When a Neighbour's Regrading Flooded a Georgina Basement

The situation

Dimitri and Angela bought their Georgina home nine years ago. Dimitri works as a registered nurse; Angela works as a court clerk. Their half-acre lot backs onto a slightly higher property owned by Raymond, who had lived next door for over a decade without incident. That changed the spring after Raymond had his backyard regraded and a stone patio installed along the shared property line.

Within weeks of the landscaping work finishing, Dimitri and Angela started noticing standing water pooling against their foundation after every significant rainfall. By early summer, water was seeping into their basement through hairline cracks near the footing. They assumed it was an aging waterproofing membrane and spent several thousand dollars on a contractor who sealed the interior walls. The flooding came back with the next heavy rain.

It took a second, more determined round of investigation — including watching where the water actually pooled during a storm — before they suspected the problem wasn't coming from inside their own foundation at all. It was arriving from next door.

Dimitri and Angela had lived in the home long enough to know its normal drainage pattern, and this wasn't it. Before the landscaping next door, a moderate rainstorm left their backyard damp for an afternoon and nothing more. After it, the same storm left a visible sheet of water flowing toward their foundation wall and pooling in the low corner of the yard closest to Raymond's new patio. They raised it with Raymond directly first, informally, over a fence-line conversation. He was sympathetic but skeptical that his landscaping was the cause, and the conversation didn't go anywhere on its own.

What the review found

Dimitri and Angela retained a drainage engineer to assess the grading on both properties. The report was decisive. Raymond's landscaping contractor had raised the elevation of his backyard by regrading soil toward the shared property line, and the new patio's base had been built without any drainage allowance. Where the two yards used to slope gently away from each other, the regraded yard now sloped toward Dimitri and Angela's foundation, effectively engineering a channel for stormwater to run directly at their basement wall.

In Ontario, property owners have a general obligation not to alter the natural flow of surface water in a way that causes damage to a neighbouring property. That doesn't mean every drop of runoff crossing a property line is actionable — water naturally moves downhill, and some incidental runoff between neighbouring lots is normal and not compensable. What matters is whether a landowner has artificially changed the grading or drainage pattern and, in doing so, materially increased the volume or concentration of water reaching a neighbour's land. The engineer's report was able to show, with before-and-after grading measurements, that this is exactly what had happened here.

The report also estimated the cost of the damage: repairing the foundation cracks, replacing damaged drywall and flooring in the finished basement, and installing a permanent drainage solution — a below-grade swale and catch basin along the property line — to stop the problem from recurring. Combined with the diminished value of a home with a documented water-intrusion history, the couple's total exposure sat well into six figures, more than what Small Claims Court could resolve. This was a Superior Court matter from the outset.

Before filing anything, our team wrote to Raymond directly, attaching the engineering report and inviting him to have his own expert review it. He did. His engineer largely agreed with the grading analysis but disputed the full damage estimate, arguing that some of the basement finishes were already near the end of their useful life and that the couple was, in effect, asking him to pay for a full basement upgrade rather than a repair.

What we did

1. Documented the damage before any repairs began. Photographs, moisture readings, and the original waterproofing contractor's invoice all went into the file early, so the timeline of when the flooding started — right after the regrading — was clearly on the record rather than reconstructed from memory later.
2. Commissioned an independent grading survey. Rather than relying on assumptions about where the water was coming from, we had the engineer produce elevation measurements comparing the current grading to municipal records and satellite imagery of the yard before the landscaping work. This turned a dispute that could have come down to conflicting memories into one anchored in measurable fact.
3. Sent a formal demand letter with the supporting report attached. This gave Raymond and his insurer a clear, evidence-backed basis to evaluate the claim before litigation costs started accumulating on either side, and it started the clock on a reasonable response window.
4. Filed a Statement of Claim in the Superior Court when the demand went unanswered on the core repair issue. The claim sought the cost of remediation, the permanent drainage fix, and damages for the diminished use of the basement during the period it couldn't be safely finished or rented as a secondary suite, which the couple had been planning before the flooding began.
5. Engaged in examinations for discovery focused narrowly on causation. Rather than litigating every dollar of the damage estimate, we concentrated the discovery process on establishing, on the record, that the regrading — not pre-existing foundation wear — caused the water intrusion. Once that point was well established through Raymond's own expert's concessions, the case shifted from a question of fault to a question of value.
6. Proposed a mediated settlement once liability was effectively conceded. With causation no longer seriously contested, continuing to trial risked significant additional cost for a dispute that had narrowed to a disagreement over the value of basement finishes nearing the end of their life. A private mediation was the more proportionate route.

The outcome

The mediation produced a negotiated settlement rather than a clean win for either side. Raymond agreed to pay for the full cost of the permanent drainage fix — the swale and catch basin — since that was squarely his responsibility to correct going forward, and to cover the structural foundation repair in full. On the basement finishes, the two sides split the difference roughly down the middle, reflecting the legitimate point that some of the flooring and drywall had genuine pre-existing wear that the flooding accelerated rather than solely caused.

Dimitri and Angela recovered a substantial majority of what the engineering report had estimated as their total loss, but not all of it, and the process took close to two years from the first flooded basement to a signed settlement. They didn't get compensation for the rental income they had hoped to earn from a finished basement suite, since that plan was never formalized before the damage occurred and was too speculative to prove as a loss. Raymond, for his part, avoided a trial where his own expert's concessions on causation would likely have exposed him to the full claim, plus costs.

The drainage fix was completed the following spring. Two full rainy seasons later, the basement has stayed dry. Dimitri and Angela still consider the outcome a fair one, if a hard-won one: it took a formal engineering report, a filed claim, and nearly two years to get there, for a problem that traced back to a single landscaping decision made over the course of a few weeks. Raymond, for his part, has told them he now asks any contractor working on his property for written confirmation of how a project will affect drainage along the property line before work begins.

What you can learn from this