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\section{Institutional setting}
\label{sec:setting}
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\subsection{Residential assessment in Québec and the place of the cost approach}

Municipal assessment in Québec is governed by the \emph{Loi sur la fiscalité municipale} (RLRQ, c.~F-2.1). Section~14 requires the assessor to prepare a roll every three years for three consecutive fiscal years; section~43 defines the value to be entered as the \emph{valeur réelle}, « sa valeur d'échange sur un marché libre et ouvert à la concurrence, soit le prix le plus probable qui peut être payé lors d'une vente de gré à gré » between informed, unconstrained parties; and section~46 fixes the reference date for both the state of the unit and market conditions at 1~July of the second fiscal year preceding the first year of the roll. The roll therefore reports, for every unit, a total value and its land and building components as of a dated market-conditions reference; in our data this reference is 2022, 2023 or 2024 depending on the municipality's cycle.

The methods are prescribed by the \emph{Manuel d'évaluation foncière du Québec} (MEFQ), to which the Act's regulations refer. Part~3 of the manual, « Processus d'évaluation », has separate chapters for the measurement of market variation (3A), roll equilibration (3B), the comparison method (3C), the income method (3D), the cost method (3E) and the reconciliation of value indications (3F). Chapter~3E provides unit-cost schedules from which a \emph{coût neuf} is built from a base cost, together with annual \emph{facteurs de rajustement} published by the ministry with a 1~July reference date. The full text of Chapter~3E was not available to us; the description above rests on the manual's published structure and on the ministry's public page on adjustment factors, and the paper makes no claim about the detailed content of the schedules or of the depreciation tables. What matters for the design is that the roll's building value is produced within a cost-based mass-appraisal framework and then reconciled with market evidence, so that it is a professionally produced, dated indication rather than either a construction cost or a transaction price.

Professional appraisal practice in Québec is regulated by the Ordre des évaluateurs agréés du Québec, whose standards of practice we could not consult in their current edition; the Canadian Uniform Standards of Professional Appraisal Practice (CUSPAP 2024) and the International Valuation Standards effective 31~January 2025 are the national and international references. All three recognise the cost approach as one of three approaches and require that its inputs---land value, cost new, depreciation---be supported and that the approach's applicability be assessed; none of them contemplates the use of listing photographs as an input, which is the gap this paper documents rather than fills.

\subsection{The Vrai Prix data infrastructure}
\label{sec:vraiprix}

Vrai Prix is a research platform developed by the author that assembles three bodies of data. The first is the provincial assessment roll, published by the Ministère des Affaires municipales et de l'Habitation on Données Québec under a CC-BY~4.0 licence, with owner names, cadastre and mailing addresses redacted at source: 3.75~million units with address, coordinates, land-use code, year built, floor area, lot area, storeys, number of dwellings, and assessed land, building and total values with their market-conditions date. The second is the register of residential transfers since January 2021 (769\,333 transactions in the copy used here), linked to the roll unit. The third is a daily feed of for-sale listings from 67 broker and platform connectors operated by a companion platform, each listing carrying its photographs, free-text description, feature list and broker-entered structured fields, and matched to a roll unit by geocoding with a recorded match distance.

The Vrai Prix valuation engine, whose source we inspected in a verbatim copy dated 17~October 2026, combines a gradient-boosted hedonic model trained on the register with an adjusted-comparables estimate and reconciles the two with fixed weights; it also stores, for every evaluated listing, a production estimate labelled as a cost estimate whose generating code was not available to us during this study. Vrai Prix therefore provides the \emph{data substrate} of this paper---verified administrative fields, listing media and text, dated assessor values, and production estimates usable as external benchmarks---but \textbf{it does not contain the image-based cost approach studied here}. The extraction schema, the aggregation rules, the cost schedule, the depreciation model and the evaluation design were all developed for this paper and are released with it. Readers should not read the results as a validation of a deployed Vrai Prix component.