Foundation & Basement Excavation

Foundation & Basement Excavation for Calgary Custom Homes and Infills

Every basement in Calgary started as a hole somebody dug, and the way it was dug decides how well the house sits, drains and ages. We handle the full foundation cycle: basement digs on open lots and acreages, tight-access excavation on inner-city infill lots, the excavation side of underpinning and basement lowering, and the controlled backfill and perimeter grade that close it all up.

A rectangular basement excavation with a flat clay floor and walls cut back at a slope.

What This Work Covers

Foundation and basement excavation covers four jobs that look similar from the street and are very different in the ground. A new-home basement on an open suburban lot or acreage is a volume-and-precision job: a large excavator, tri-axle trucks, a laser off the surveyor's benchmark and a plan for where every cubic metre of soil goes. An infill basement on a narrow inner-city lot moves less soil but is controlled by what is next door, so it runs on zero-tail-swing mini and midi machines, engineered shoring beside neighbouring foundations and laneway trucking. The same word, basement, describes both; the equipment, sequence and risks do not match.

The other two jobs bracket a foundation's life. Underpinning and basement lowering happen under a house that already exists and is often occupied, which means breaking out the old slab, carrying soil out through a single opening and digging below live footings only in the sequence a structural engineer has designed. Foundation backfilling and perimeter grading happen at the end of every new foundation: checking bracing, damp-proofing and weeping tile, placing suitable material against the wall in compacted lifts, and shaping the ground to fall away from the house at the slope the City of Calgary requires within 1.2 m of the foundation.

What ties the four together is the set of rules they share. The National Building Code 2023 Alberta Edition requires foundations to bear on undisturbed soil, sets minimum foundation depths by soil type and whether the space is heated, and controls what backfill may sit against the wall. The Alberta OHS Code requires protection wherever a worker is in an excavation deeper than 1.5 m and closer to the wall than its depth, requires engineer-designed protective structures deeper than 3 m, and requires engineered support for any existing foundation the dig may affect. Knowing which of those rules applies to which job is most of the difference between a clean foundation and an expensive repair.

Foundations & Basements Services

An excavator digs the last corner of a deep rectangular basement excavation with benched walls on an open acreage lot.

Deep Basement Excavation

Full and walkout basement digs for new custom homes on open lots and acreages.

How it works

A freshly dug basement excavation with sloped walls fills a narrow inner-city lot between an older bungalow and a new two-storey infill house.

Infill Lot Digging & Tight-Access Excavation

Mini and midi excavator digs on narrow infill lots beside neighbouring homes.

How it works

In an old basement with the floor slab removed, one short pocket of soil has been dug out beneath the existing concrete footing while the soil on either side stays in place.

Underpinning & Basement Lowering Prep

Excavation and spoil removal for engineered underpinning and basement lowering.

How it works

A compact track loader places backfill in a layer along a new concrete foundation wall with black damp-proofing and a drainage membrane.

Foundation Backfilling & Perimeter Grading

Compacted backfill against new foundations and a perimeter grade that sheds water.

How it works

Choosing Between Them

Open lot or acreage, new house: Choose deep basement excavation. If there is room for a full-size excavator to work and trucks to turn, and nothing existing sits close to the dig, the job is about hitting the design elevations, shaping safe side slopes and managing the soil.
Narrow lot between existing homes: Choose infill lot and tight-access excavation. If neighbouring foundations are close to the new basement, access is by laneway or there is no room to stockpile, you need smaller zero-tail-swing machines and a dig sequenced around shoring.
Keeping the house, want a deeper basement: Choose underpinning and basement lowering prep, and bring in a structural engineer first. Digging below existing footings is only done to an engineered design, in the sections and order it specifies.
Foundation is poured, hole is still open: Choose foundation backfilling and perimeter grading once walls are braced or framed as required and drainage is checked. If the house is older and the basement leaks, you likely need weeping tile excavation instead.

Why It Matters Around Calgary

Calgary's housing stock splits these jobs by geography. The inner-city communities, such as Renfrew in the northeast and Hillhurst along the Bow in the northwest, are where infill basements, tight-access digs and basement lowering tend to concentrate, often on narrow lots with neighbours close by and services that may be decades old. Some of those river-adjacent communities also carry groundwater questions worth checking against the City's Regulatory Flood Map before going deeper. Around the edges of the city and in growing neighbours such as Airdrie, which reported 1,623 housing permits for new homes in 2025, the work is more typically open-lot basement digs followed by backfill and grading to an approved lot drainage design.

Beyond the city limits, acreage foundations follow a different rhythm. In Foothills County, De Winton sits among traditional acreages, while Heritage Pointe is a golf-course community on communal piped water and wastewater, so the excavation around a new house there works around service lines rather than a septic field. Foothills County allows no construction, including foundation or excavation work, until a permit has been issued. Everywhere in the region the ground freezes deep: Calgary frost typically reaches around 2 m in a normal winter and reached 2.4 m in 2019, which shapes how open excavations and backfill are handled through the cold months.

Foundations & Basements: Common Questions

On a knock-down and rebuild, what order do the foundation jobs happen in?

Typically the old house is demolished under its own permit first, with services disconnected and the water service cut off at the main by an indemnified contractor. The infill excavation follows, sequenced around any engineered shoring for neighbouring foundations. Footings and walls are formed and poured, and new water, sanitary and storm connections in the City right-of-way are installed by a utility indemnified contractor. Once walls are braced or framed as required and weeping tile and damp-proofing are checked, the foundation is backfilled in compacted lifts and the perimeter is graded to slope away from the house.

When does a basement or foundation dig need a professional engineer?

Several points in the Alberta OHS Code bring one in. Any existing foundation the excavation may affect, whether your own house or a neighbour's, must be supported by an engineer-designed temporary protective structure before digging starts. Protective structures in excavations deeper than 3 m must be engineer-designed, and an engineer can certify ground as stable in place of cut-backs or shoring. Underpinning and basement lowering are designed by a structural engineer as a matter of course, and where a new-home lot has a geotechnical report, it sets the bearing conditions the dig must meet.

Can the same contractor dig the basement and come back to backfill it?

Yes, and there are practical advantages. The crew that dug the hole knows the soil, where the backfill stockpile was placed and which material was set aside as unsuitable, so the soil plan made on digging day carries straight through to backfill. It also means one party is responsible for the over-dig from the first bucket to the finished perimeter grade. The gap between the two visits depends on footings, walls, damp-proofing, weeping tile and framing, so the backfill date is set by the builder's schedule, not the excavator's.

Other Excavation Services

Site Prep & Earthmoving

Trenching & Hydrovac

Demolition & Removal

Drainage & Erosion Control

Commercial & Specialized

Talk to Us About Foundations & Basements

Tell us about the site, what is there now and what is going in. We will recommend the scope that fits, including when a smaller job will do.

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