Construction term · Glossary
Shoring
Verified vs OSHA sources · 2026-10-05
An excavation protective system that braces the walls in place — with hydraulic, pneumatic, mechanical, or timber supports — to prevent a cave-in. Unlike a trench box (which protects the worker after a collapse), shoring actively holds the soil back so it doesn't move. It's one of OSHA's accepted Subpart P systems.
Also known as: shoring system
On this page
Shoring at a glance
- Actively supports the walls to PREVENT a cave-in (vs. a shield, which protects after one).
- Types: hydraulic, pneumatic, mechanical (screw jack), and timber.
- Designs come from manufacturer/tabulated data or a registered professional engineer.
- Aluminum hydraulic shoring is common for fast, adjustable installation.
In plain English
Propping up the trench walls with braces or jacks so they physically can't collapse. It holds the dirt back — different from a trench box, which just shields you if the dirt does come down.
What the rule says
“Shoring (Shoring system) means a structure such as a metal hydraulic, mechanical or timber shoring system that supports the sides of an excavation and which is designed to prevent cave-ins.”
In context
A concept governed primarily by OSHA's construction standards, 29 CFR Part 1926 — the rules that apply on jobsites rather than the general-industry 1910 set.
Where this is written in OSHA's rules
- 29 CFR 1926.650(b)Read on eCFR / OSHA.gov
Example
A crew installs aluminum hydraulic shores in a utility trench: two vertical rails per side, spread by hydraulic cylinders that press the shoring firmly against the walls. The shoring holds the soil in place, so the trench sides can stay vertical without sloping the excavation wide.
Why it matters
Shoring lets crews work in narrow, deep trenches where sloping isn't practical — but only if it's rated for the depth and soil and installed per its tabulated data. Improvised or under-rated shoring is a serious Subpart P violation and a cave-in risk, so the design source (manufacturer data or a PE) matters.
Shoring vs. shielding (trench box)
Shoring PREVENTS a cave-in by bracing the walls so the soil can't move. A shield (trench box) does NOT prevent a cave-in — it's built to withstand one and protect the workers inside it. Both are accepted systems, but they work in opposite ways.
Common shoring systems
| Type | How it works |
|---|---|
| Hydraulic shoring | Hydraulic cylinders press rails/shores against the walls |
| Pneumatic shoring | Air-pressure cylinders (similar to hydraulic) |
| Timber shoring | Wood uprights, wales, and cross-braces per tabulated data |
| Mechanical (screw jack) | Threaded jacks manually tightened against the walls |
Shoring: frequently asked questions
- What is the difference between shoring and a trench box?
- Shoring braces the excavation walls to prevent a cave-in; a trench box (shield) doesn't prevent a cave-in but protects workers inside it if the walls fail. Shoring holds the soil; a shield shields the worker.
- What are the types of shoring?
- Hydraulic, pneumatic, mechanical (screw-jack), and timber shoring. Aluminum hydraulic shoring is widely used because it's lightweight and quickly adjustable.
- How is shoring designed?
- From the manufacturer's tabulated data, OSHA's Appendices C/D, or a design approved by a registered professional engineer — matched to the excavation's depth and soil type.
Related terms
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Governing OSHA standards
More Construction terms
The part of Title 29 of the Code of Federal Regulations that contains OSHA's General Industry standards — the default rulebook for most American workplaces (manufacturing, warehousing, healthcare, etc.) that aren't covered by the construction, maritime, or agriculture standards. It includes core rules like Hazard Communication (1910.1200) and the permissible exposure limits (1910.1000). Several 1910 standards are cross-referenced into construction via Part 1926.
29 CFR 1926The part of Title 29 of the Code of Federal Regulations that contains OSHA's Construction standards — the “Safety and Health Regulations for Construction.” It governs construction, alteration, and repair work, with construction-specific rules for fall protection (Subpart M), scaffolds (Subpart L), excavations (Subpart P), electrical (Subpart K), and more. Where a task isn't addressed in 1926, some general-industry (1910) standards apply by reference.
Anchor PointThe secure attachment point a personal fall arrest system (PFAS) ties off to — the “A” in the ABC of fall arrest. Under 29 CFR 1926.502(d)(15), a non-engineered anchorage must support at least 5,000 pounds per attached worker; alternatively, it can be an engineered anchorage designed and supervised by a qualified person with a safety factor of at least two.
Atmospheric TestingMeasuring the air in a confined space (or other hazardous atmosphere) with a calibrated direct-reading instrument before and during entry. OSHA requires testing in a set order — oxygen first, then flammable gases and vapors, then potential toxic contaminants — and defines the acceptable ranges: oxygen 19.5%–23.5%, flammables below 10% of the LEL, toxics below their exposure limits.
BenchingAn excavation cave-in protective system that cuts the sides into a series of horizontal steps (benches), usually with vertical or near-vertical faces between levels. It's one of OSHA's accepted protective systems under Subpart P — but it is NOT permitted in Type C (the least stable) soil.
Competent Person (Excavation)The competent person OSHA's excavation standard (Subpart P) requires on every trenching job — someone trained in soil classification and protective systems, who can identify cave-in and other hazards AND has authority to remove workers and correct problems. They must inspect the excavation daily before work starts, throughout the shift, and after any rain or event that could increase the hazard.
Confined SpaceA space that is large enough for a worker to bodily enter, has limited or restricted means of entry or exit, and is not designed for continuous occupancy. If it also contains — or could contain — a serious hazard (a hazardous atmosphere, engulfment material, an entrapping configuration, or any other recognized serious hazard), it becomes a permit-required confined space (PRCS).
Controlling EmployerUnder OSHA's Multi-Employer Citation Policy (CPL 02-00-124), the controlling employer is an employer with general supervisory authority over a worksite — including the power to correct safety and health violations itself or to require others to correct them. This is typically the general contractor or construction manager. A controlling employer can be cited for a hazard at the site even if none of its own employees are exposed, because it has a duty to exercise reasonable care to prevent and detect violations by the other employers on site.
Sources & verification
- 29 CFR 1926.650(b) (eCFR / OSHA.gov)
- OSHA — Trenching and Excavation
- 29 CFR 1926.652 — Protective systems (eCFR)
Reviewed by HazComFast against eCFR, OSHA.gov, NIOSH, and the Federal Register. Last reviewed 2026-10-05. This glossary is general information, not legal advice; OSHA State-Plan states (e.g. California, Michigan) may adopt stricter requirements.
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