Foundation problems in Renfrew County range from minor shrinkage cracks to serious structural movement. The repair method must match the problem — using the wrong approach wastes money and may not solve the issue. This page explains the main repair methods available, when each is appropriate, and when a licensed structural engineer (P.Eng.) is required.
Crack Injection
Crack injection is used to seal cracks in poured concrete foundation walls. Two products are used depending on the situation:
Polyurethane Foam Injection
Polyurethane foam is injected under low pressure into a crack where it expands to fill the void and cure into a flexible rubber-like material. Because it remains flexible, it accommodates minor continued movement without re-cracking. It is the preferred method for cracks where water is actively entering, as it bonds to wet surfaces and seals the crack against future leakage.
Best for: Active water-leaking cracks; vertical and diagonal shrinkage cracks; situations where some future movement is anticipated
Epoxy Injection
Epoxy injection fills a crack with a rigid, high-strength adhesive that cures to a strength greater than the surrounding concrete. It restores structural continuity across the crack rather than just sealing it. Epoxy requires a dry crack to bond properly — it cannot be used for actively leaking cracks.
Best for: Dry structural cracks where restoring wall strength is the goal; hairline to moderate cracks showing no ongoing movement
When Crack Injection Is Not Enough
Crack injection does not address the cause. If a crack is caused by ongoing soil pressure, settlement, or structural movement, injecting it may seal the crack temporarily but will not prevent re-cracking or progression. Horizontal cracks, stair-step cracks in block walls, and cracks wider than 6mm should be assessed by a structural engineer before injection — they may indicate a problem that requires a different approach entirely.
Carbon Fibre Straps
Carbon fibre straps are used to stabilize bowing or inward-deflecting foundation walls caused by lateral soil pressure. They are bonded to the wall surface in vertical strips using structural epoxy and anchored to the floor system above. Carbon fibre is extremely strong in tension — it resists further inward movement effectively.
Key limitation: Carbon fibre straps hold the wall in its current position but do not push it back. If the wall has bowed 2 inches, it will remain at 2 inches — the strap prevents further movement. This is acceptable in most cases where the deflection is within code tolerance, but if restoration is needed, a wall anchor system is required.
Advantages: No excavation required; minimal disruption; typically completed in one day; durable long-term solution; no maintenance required once installed.
When a P.Eng. is required: A structural engineer should assess bowing walls before any repair is specified. They will measure the deflection, assess whether it is within acceptable limits, determine the cause, and confirm whether straps are appropriate or whether more intervention is needed.
Wall Anchor Systems
Wall anchor systems are an alternative to carbon fibre for bowing walls — with the added capability of gradual correction. A steel plate is attached to the foundation wall; a steel rod extends through the wall and the surrounding soil to a buried anchor plate set in stable soil well away from the foundation.
Once installed, the wall anchor can be tightened periodically — typically once or twice per year — to gradually draw the wall back toward its original position. This is a multi-year process: most engineers recommend small incremental adjustments to avoid inducing new cracking.
Best for: Bowing walls where the deflection needs to be corrected over time, not just stabilized; situations where the homeowner wants the option to restore the wall position
Wall anchors require excavation outside the foundation to place the anchor plates — a more disruptive installation than carbon fibre straps, but the correction capability may justify it.
Underpinning
Underpinning extends the depth of an existing foundation so it bears on more stable soil or rock below. It is used when the original foundation is too shallow, when soil beneath the footing has eroded or subsided, or when the basement is being lowered (bench or full underpinning for added headroom).
Mass Concrete (Pit) Underpinning
The most common method in Ontario for residential foundations. The contractor excavates in alternating sections beneath the existing footing (to maintain support during work), pours new concrete to the required depth, allows it to cure, then moves to adjacent sections. Each section is typically 0.9–1.5 metres wide. This is methodical, reliable work — but it is slow, labour-intensive, and requires a permit and structural engineer drawings.
Mini-Pile or Micro-Pile Underpinning
Where access is limited or soil conditions are variable, small-diameter steel piles driven beneath the existing footing can provide support without extensive excavation. Less common for residential work in Renfrew County but occasionally used in constrained situations.
When a P.Eng. is required: Always for underpinning. A structural engineer must design the underpinning sequence, specify depths and bearing capacity, and review or stamp drawings for building permit submission.
Helical and Push Piers
Pier systems are used when a foundation is settling due to inadequate soil bearing capacity and the goal is to transfer the load to deeper, stable soil or bedrock.
Helical Piers
Helical piers (also called screw piles) are steel shafts with helical plates that are driven into the ground by rotating — like a large screw. They can be installed from inside or outside a basement. Once the helix reaches competent soil or rock, the pier is connected to the foundation via a bracket. They are well-suited to Renfrew County conditions where competent bedrock is often reachable at moderate depth.
Push Piers
Push piers (resistance piers) are driven hydraulically into the ground using the weight of the structure as resistance. They are pressed segment by segment until refusal at stable soil or bedrock, then locked and used to lift and support the foundation. Push piers can sometimes lift a settled foundation back to its original elevation.
When a P.Eng. is required: A structural engineer should assess settlement and specify the pier type, spacing, and depth. Pier installation for structural foundation repair requires a building permit in Ontario.
Learn more: Foundation Repair Overview | Permits & Regulations