHA’s excavation rules (Title 8, Construction Safety Orders). Many urban excavations also need engineered shoring drawings as part of the building or site permit. Shoring isn’t optional extra cost. It’s what makes the rest of the project possible.
Shoring Systems We Install
Every site is different. The right system depends on soil and groundwater conditions, excavation depth, how close adjacent structures are, access, and schedule. Common systems on Bay Area projects include:
Soldier Pile and Lagging
Steel H-piles go into drilled holes at regular spacing, and lagging (usually timber or precast concrete) is placed between them as the excavation goes down. Soldier pile and lagging is a workhorse for basements, podium garages, and lot-line excavations. It can be cantilevered, braced internally, or tied back.
Tiebacks and Ground Anchors
Tiebacks are drilled, grouted anchors that reach behind the shoring wall into stable ground. They hold the wall in place without internal bracing, which keeps the excavation open for equipment and foundation work. Using them may require an encroachment or tieback agreement where anchors extend under a neighboring property or the public right-of-way.
Soil Nail Walls
Soil nailing reinforces the excavation face with closely spaced steel bars grouted into the soil, finished with a shotcrete facing. Soil nail walls work well in suitable soils on cuts and slopes, and they can be cost-effective where there’s room for the nails. See our Soil Nails page for more.
Raker and Internal Bracing
Rakers (diagonal braces) and walers transfer wall loads back to the excavation floor or to temporary footings. Teams use them when tiebacks aren’t allowed or practical, such as next to deep basements or utilities.
Underpinning
Underpinning extends an existing foundation deeper, so a neighboring building stays supported when the new excavation goes below its footings. Methods include sequenced hand-dug or drilled pits and, in some conditions, helical piles.
Trench Shoring
Hydraulic shores, trench boxes, and slide-rail systems protect crews during underground utility installation and other linear excavation.
Structural Shoring
Temporary vertical and lateral support for existing structures during renovation, seismic retrofit, partial demolition, or foundation replacement.
Bay Area Ground Conditions Shape the Design
The Bay Area packs a wide range of soils into a small footprint, and each affects shoring differently:
- Artificial fill and bay mud along the waterfront, South of Market, Mission Bay, and the Bayshore corridor can be soft and compressible, often with shallow groundwater.
- Dune sand in western San Francisco neighborhoods can cave easily during drilling and excavation.
- Hillside sites in Marin, the Oakland and Berkeley hills, and parts of San Francisco bring sloping ground, variable bedrock, and tight access.
- Seismic considerations affect permanent retaining structures and sometimes temporary systems.
We work from your project’s geotechnical report and coordinate with the geotechnical engineer, structural engineer of record, and shoring designer. The goal is a system that’s buildable, inspectable, and sequenced with the rest of the work.
Our Shoring Process
- Preconstruction review. We review the geotechnical report, survey, adjacent structures, utilities, and the excavation plan. Brought in early, we can help compare shoring options on cost and schedule (see Design-Build & Preconstruction).
- Design coordination and permits. We work with the shoring engineer and project team on drawings, submittals, and permit requirements, including any neighbor agreements for tiebacks or underpinning.
- Pre-construction surveys and monitoring. We document neighboring conditions and set up monitoring points as the design requires.
- Installation. We drill, set piles, place lagging, install and test tiebacks, and excavate in sequence with the shoring.
- Monitoring and handoff. We track movement during excavation, then turn over a stable excavation ready for foundations, and remove or abandon the system as specified.
Why Bundle Shoring With Excavation, Demolition and Utilities
Shoring rarely stands alone. On most urban sites it sits between demolition and foundation work, and it has to work around existing utilities. LVI Engineering is a general engineering contractor that also performs demolition, excavation, grading, utility installation, helical piles, and concrete work. One contractor across those scopes means fewer handoffs, cleaner sequencing, and a single team responsible for the hole in the ground.
Safety comes first on every excavation. LVI sets a zero-incident goal and runs an employee Safety Rewards Program that recognizes safe work practices in the field.
Shoring FAQs
Do I need shoring for my excavation?
If workers will enter a trench or excavation 5 feet or deeper, Cal/OSHA generally requires a protective system, unless the excavation is entirely in stable rock or is properly sloped or benched. Excavations next to property lines or existing foundations often need engineered shoring regardless of depth. Your geotechnical and structural engineers make the final call.
What’s the difference between shoring and underpinning?
Shoring holds back soil along the excavation. Underpinning extends a neighboring foundation deeper so it isn’t undermined. Many lot-line projects need both.
Can you work with an existing shoring design?
Yes. We can build to designs prepared by the project’s shoring engineer and offer constructability feedback during preconstruction.
What areas do you serve?
San Francisco, Marin County, the East Bay, Sonoma, Napa, Sacramento, Monterey, and the wider Northern California region. See all of our service areas.
Request a Shoring Quote
Planning an excavation in San Francisco or the Bay Area? Send us your geotechnical report, site plan, and schedule, and we’ll help you find a shoring approach that fits the site.
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
