Extend Shallow Footings with Foundation Underpinning
Older homes, additions, and basement deepening projects often expose a footing that was never sized for the load it carries. Gatineau Concrete extends those footings downward or outward in a controlled sequence of numbered bays, keeping the structure supported throughout the work. Every underpinning is engineered and the site assessment is free.
A cracked foundation wall can sometimes be repaired by reinforcing the wall itself. But when the root cause is a footing that is too shallow, too narrow, or sitting on poor bearing soil, wall repair alone will not stop the movement. The footing must be extended or rebuilt to a deeper, wider, or better-bearing section.
Underpinning also solves two other common scenarios: lowering a basement floor to gain headroom (the existing footing must be extended downward first), and adding a second storey or room where the new load exceeds the original footing capacity. In each case, the concrete slab or structure sits on a footing that was never designed for what is now on top.
The solution is always the same principle. The existing footing is supported in numbered bays while a new, deeper or wider section is poured beneath or beside it. The work is engineered so the building never loses support. We coordinate underpinning with basement renovation, crack sealing, and waterproofing on the newly exposed wall.
Recent work
The underpinning sequence
How Footing Underpinning Gets Done in Gatineau
Structural engineer designs the work
The engineer specifies footing depth, width, materials, and the exact sequence in which bays are excavated and poured so the building stays supported at every stage.
Excavate one bay at a time
Following the engineered sequence, a single bay is dug out to the new footing depth. Adjacent bays remain undisturbed, so the building is always supported on both sides of the open section.
Form and pour the new footing
The deeper or wider footing section is formed, reinforced with rebar, and poured in concrete. The new footing is keyed or pinned to the existing footing above so load transfers cleanly.
Cure and move to the next bay
The concrete cures to full strength, then the next bay in the sequence is excavated and poured. This cycle repeats until the entire footing has been extended to the engineered depth or width.
Why bays matter
Numbered Bays Keep the Building Supported Throughout
The temptation is to think of underpinning as digging out the entire footing and replacing it. That would collapse the house. Bays are the reason underpinning works. At any moment, only a small section of footing is exposed and unsupported, while the rest of the footing is bearing the full load of the building above.
The engineered sequence is also why underpinning cannot be improvised. Skipping ahead, excavating two adjacent bays at once, or pouring without proper curing time risks settlement during the work itself. We follow the sequence exactly as designed, and we apply foundation waterproofing to the newly exposed wall before backfilling. The written estimate includes the full timeline so you can plan around the work.
Bay sequences, basement deepening, additions, and when underpinning is the right choice.
If settlement keeps happening after repair attempts, if the cracking is at the footing rather than just in the wall, if the soil bearing capacity has changed, or if you are adding load or lowering the basement floor. The assessment will tell us which is right.
Yes. The bay sequence means only a small section of footing is unsupported at any time, and the rest is bearing the load. Most homeowners stay in their homes through underpinning; we let you know if your situation is the exception.
Yes, that is one of the main uses. Lowering a basement floor below the existing footing requires the footing to be extended downward in bays; once underpinned, the floor can be excavated to the new depth and a new slab poured.
Only when the new load on the existing footing exceeds what the footing was sized for. The structural engineer for the addition determines that; we underpin the existing footing to the engineered detail when required.
Several weeks for a typical residential underpinning, because each bay has to be excavated, formed, poured and cured before the next bay starts. The full schedule is in the written quote so you can plan around it.
Homeowner reviews
What Gatineau Homeowners Say About Their Underpinning Projects
We added a second storey and the engineer said underpin. Gatineau Concrete did the sequence by the book, addition went on top, no settlement since. Done right.
T. J.
Gatineau
★★★★★
Settlement that two other contractors had tried to fix as wall cracks was actually a footing problem. Underpinning solved it. Cracks haven't moved since.
N. K.
Ottawa
★★★★★
Basement deepening project, underpinning first, then the new lower slab. Headroom we wanted, structure stronger than before. Worth every cent.
U. O.
Kanata
★★★★★
Engineered, sequenced, communicated every step. Lived in the house through the whole project, never felt unsafe. Underpinning is a craft and these guys know it.
G. H.
Nepean
From the blog
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Practical reading on planning, finishes and caring for concrete in Gatineau.
Describe what is happening with the foundation, whether it is ongoing settlement, a planned addition, or basement deepening. We will assess it at no cost and provide a written quote with the full timeline.
