Background
Ming Sun Benevolent Society and the appellants owned adjacent buildings on Powell Street in Vancouver, separated by approximately two inches. The appellants’ building had a sloped roof whose valley flashing was intended to direct rainwater away from the narrow space. In 2013, brick veneer on Ming Sun’s east wall detached and fell onto the neighbouring building. The resulting damage prompted the City of Vancouver to order the appellants’ building demolished and to declare Ming Sun’s building unsafe; Ming Sun’s building was eventually demolished as well.
The parties advanced competing explanations for the collapse. Ming Sun alleged that the appellants failed to maintain the valley flashing, allowing water to deteriorate the wall. The appellants blamed inadequate maintenance of Ming Sun’s building. The trial judge accepted Ming Sun’s expert evidence and found that the veneer would not have detached but for water entering through leaks, discontinuities, or overflow in the poorly maintained flashing.
The trial judge held the appellants liable in negligence and nuisance, dismissed their counterclaim, and assessed Ming Sun’s losses at $1,537,470.26, subject to a 15% reduction for contributory negligence. Ming Sun was contributorily negligent because its directors knew water was entering through the deteriorated flashing but did not ask the appellants to repair it or otherwise address the problem.
The Court’s Holding
The Court of Appeal dismissed the appeal. It held that the trial judge committed no reviewable error in admitting and relying on Ming Sun’s expert evidence, excluding a late supplementary report from the appellants’ expert, or refusing permission to call an unlisted City inspector. The finding that poorly maintained valley flashing was the principal source of water ingress and the but-for cause of the collapse was reasonably available on the evidentiary record.
The Court also upheld the findings of negligence and nuisance. An adjoining owner in these circumstances was required to install, inspect, maintain, and, when necessary, replace a mechanism that prevented rainwater from its sloped roof from damaging neighbouring property. The trial judge correctly found that the collapse and the ensuing closure, lost rental income, vandalism, and eventual demolition were reasonably foreseeable consequences of the appellants’ breach.
The 15% contributory-negligence allocation was upheld because the trial judge properly compared the parties’ relative blameworthiness. The mitigation defence was not adequately pleaded and, in any event, the findings showed that Ming Sun acted reasonably after the collapse. The appellants’ counterclaim also failed because their theory depended on Ming Sun’s maintenance failures being the cause of the collapse, a theory the trial judge had rejected.
Key Takeaways
- An adjoining property owner may be liable in negligence and nuisance when poorly maintained roof drainage directs water onto neighbouring property and causes structural damage.
- Appellate disagreement with a trial judge’s weighing of competing expert and lay evidence does not establish palpable and overriding error.
- Contributory negligence turns on relative fault in protecting one’s own interests, while mitigation concerns avoidable consequential loss and should be specifically pleaded.
Why It Matters
The decision confirms that responsibility for building components designed to control runoff can carry substantial consequences extending beyond the immediate physical damage. Where the resulting chain of losses is reasonably foreseeable, liability may encompass closure, lost income, subsequent deterioration, and demolition.
It also underscores the limits of appellate review. A lengthy catalogue of alleged errors will not justify intervention when it amounts to rearguing factual issues that the trial judge resolved on an adequate evidentiary foundation.