Calgary foundation services
Foundation Underpinning in Calgary
Someone told me my house needs underpinning. Is that really necessary?
Underpinning means extending a foundation down to soil that can carry it, or transferring its load onto piles that reach that soil. It is genuinely required when a footing has lost bearing support and settlement is ongoing, or when a basement is being deepened. It is not required for most cracks, most leaks, or settlement that has stabilised. Because it is expensive and irreversible, a second opinion and an independent engineer's assessment are worth the delay.
We are a referral service, not a contractor. Your request goes to an independent Calgary foundation company.
Underpinning is the heaviest intervention in residential foundation work, and it is occasionally recommended where something considerably less would do. It is also, in the cases that genuinely need it, the only thing that works.
This page is written to help you tell those apart before committing to a five-figure decision.
Situations where underpinning is genuinely considered
- Worth monitoring: Differential settlement that measurement shows is still active
- Worth monitoring: A footing bearing on fill or soil with inadequate capacity
- Worth monitoring: A basement being deepened for headroom, requiring the foundation to go lower
- Worth monitoring: An addition whose foundation depth must match an existing shallower one
- Worth monitoring: Excavation next door that has undermined support
- Worth monitoring: Severe, progressive movement that lesser repairs have failed to arrest
Why a foundation loses bearing
The original footing may have been placed on soil that was adequate at the time but has since changed, most commonly through moisture-driven volume change in clay.
It may have been placed on fill that has continued to consolidate, which is more common on lots where the original grade was substantially altered.
Water is the frequent accelerant, whether from a leaking service, poor drainage or a long-term change in the water table.
Adjacent excavation, for a neighbouring basement or a utility trench, can remove lateral support and cause movement that was not there before.
In basement-deepening projects there is no defect at all: the foundation is sound but does not extend as deep as the new floor level requires, so it has to be extended downward.
Underpinning methods
Method selection is an engineering decision driven by soil conditions, loads and access, not a matter of contractor preference.
Helical piles
Screwed into the ground beside the footing to reach bearing soil, with brackets transferring load onto them. Installed with relatively compact equipment, which matters on tight urban lots.
Best suited to: Most residential settlement work where soil conditions allow screwing to depth.
Push or resistance piers
Driven hydraulically using the building's own weight as the reaction. The installation itself demonstrates the capacity achieved.
Best suited to: Heavier loads and cases where verified capacity is important.
Mass concrete underpinning
The traditional method: excavating beneath the footing in short, carefully sequenced sections and filling each with concrete before moving to the next. Labour-intensive and slow, but requires no specialised plant.
Best suited to: Basement deepening and situations where piling equipment cannot get access.
Bench footing
An alternative to full underpinning when deepening a basement. Rather than extending the existing footing down, a stepped ledge is formed inside the perimeter. It sacrifices some floor area but is often cheaper and less risky.
Best suited to: Basement lowering where losing perimeter floor space is acceptable.
How an underpinning project runs
Independent structural assessment
A professional engineer establishes whether underpinning is required at all, and if so over what length. Where the recommendation came from a contractor who would also perform the work, an independent opinion is worth obtaining.
Geotechnical investigation
Test holes establish what the soil profile is and at what depth adequate bearing exists. This determines pile length and therefore a large part of the cost.
Design and permits
The system is designed and stamped. Structural work of this kind requires permits and inspection.
Sequenced installation
Work proceeds in sections so the structure is never unsupported over a significant length. This sequencing is the reason the work is slow and the reason it is safe.
Load transfer and verification
Load is transferred onto the new support and movement is monitored. Some projects lift toward the original elevation; many stabilise in place.
Cost and Calgary conditions
What drives the price
Piling work is priced per pile, so the total scales with the length of footing needing support. Alberta sources publish per-pile figures in the low thousands, which for a typical affected wall length puts whole projects well into five figures.
Why this behaves differently in Calgary
Calgary's clay till means the depth to reliably competent bearing soil varies substantially across the city and even across a single lot. That variability is why a geotechnical investigation, rather than an assumption, drives the design.
The city's mix of housing eras also matters. Inner-city homes on shallow or rubble foundations present quite different underpinning problems from suburban homes on modern engineered footings, and the methods that suit them differ accordingly.
When to get someone in
Worth acting on now
- Get this looked at: Settlement that measurement confirms is still progressing
- Get this looked at: Structural movement that earlier repairs have not stopped
- Get this looked at: Visible distress following excavation on an adjacent property
Reasonable to monitor
- Historic settlement that monitoring shows has been stable for years
- Cracks with no measurable differential movement behind them
- A contractor recommending underpinning without a supporting engineer's report
Questions people actually ask
When is underpinning actually required?
When a footing no longer has adequate bearing support and movement is ongoing, or when a basement is being deepened below the existing foundation. Cracks, leaks and settlement that has stabilised do not on their own call for underpinning. The deciding evidence is measured, active differential movement, which is why an engineer's assessment comes before any quote.
How disruptive is underpinning?
Substantially. Access is needed around or under the affected footing, which usually means excavation inside the basement, outside the house, or both, along with removal of landscaping or finishes in the way. Projects run from days to weeks depending on method and length. Homes are often occupied throughout, but the affected area is not usable.
Should I get a second opinion before agreeing to underpinning?
Yes. It is the most expensive and least reversible residential foundation repair, and the assessment often comes from a company that would also do the work. An independent professional engineer with no interest in the outcome is the appropriate check, and the cost of that report is small relative to the project.
What is bench footing and how does it compare?
Bench footing forms a stepped concrete ledge inside the basement perimeter instead of extending the existing footing downward. It is generally faster and cheaper than full underpinning and carries less structural risk, at the cost of losing a strip of floor area around the perimeter. It applies to basement lowering projects, not to settlement repair.
Get this looked at by a Calgary contractor
Tell us what you are seeing and roughly where you are. We pass it to an independent Calgary foundation contractor who contacts you directly.
We are a referral service, not a contractor. Your request goes to an independent Calgary foundation company.