Executive Summary: Key Legal and Evidentiary Issues

• Allocation of responsibility under the Civil Code of Québec’s legal warranty of quality regime for defective thermos glazing supplied for a military building project
• Characterisation of the defects as both functional and conventional vices because the glazing prevented occupants from seeing out and did not meet the specific “one-way mirror” security requirement
• Application of the presumption of knowledge against a professional seller/manufacturer and its failure to rebut that presumption in the absence of expert evidence on conformity and cause of the defect
• Weight given to project documents and testimonial evidence (architect, contractor, subcontractor, manufacturer’s representative) to establish the client’s requirement for an exterior mirror effect and the manufacturer’s awareness of that requirement
• Assessment of liability for additional deficiencies (bubbles, scratches, discoloration) following the agreed solution of inverting the glazing and the manufacturer’s unsuccessful, largely unsupervised cleaning “solution”
• Quantification of damages flowing from the defects, including contractual holdback and additional insurance costs, and determination of the date from which legal interest and the additional indemnity begin to run

Facts of the case

The dispute arises from remedial construction works at Building M-10, located at the Garnison St-Hubert military base in Québec. Canada’s defence construction agency awarded a contract dated 10 August 2016 to Roland Grenier Construction ltée, which acted as the general contractor for repairs to the building’s exterior envelope, including the roof, walls and windows. As part of this project, Roland Grenier subcontracted Qualum inc. to fabricate the aluminium window frames for 158 windows. Qualum, in turn, retained Multiver ltée to manufacture and supply sealed thermos glazing units that would be installed within Qualum’s frames.
A key security requirement for this military facility was the installation of glazing with a mirror effect on the outside. The intent was to prevent persons outside the building from seeing in, in order to reduce espionage risks, while still allowing occupants to see out. This requirement was specified in the written specifications dated 29 November 2016, which stipulated that the mirror effect had to be on the exterior side of the glazing. The project architect, Stéphanie Vallière, also testified that the same external mirror requirement was consistently maintained throughout the project and was clearly communicated to all stakeholders, including Multiver’s representative.
In January 2017, the architect personally discussed the security-driven mirror requirement with Multiver’s representative, Chantale Robichaud, and followed up in subsequent exchanges. Multiver submitted its quotation on 8 February 2017. According to Ms. Robichaud’s evidence, this quotation reflected the client’s requirement, and she included a hand-drawn sketch showing the “faces” of the glazing and indicating where the mirropane film—the product that creates the reflective effect—was to be placed. The shop drawings, Qualum’s purchase order and Multiver’s internal order entry all repeated the same indications as Multiver’s quotation regarding which faces of the glazing would receive the mirropane film.
However, the physical sample Multiver supplied directly to the architect used a different configuration of faces than that shown on Multiver’s quotation. According to the architect, this sample complied with the security requirements. That discrepancy later became important when the court examined where the fabrication error likely occurred.

Defective glazing and immediate consequences

Multiver delivered the glazing units directly to the site on 26 September 2017. The very next day, those on site noticed that the glazing produced the opposite mirror effect to what had been requested. Instead of providing a one-way view from the interior outwards, the reflective effect was on the interior side. People inside the building could not see outside, while the outside view was not blocked in the way the client required. The court described this as a serious vice both functionally—because the windows could not serve their normal use of allowing occupants to see out—and conventionally, because they failed to meet the specific, security-driven usage identified by the client.
The parties promptly engaged in discussions to find a solution. After seeking and receiving confirmation from Multiver and from the manufacturer of the mirropane film (Pilkington North America Inc.), they agreed to invert the glazing units so that the mirropane film would face the exterior, thereby producing the desired external mirror effect. On this basis, the works were completed, with the end of works recorded as 13 December 2017.

Emergence of further defects and attempted remedial measures

On 22 January 2018, roughly a month after completion, representatives of all stakeholders inspected the building and identified new defects affecting the mirropane glazing. They observed bubbles, scratches and significant discoloration in the mirropane units; a report dated 27 January 2018 recorded that 134 of the 158 units exhibited these problems. The evidence did not ultimately clarify what became of the installed mirropane glazing after this point, but it was clear that the units suffered substantial deterioration in a very short period.
On 6 February 2018, Multiver removed two glazing units and returned them to its factory for analysis. These units were cleaned using a specific product containing cerium oxide. After cleaning, they were reinstalled on the building. Multiver then provided Roland Grenier with a “zip-lock” bag containing a powder identified as the required cleaning product, along with a few names of cleaning companies, but without confirming whether those companies had the capacity or expertise to clean mirropane glazing. The owner later issued a final notice of non-conformity to Roland Grenier, stating that cleaning the exterior faces of the glazing using a specified product and procedure had proven inconclusive and that the defects persisted.
Because of the persisting deficiencies, the client retained a contractual holdback of CAD 76,347.99 to address the glazing problems. Roland Grenier also had to pay an additional CAD 3,724.53 in insurance costs to keep the site insured after the works were completed. It therefore claimed total damages of CAD 80,072.52 from Multiver.

Legal framework: Legal warranty of quality and types of vices

The parties agreed that the applicable legal regime was the Civil Code of Québec’s legal warranty of quality in respect of sellers and manufacturers, rather than the contractual regime for a contract of enterprise. The court relied on articles 1716 and 1726 C.c.Q., which impose on the seller a duty to warrant that, at the time of sale, the property is free from latent defects that render it unfit for its intended use or so diminish its usefulness that the buyer would not have purchased it or would have paid a lower price had the defect been known.
The court first considered whether the glazing was affected by a latent defect. A defect, under the Civil Code, is any deficiency that renders the thing unfit for its intended use. Jurisprudence distinguishes three broad categories of vices: material vices (a specific, physical defect such as breakage on delivery), functional vices (defects in the design or functioning of a product) and conventional vices (where the product fails to meet a particular, expressly communicated purpose or usage). A functional vice is established when the product cannot, in whole or in significant part, serve its intended use according to an objective standard, whereas a conventional vice is assessed in relation to the special purpose made known by the buyer. The categories may overlap, and a defect may be both functional and conventional.
To invoke the legal warranty, a buyer must show that the alleged defect is hidden, sufficiently serious, existed at the time of sale and was unknown to the buyer. Once a defect is established, the court turns to the seller’s or manufacturer’s responsibility. For a professional seller or manufacturer, the law presumes knowledge of the defect where the buyer proves that the product malfunctioned or deteriorated prematurely compared to identical or similar products. This presumption shifts the burden: the professional can only escape liability by proving that the malfunction or premature deterioration resulted from improper use by the buyer, the fault of a third party or force majeure. A manufacturer, who controls both the materials and the labour in production, is treated as the ultimate expert and is subject to the strictest presumption and the highest duty to disclose latent defects.

Application of the legal warranty and presumption of knowledge

Multiver conceded that, as manufacturer of the glazing units, it was a professional seller. The court likened the situation to the Supreme Court of Canada’s ABB v. Domtar decision, noting that the alleged defect here was both functional and conventional: the glazing did not satisfy the specific external mirror requirement, and it did not functionally allow building occupants to see outside. As a result, if the presumption of knowledge applied, Multiver would be liable not only to restore the price but also to compensate the buyer’s loss, and could not rely on any clause purporting to limit its liability.
Multiver argued that the delivered glazing fully complied with the contractual documents—its quotation, Qualum’s purchase order and shop drawings approved by the architect and Roland Grenier—and that the internal mirror effect was therefore the result intended by the parties. The court rejected this argument on both evidentiary and logical grounds. First, Multiver presented no expert evidence and no fact witness who could confirm the precise composition of the delivered glazing units or definitively tie them to the technical details in the shop drawings and quotations. Even if one assumed conformity with its own documents, those documents themselves were based on information Multiver had provided, and they did not override the clearly established requirement that the mirror effect be on the exterior for security reasons.
Testimony from all key actors, including Multiver’s own representative Ms. Robichaud and Qualum’s representative Claude Tremblay, confirmed that the client always required an exterior mirror effect. The architect’s evidence and the written specifications were aligned with this requirement. The court found it implausible, on the evidence and in light of the project’s military context, that the client would ever have intended to install 158 windows through which no one inside the building could see out. The president of Multiver, who suggested such a scenario was possible, lacked credibility, having had minimal involvement in the project and being unable to cite any similar example from decades of industry experience.
The court concluded that Multiver, as expert manufacturer, had been fully informed of the client’s requirements and had itself proposed the thermos composition and location of the mirropane film. The handwritten sketch in Multiver’s quotation underpinned the later shop drawings, orders and internal documentation. Nevertheless, the finished product did not deliver the required exterior mirror effect; an error occurred somewhere in fabrication, whether in the configuration of the glass faces or in applying the mirropane film. Even though the precise point of error could not be pinpointed, the undisputed fact remained that the intended reflective effect was not achieved. On that basis, the court found that the glazing suffered from a serious functional vice (preventing normal outward visibility) and a serious conventional vice (failing to meet the security-related, specific use made known to the manufacturer). The presumption of knowledge therefore applied, and Multiver’s liability was engaged.

Liability for the inversion solution and subsequent deterioration

Having established the initial vice and the presumption of knowledge, the court turned to whether Multiver could avoid liability for the subsequent deterioration—bubbles, scratches and discoloration—that arose after the parties agreed to invert the glazing so that the mirropane film faced outward. Multiver contended that it had not decided on inversion; it merely relayed technical assurances from Pilkington and others, while Qualum, Roland Grenier and the owner made the final decision. It also pointed to warnings from Pilkington about the need for more frequent and careful cleaning when mirropane is installed on the exterior, and argued that Multiver was not a cleaning company and had no duty to carry out cleaning itself.
The court was unpersuaded. It held that Multiver not only participated in the decision to invert the glazing but was under a duty to remedy the original vice in its product. The decision to invert the units was taken in reliance on Multiver’s confirmation, as the glazing expert, that inversion would not affect the ten-year warranty, would not be prohibited by any technical limitation and would achieve the required mirror effect. In reality, only a few weeks after installation, most units displayed serious new defects, including marked discoloration. The court observed that the maintenance difficulties and exposure to the elements inherent in putting mirropane on the exterior had been anticipated in earlier communications between the architect and Multiver; they had originally decided to install the mirropane on the interior precisely to avoid such maintenance problems.
The court also found Multiver’s evidence on cleaning insufficient. No witness who actually performed the factory cleaning of the two test units testified, and the owner’s formal notice of non-conformity later confirmed that the recommended cleaning method did not resolve the defects. Instead of undertaking or at least supervising a structured cleaning programme, Multiver simply handed over a bag of powder with minimal instructions, effectively declining to accept responsibility for remediation. In these circumstances, the court held that Multiver failed to rebut the presumption of knowledge and had not established any of the recognised exonerating causes (improper use by the buyer, third-party fault or force majeure). The glazing remained affected by a serious vice even after inversion, largely due to discoloration that Multiver did not correct.

Assessment of damages and determination of interest

Turning to quantum, the court noted that the damages claimed by Roland Grenier were reasonable and essentially uncontested; Multiver disputed liability but did not seriously challenge the figures. The claimed loss comprised (i) the CAD 76,347.99 contractual holdback the owner retained specifically to address the glazing deficiencies, and (ii) CAD 3,724.53 in additional insurance premiums to keep the project insured beyond the formal end of the works. Together, these items totalled CAD 80,072.52, and the court found that both were a direct consequence of the vices affecting the glazing manufactured by Multiver. Because Multiver was a professional seller presumed to know of the defects in its products, it could not invoke any clause limiting its liability or the damages payable.
The remaining issue was the date from which legal interest and the additional indemnity should run. Roland Grenier argued for 13 December 2017, the end of the works, while Multiver suggested the date of a formal notice of default sent on 2 October 2020. The court instead chose 9 November 2018, the date of the owner’s official notice of non-conformity addressed to Roland Grenier. Analysing articles 1617 and 1594–1597 C.c.Q., the court concluded that Multiver was in default “de plein droit” once it clearly manifested its refusal to perform its obligations under the legal warranty. Evidence showed that, after the two units were removed and analysed in early February 2018, Multiver informed Roland Grenier that it would not participate in the cleaning process. Although the precise date of that refusal could not be established, the court adopted the date of the owner’s formal non-conformity notice as a conservative marker of when the failed cleaning process and Multiver’s refusal to properly remedy the situation were evident.

Ruling and outcome

In its final judgment, the Superior Court of Québec held that the thermos glazing supplied by Multiver was affected by serious functional and conventional vices, that Multiver, as a professional manufacturer, was presumed to have known of those vices, and that it failed to rebut that presumption or demonstrate any exonerating factor. The court further found that Multiver bore responsibility not only for the initial failure to deliver the required exterior mirror effect, but also for the subsequent defects arising after the inversion of the glazing and the inadequate cleaning solutions it proposed and failed to implement.
Accordingly, the court condemned Multiver ltée to pay Roland Grenier Construction ltée—the successful party in the proceedings—CAD 80,072.52 in damages, corresponding to the owner’s retained contractual holdback and the additional insurance costs, together with legal interest and the additional indemnity from 9 November 2018, plus costs of the action, the exact amount of which cannot be determined from the judgment.