Screw Piles in Calgary, AB

Below the surface in Calgary

People often describe “Calgary soil” as if it were one thing, and pricing a job on that assumption is a mistake we run into constantly. Across the north and east the city rests on glaciolacustrine clay that swells and shrinks a great deal — it can heave one corner of a deck during a wet spring and let it settle back by late summer. Close to the Bow and the Elbow it is a different story: river-terrace gravels, sands and silts, where the depth to competent bearing can shift within the width of a back yard.

Communities down in the river valleys also deal with perched water, held above the regional water table. Digging and forming a concrete footing in that is a wet, frustrating job. A screw pile is barely bothered by it, and that is a big part of the reason engineers call for piles on those terraces.

In older inner-city districts, what lies under the lawn is more history than geology. A lot in Killarney, Renfrew or Mount Pleasant may have seen two or three houses over the decades, and the yard can conceal old demolition debris, coal ash, a backfilled cistern or the foundation of a house torn down generations ago. You cannot see any of it from above. That is why each helical pile is signed off on the torque we measure, not on a depth written in advance — piles a few metres apart on the same lot can legitimately stop at quite different depths.

The projects we see locally

Much of what we install in Calgary supports new construction on lots that already have a house: laneway homes and garden suites, additions off the back, detached garages sitting on grade beams carried by piles, and replacement decks. The soil is rarely what makes these jobs hard. Getting in is. Picture a 7.5-metre inner-city lot with the house along one side, a fence along the other and the rear lane as the only entry — no concrete truck or full-size excavator will fit, and the mature boulevard trees mean the approach cannot be widened either.

Our screw pile equipment travels in by the lane, leaves next to no spoil, needs no forms and no curing time, and the street is clear for the neighbours by evening. Out in the newer suburbs it is another kind of job altogether: easy access, consistent clay, and routine decks, hot tubs and garages on soil that shifts with the seasons.