FREQUENTLY ASKED QUESTIONS ABOUT SHORING

+ General Shoring

What does shoring mean for Construction Projects?

• Shoring is a method to support a building, vessel, structure, or trench with “shores”. Used when there is danger of collapse during repairs or alterations, shoring support is temporary.
• The structural support comes from shores that are constructed of timber or metal and used as props. Shoring installations may be vertical, angled, or horizontal, and used in one or a combination of orientations.

What is bracing?

• Bracing is any type of reinforcement made to the shoring system. Bracing can be achieved using rakers, struts, walers and tiebacks.

What are some types of shoring?

• Soldier pile and lagging
• Caisson wall
• Secant wall
• Pressure/chemical grouting
• Hydraulic shoring
• Soil nails and shotcrete
• Pneumatic shoring
• Sheet piles
• Box shoring

At what depth is shoring required, according to the Green Book? What is the Green Book?

• The depth of shoring required depends on the type of earth. Anything over 4’ must be shored, and in some cases shoring will be required at shallower depths.
• The Green Book is the Ontario Occupational Health and Safety Act and Regulations. Updated each year by the Ontario Ministry of Labour, the Green Book lays out the legal requirements for workplaces, including construction projects.
• Sections R-153 through R-167, 222 through 242, outline regulations that relate to shoring, bracing, and earths.

What is the angle of repose and how is the angle of repose of neighbouring buildings calculated?

• The angle of repose is the steepest angle a given soil or granular material can be piled at without collapsing. A 10:7 ratio is used for the calculation, measured from the neighbouring footing.

What is a Shoring Plan?

• A shoring plan is a set of drawings which show the detailed shoring design and specifications. It is prepared by a Professional Engineer.
• Planning for potential hazards (such as overburden loads, adjacent structures, overhead lines), as well as logistical factors (such as adjacent structures, staging of building materials, construction vehicle traffic, crane placement and load) are important parts of the shoring plan.

What should shoring plans include?

• Illustrated scope of work
• Sequencing of activities
• Specifications for building materials
• Overlaid utility drawings

Does shoring need to be engineered?

• All shoring needs to be engineered and reviewed by a licensed Engineer.

Typical things to look for on a shoring design:

• Which system is being used (soldier pile/lagging, secant wall, etc.)?
• Are there any underground or overhead utilities near or in conflict with the design?
• What soil conditions will likely be encountered when drilling?

What is passive resistance of the hole and caisson?

• A pile’s overturning force is related to its embedded depth. A pile with a deeper embedded pile “toe” will be more resistant to overturning than a shallower one.
• Local site conditions, such as ground water and tree plantings, will impact passive resistance and dictate how much load the shoring system can support.

+ Read More About Shoring & Excavation

At what depth of excavation do you typically need shoring for house construction in the city of Toronto?

• Generally, anything deeper than 8’ will require shoring in the city of Toronto.

What is benching or stepping of an excavation?

• Benching or stepping is a technique used to create progressively deeper un-shored plateaus within an excavation.