What Is Shoring and Why Do Toronto Sites Need It?
Shoring is a temporary wall that holds soil in place beside an excavation. Without it, the sides of a deep hole slump or collapse, and anything sitting near the edge, a neighbour’s house, a sidewalk, a gas main, moves with them. On open land you can slope the sides of a hole instead, but a safe slope in Toronto clay needs roughly as much horizontal room as the hole is deep. On a 25 ft lot with houses on both sides, that room does not exist.
That is why shoring is part of most Toronto excavation: underpinning beside a party wall, knock-down rebuilds on infill lots, commercial buildings digging to the property line, and sewer trenches on busy streets. We design, install and monitor it, with our own P.Eng signing off each stage.
Types of Shoring We Use
Soldier piles and timber lagging
Steel H-piles are drilled or driven along the edge of the excavation before digging starts. As each lift of soil is removed, timber lagging boards are slid in between the piles to hold the soil. This is the workhorse system for Toronto infill and commercial sites.
Rakers and walers
Steel walers run horizontally across the piles. Rakers are diagonal braces from the walers down to footings at the base of the excavation. They are simple and need no neighbour agreements, but they take up space inside the hole.
Tieback anchors
Tiebacks are drilled behind the wall and grouted into firm soil, holding the wall from behind and leaving the excavation clear. When they cross a lot line, the neighbour must agree in writing.
Trench boxes and hydraulic shores
For sewer, watermain and pipe gallery trenches, steel trench boxes give workers a protected space and move along the trench as work progresses.
Engineered benching
Where there is some room, the soil is cut back in steps, typically 1.2 m high, so no single face is too tall. It is the cheapest method when the lot allows it.
Caisson and secant pile walls
Overlapping or closely spaced concrete piles make a stiff wall that resists groundwater and heavy loads. They cost more but are used beside sensitive buildings or below the water table.
Choosing the Right System
| System | Best for | Space inside hole | Relative cost |
|---|---|---|---|
| Engineered benching | Open lots, shallow to moderate depth | Uses lot space, not hole | Lowest |
| Trench box | Utility trenches | Clear | Low |
| Soldier pile + lagging with rakers | Infill and commercial, no anchors allowed | Rakers occupy base | Moderate |
| Soldier pile + lagging with tiebacks | Commercial, clear hole needed | Clear | Moderate to high |
| Caisson or secant wall | High water, sensitive neighbours | Clear | Highest |
The Rules: O. Reg. 213/91 and OBC Part 4
O. Reg. 213/91, the construction regulation under Ontario’s Occupational Health and Safety Act, is clear: an excavation deeper than 1.2 m that workers enter must be sloped, benched or shored, and engineered systems must be built to stamped drawings and inspected. For Large Buildings under OBC Part 4, excavation support must be designed by an engineer. Our principal, Marko Pavlovic, is a licensed Ontario P.Eng and BCIN Part 4 qualified, so design and field review stay inside the company.
Monitoring: How Neighbours Stay Safe
Shoring moves a little as soil load comes onto it. The question is how much. Before excavation we survey the condition of neighbouring buildings and install monitoring points, often survey prisms on walls and points on sidewalks. The engineer sets alert and action levels. Readings are taken through the dig and shared with the GC. On a Yonge-Eglinton mid-rise with an apartment building 1.4 m from the lot line, readings never passed the alert threshold and there were zero neighbour claims.
When to Call Us
If your excavation is deeper than about 1.2 m and sits near a building, road, utility or lot line, you probably need shoring. Send us the drawings and geotechnical report, or book a site visit, and we will propose a system with design, install and monitoring priced in writing within 24 hours.
