Who Is Responsible For Condo Walls, Ceilings, And Floors? Alberta Court Of Appeal Clarifies In Aubin v Condominium Plan No 862 2917

• Published date: 12 November 2025
• Subject Matter: Litigation, Mediation & Arbitration, Real Estate and Construction, Trials & Appeals & Compensation, Construction & Planning, Real Estate
• Law Firm: Miller Thomson LLP
• Author: Mr Robert Noce, Michael Gibson and Ryley Schmidt

What's the issue?

It is often said that good fences make good neighbours.¹ But condominium living often raises one key question: where does your unit end, and the common property begin? This boundary is critical because it determines who - owner or condominium corporation - is responsible for potential costly repairs and upgrades.

The Alberta Court of Appeal's recent decision in Aubin v Condominium Plan No 862 2917 ('Aubin') offers new guidance, with implications for hundreds of condo plans across the province.

What is the Aubin case about?

This case involved a unit owner who owned a ground-floor unit in a high-rise condominium building. The unit itself shared a common wall with the condominium's common property lounge, which was used for board meetings and social functions, as may be scheduled by any unit owner.

In 2019, the unit owner brought a claim against her condominium corporation, alleging that the condominium corporation had a duty to improve the sound transference between the common area lounge and her unit, on the other side of the wall. The issue, as explained by the unit owner in her own evidence, was that she could hear noise coming from the lounge when it was in use, and that the noise was allegedly interrupting her daily life.

What are condominiums in legal terms?

Condominiums can be many things:

• apartment-style high-rise buildings;
• commercial warehouses;
• townhouses; and even
• bare parcels of land.

Condominiums are not a specific type of construction, nor are they just a form of collective living. Condominiums are in actual fact a form of collective property ownership. That is, they are a legal construct to facilitate the shared ownership of real property. Through that construct, unit owners own and are responsible for their private units. Like any property owner, unit owners must maintain their unit, comply with the applicable rules and community standards that govern their community, and are liable when they cause damage to neighbouring property owners.

Condominium unit owners also own a proportionate share of the common property in their condominium. A 'condominium corporation' is the statutory body that comes into being when a condominium plan is registered to manage the maintenance of the collective common property interests of all of the owners.

Indeed, the condominium context creates a further layer of complexity, given the competing interests that must all be balanced for peaceful co-existence and shared property ownership. The responsibility of balancing the private and communal interests of the unit owners falls to the condominium's elected board of directors, who are generally entitled to deference in the exercise of their discretion in managing the shared property of all unit owners in their collective best interests to, hopefully, achieve the greatest good for the greatest number.² On this point, when reviewing a condominium board's decision, a court's first question is usually to ask whether the directors acted honestly and in good faith and exercised the care, diligence and skill that a reasonably prudent person would exercise in comparable circumstances.³

What was at stake in the Aubin case?

In Aubin, the building was built in approximately 1973. Neither the condominium corporation nor the unit owner played any part in the construction and design of the wall and there was no evidence that the wall was not otherwise structurally sound or had ever been renovated or altered since the time of the building's original construction. The Court had to decide who is responsible for the wall: the owner or the condominium corporation?

How does the Condominium Property Act define boundaries?

Defining the boundary became critical to determining who, as between the unit owner and the condominium corporation, was responsible for improving the sound transference that was noted to be below applicable building code standards.

Section 8(1)(f) of the Condominium Property Act (the 'CPA') specifically requires that every condominium plan in Alberta must contain a description setting the boundary between the units and common property. Appreciating that condominium plans are drafted by land surveyors, and not lawyers, s. 9 of the CPA sets certain default boundaries to clarify the legal boundary between units and common property. This facilitates a purposive interpretation of the condominium plan documents, akin to the interpretation of municipal planning documents and statutes more broadly.

In this regard, the statutory default under s. 9(1) provides:

9(1) Unless otherwise stipulated in the condominium plan, if

(a) a boundary of a unit is described by reference to a floor, wall or ceiling, or

(b) a wall located within a unit is a load bearing wall,

the only...