Rebuilding the Numbers Behind a Shared Wall Dispute

The situation

'How can we be the ones paying for damage Farid caused?' Wilson asked on the phone, before either he or his sister Jamal had seen a single document explaining how the condominium corporation had arrived at the number on their special assessment notice.

Wilson, an air traffic controller, and Jamal, a veterinarian, co-owned a condominium unit in London that they had bought together several years earlier, in the high six figures, intending to hold it as a long-term property for their aging parents to eventually live in. Both of them worked demanding, unpredictable schedules, and the unit had largely run itself for years, generating no more paperwork than the occasional common expense increase. The unit shared a load-bearing wall with the neighbouring suite, owned by Farid, and it was that wall, part of the building's common elements under the condominium's registered declaration, that became the source of the dispute.

Farid had renovated his unit roughly a year earlier, including work that altered the shared wall -- removing a section of drywall and some interior blocking to widen a doorway, without seeking the condominium corporation's prior approval for the change, as the declaration required for any alteration touching a common element. The alteration went unnoticed by the corporation for months, until a routine reserve fund inspection turned up cracking and settling on Wilson and Jamal's side of the same wall, serious enough that the corporation ordered structural repairs.

The corporation issued a special assessment to cover the repair, and the notice named Wilson and Jamal's unit as bearing a share of the cost, alongside Farid's. To the siblings, this felt backwards: the alteration had happened entirely on Farid's side, without their knowledge or consent, and the resulting damage had shown up on their side of a shared structure they had never touched. The assessment notice offered a total figure and a per-unit share but no breakdown of how the corporation's engineer or property manager had divided the cost between the two units, or between Farid individually and the ownership as a whole.

Wilson and Jamal's first instinct, understandably, was that they were being billed for someone else's mistake. Getting to the actual answer meant finding out, in detail, how the number on the assessment notice had been calculated in the first place.

What was actually at stake

What was actually at stake was not just the dollar figure on the notice, but which of two very different frameworks applied to it: the ordinary rule that common element repairs are shared among all owners in proportion to their unit's designated share, or the narrower rule that lets a condominium corporation charge the cost of repairing damage back to the specific owner who caused it, when that owner altered a common element without authorization.

Under the Condominium Act, 1998, corporations are generally required to maintain and repair the common elements, and the cost of that maintenance is normally spread across all owners as part of common expenses, proportional to each unit's share, exactly as the corporation had done with Wilson and Jamal's assessment. But that general rule has a well-established exception: where damage to a common element is caused by an owner's own act, including an unauthorized alteration, the corporation can typically pursue that owner directly for the cost of repair, rather than spreading it across everyone. Declarations commonly include language allowing the corporation to charge back costs in exactly this situation.

The question for Wilson and Jamal was whether the wall damage fell into the general category or the chargeback category, and the honest answer was that nobody, including the corporation itself, could say for certain without digging into how the repair estimate had actually been built. The property manager's notice bundled a general reserve-fund-related repair together with a portion of cost plausibly tied to Farid's alteration, without separating the two, and the engineer's report, once obtained, described both an underlying settling issue affecting the wall generally and a specific area of stress consistent with the section Farid had altered.

That ambiguity mattered financially. If the full cost could be attributed to Farid's unauthorized alteration, the corporation could reasonably have charged it entirely to him, and Wilson and Jamal's assessment should have been zero. If only part of the damage was attributable to Farid and the rest reflected ordinary wear the corporation would have had to repair regardless, then some shared cost across all affected owners, including Wilson and Jamal, was legitimate. The stakes were not abstract: the difference between the two scenarios was several thousand dollars, and resolving it required someone to separate the corporation's bundled number into its actual components before anyone could say what Wilson and Jamal genuinely owed.

What we did

1. Requested the structural engineer's full report and the contractor's itemized repair invoices, rather than relying on the summary figure in the assessment notice, because a one-line total gives no way to tell how much of the cost was tied to Farid's alteration and how much was ordinary common element wear the corporation would have had to fix regardless. The property manager was initially reluctant to release the underlying invoices, and it took a written request citing Wilson and Jamal's right to review supporting documentation before the full package arrived.
2. Rebuilt the cost allocation from the underlying invoices, line by line, separating charges for work clearly tied to the altered section of the wall from charges for broader stabilization work the engineer had recommended independent of the alteration, since the property manager's original notice had simply added everything together into a single number without any explanation of how the split had been reached.
3. Found a double-counted line item in the process, where a mobilization charge from the contractor had been applied to the total twice, once in the general repair estimate and once in a supplementary invoice, inflating the overall assessment before it was even divided between owners. Neither the property manager nor the board had caught the duplication, since neither had reviewed the two invoices side by side.
4. Recalculated what portion of the corrected total was properly attributable to Farid's unauthorized alteration versus what portion reflected pre-existing wear, using the engineer's own description of the two types of damage to draw the line rather than guessing at a fair-sounding split. This distinction was the crux of the file, since it determined whether Wilson and Jamal owed anything at all beyond the share every owner would have paid regardless of Farid's renovation.
5. Presented the reconstructed accounting to the property manager and board in writing, showing both the double-counted charge and the proposed division between chargeback cost and shared common expense, so the correction was grounded in the corporation's own documents rather than a dispute about fairness. Framing the request around the corporation's own invoices, rather than an outside opinion of what seemed fair, made it far harder for the board to simply decline.
6. Negotiated a revised assessment with the board, reducing Wilson and Jamal's share to reflect only the portion of the corrected total tied to genuine common element wear, while the corporation issued a separate, larger chargeback directly to Farid for the alteration-related cost. Splitting the assessment this way meant the corporation still recovered its full repair cost, just from the owner whose alteration had actually caused the larger share of the damage.
7. Confirmed the revised assessment notice in writing before Wilson and Jamal paid anything, making sure the corrected figures, not the original bundled estimate, were what actually appeared on their account, and that the correction was reflected in the corporation's own records, not just in the correspondence. This step avoided a common gap where a verbal agreement to reduce a charge never makes it onto the actual ledger, leaving the original bundled figure enforceable.
8. Advised Wilson and Jamal on what to watch for going forward, including asking to see engineer's reports and contractor invoices directly rather than relying on summary notices whenever a shared structural issue arises, since the original error would likely have gone unnoticed without that underlying detail, and it is unlikely to be the last shared repair the building faces. Older buildings tend to generate a steady stream of shared repairs, and the habit of asking for source documents will keep paying off long after this particular dispute is closed.

The outcome

Wilson and Jamal ended up paying a reduced special assessment, roughly a third of the original figure, once the corporation separated the double-counted charge and reallocated the alteration-related cost directly to Farid. That is a real reduction, and it is fair to call the accounting correction a success on its own terms. It is not, however, a clean win, and the file is better described as a loss contained than a loss avoided.

The siblings still paid something. Part of the wall's structural issue, once properly separated from the alteration-related damage, was genuine common element wear that the corporation would have had to repair and assess to all affected owners regardless of what Farid had done, and Wilson and Jamal's unit was one of the units sharing that legitimate portion. No amount of reconstructing the accounting could turn that portion into someone else's bill.

There was also a cost to the process itself, one that does not show up on the assessment notice: months of back-and-forth with the property manager, an engineer's report that took weeks to obtain, and a period during which Wilson and Jamal did not know what they actually owed. That uncertainty is a real cost for two owners managing a shared property from busy, unrelated careers, even if it never appeared as a line item. Their relationship with Farid, who remained their neighbour throughout, stayed civil but noticeably cooler than before the dispute began.

What the file demonstrates is how much a bundled number can hide, and how much of a difference it makes to insist on the underlying documents before paying a shared assessment tied to another owner's actions. Wilson and Jamal did not recover everything they initially believed they were owed, but they paid only what the corrected accounting actually supported, and Farid, not the siblings, bore the larger share of a repair his own alteration had caused.

What you can learn from this