Can you sell a house with pyrite in Montreal?

Can you sell a house with pyrite in Montreal?

Yes. No page cited here forbids the sale of a house because pyrite is in the stone fill under the slab, or because that fill can swell. What the sale does not skip is saying what you know. A defect the buyer has been told about is not a hidden one.

The OACIQ page on risk zones is written for a brokerage sale. It tells the broker what to say to a selling client and to a buying client. It does not say the sale of the house is forbidden. A sale with no broker does not use that page as a listing rule. How that sale runs is How do you sell a house without a real estate broker in Quebec?.

What do the official pages say pyrite is, and how does it show up?

The OACIQ describes pyrite as an iron sulphide molecule in the stone fill used in construction. It may be found around foundation drains and under the concrete slabs of the cellar or the garage. Under certain conditions it can oxidize and produce a sort of white powder that swells, lift the slab, and produce cracks in the foundation and partitions. These problems may appear several years after construction. The English page says issues have been identified in 91 cities of the Greater Montreal area. The French public page says problems have been recorded in the cities of that region, and it does not repeat the number 91, so this page does not treat 91 as a count of houses. Both pages name the highest-risk areas as the South Shore, from Châteauguay to Varennes and from the St. Lawrence River to the Richelieu River, the east end of Montreal, including Rivière-des-Prairies, Pointe-aux-Trembles and Repentigny, and the West Island, including Lachine, Dorval, Dollard-des-Ormeaux, Pointe-Claire, Kirkland, Pierrefonds-Roxboro and Beaconsfield (High-risk areas for pyrite).

The Régie du bâtiment du Québec describes the same mineral in its own words. It says pyrite is a mineral found in stone that produces sulphuric acid when it oxidizes in contact with humidity and oxygen, and that, when this happens under a foundation, it can cause the concrete slab to heave and crack (Pyrite et pyrrhotite, page in French). That is the Régie’s sentence. It is not a finding about one house.

The preamble of BNQ 2560-510, the 2022 standard on how the swelling-potential test is applied, describes the reaction rather than one street. It says swelling of granular backfill, or of rock, under concrete slabs comes from chemical reactions involving minerals in the materials, more specifically iron sulphides, and it names pyrite and pyrrhotite among them, together with the carbonates present, producing a crystallization of sulphates and then swelling. It says the reaction is influenced by clay minerals, grain size, the water content of the materials and temperature, and that the thickness of the backfill in place is a determining factor. It says the swelling creates pressure under the concrete slabs, which lift and crack, and that in some more severe cases lateral pressures appear and crack the foundation walls, generally in parts of a building where the backfill is above the footings, such as garages or parts of the ground floor. It also says some slab heave has been tied to swelling of the rock in place, not to the granular backfill. It says sulphate swelling tied to backfill can be present anywhere, that cases have been recorded in several regions of Quebec, and that a significant number of cases has been observed in Greater Montreal, particularly on the South Shore. It says a list of quarries at risk is hard to draw up, because of the number of production sites. This page does not add a count (BNQ 2560-510/2022, summary, page in French). A crack, water, or clay is a wider file (Can you sell a house with foundation problems in Quebec?).

Is pyrrhotite the same problem as pyrite under the slab?

No. The OACIQ’s page on the two minerals says pyrite is in the backfill around foundation drains or under the concrete slab, and that, once oxidized, the swelling can lift the slab or crack the foundation wall or the partitions. It says cases of pyrite swelling have been recorded in Montreal, in Rivière-des-Prairies and Pointe-aux-Trembles, and in Montérégie, from Notre-Dame-de-l’Île-Perrot to Sorel, and that other regions could also be affected. That geography is not the same sentence as the risk-zone page above. This page does not merge them.

The same page says pyrrhotite is a sulphide stone that, like pyrite, can swell when it oxidizes in contact with air and humidity, and that its oxidation can be much faster. It says the mineral is in aggregate from quarries in Mauricie and may have been added to the concrete used to pour foundations, that the chemical reaction makes the concrete burst and crack in a characteristic way, and that a petrographic analysis by a recognized laboratory is strongly recommended for buildings built between 1996 and 2008 in Mauricie (Pyrite ou pyrrhotite, page in French). The norms of Quebec’s program for homes damaged by pyrrhotite also name Centre-du-Québec, and residential buildings built in that period (Normes du programme, PDF). The program ended on 30 September 2026 (Programme pyrrhotite). It is not a program for pyrite in the backfill under a Montreal slab. No page cited here describes a current assistance program for that backfill. BNQ 2560-500 says its test method does not apply to the sulphate reactions that can degrade concrete (BNQ 2560-500/2022, scope, page in French).

Is a pyrite test required, and what are CTQ-M200, the BNQ and the IPPG?

Not as a condition of the deed, on any page cited here. On a brokerage sale in a risk zone, the OACIQ tells the broker to tell the selling client that an expertise should be done quickly, to determine whether pyrite causes or may cause problems. The same page says that, when an analysis is required in a transaction, licence holders should use recognized laboratories that apply methodology CTQ M-200. It says that methodology, though voluntary, is currently the only one recognized by the competent authorities. It lays down the measures for the visual survey of disorders affecting a property, and for sampling and analyzing the backfill. The page also says a broker or an agency must never advise a client to deal with an unrecognized laboratory, and that a building inspection alone is not enough to detect pyrite problems with certainty (High-risk areas for pyrite). “Should” and “when an analysis is required” are the OACIQ’s words to the broker. They are not an article of the Civil Code.

The petrographic swelling-potential index, the IPPG, is not a percentage and it is not a pass mark this page will invent. The OACIQ says a broker must not write, into a promise to purchase, a pyrite-test clause with a percentage as the threshold beyond which the buyer may withdraw. It says the organization has never issued a directive setting such a threshold, and it gives 10% as an example of a figure some brokers have written. It says the broker is not authorized to set that threshold, and that the threshold is not enough to assess the risk. It says the IPPG is a scale from 0 to 100, 0 meaning no potential and 100 an extremely high potential. Its footnote cites Protocole CTQ-M200, version 2.0, 4 June 2001, 47 pages, by the Comité technique québécois d’étude des problèmes de gonflement associés à la pyrite. As that footnote quotes the protocol, the index is determined by megascopic examination, and the swelling potential may have to be specified by optical microscopy or by chemical analysis. The same quotation says other factors have to be considered before a final judgment: sulphide content and type, chemical analyses, residual sulphides, the age of the building, the thickness of the backfill, and sulphate attack on the concrete. The OACIQ’s own example is that a threshold of 10 could let a buyer withdraw at an IPPG of 15 even if the report, after those other factors, concluded that no corrective work was required (Clause pyrite et pourcentage, page in French). This page states no cutoff.

Two BNQ standards are not the same job. BNQ 2560-500/2022, third edition of 8 November 2022, replaces the edition of 28 November 2003. It specifies the test method for the IPPG of granular materials and the chemical analyses to perform. Its scope is the sulphate swelling potential of granular materials used as backfill under non-structural concrete slabs inside buildings, residential, commercial or industrial, or for work on those buildings. It may be used for rock in place. It applies in an expertise on an existing building only if it is part of a complete expertise that includes a visual inspection by a professional, or under that professional’s supervision, taking all the data into account before an opinion. The BNQ’s notice says the document was prepared as a voluntary reference, and that the user checks whether a statute or a regulation makes its use mandatory (BNQ 2560-500/2022, summary, page in French). No page cited here is a statute that makes that test a condition of the deed.

BNQ 2560-510/2022 says how the results of that method are used for aggregates at the production site, the materials called DB. The preamble says CTQ-M100, finished in April 1999, and CTQ-M150, presented in May 2000, are now integrated into BNQ 2560-500 and BNQ 2560-510. It says an agreement between the ACRGTQ and the APCHQ identifies materials characterized under the standard, and used as backfill under the concrete slabs of residential, commercial and industrial buildings, as DB materials, with examples such as DB 0-20 mm and DB 10-14 mm. The same introduction says the standard does not aim to characterize samples taken during an expertise on an existing building, because protocol CTQ-M200 already covers that, and that the criteria in BNQ 2560-510 must never be used for those expertises (BNQ 2560-510/2022, summary, page in French).

What does the declaration ask, and what does the warranty still require?

On a brokerage sale, the OACIQ tells the broker that the mandatory form, when required in residential matters, is where you indicate whether or not you are aware of pyrite. Divided co-ownership has its own version of the form. On the PDF the other pages of this site read, D13.2 asks whether tests or expert reports have been done, beyond those already mentioned, and it names pyrite and pyrrhotite among them. It asks whether you can provide the documents and, if not, what the report found. D3.1 asks whether soil problems have affected the immovable. D15 is where the place, the year and how the situation was dealt with are written (Déclarations du vendeur sur l’immeuble, form DV). When that form is mandatory, and what a false answer does, is the declaration page already cited. The form does not order a new test for the sale.

Article 1726 says the seller warrants that, at the time of the sale, the property and its accessories are free of latent defects which render it unfit for the use for which it was intended, or which so diminish its usefulness that the buyer would not have bought it or paid so high a price if he had been aware of them. The seller is not bound to warrant a latent defect known to the buyer, or an apparent defect. An apparent defect is one a prudent and diligent buyer can perceive without an expert (Civil Code of Québec, article 1726). Article 1727 says that if the property perishes because of a latent defect that existed at the time of the sale, the loss is borne by the seller, who must restore the price. If the loss results from superior force, or from the buyer’s fault, the buyer deducts the value of the property in the condition it was in at the time of the loss (Civil Code of Québec, article 1727). Article 1728 says that if the seller was aware of the latent defect, or could not have been unaware of it, the seller is bound not only to restore the price, but also to make reparation for the injury the buyer suffered (Civil Code of Québec, article 1728).

Article 1729 is a presumption, and it is for a sale by a professional seller. A defect is presumed to have existed at the time of the sale if the property malfunctions or deteriorates prematurely in comparison with identical property, or property of the same type. The presumption is rebutted if the defect is due to improper use by the buyer (Civil Code of Québec, article 1729). Article 1730 binds the manufacturer, any person who distributes the property under their name or as their own, and any supplier, including an importer (Civil Code of Québec, article 1730). The article names those persons. It does not name the owner who sells their house. Article 1731 is a different sale. The French text in force says a sale under judicial control does not give rise to any warranty of the quality of the property sold. An ordinary sale by the owner is not that sale (Civil Code of Québec, article 1731).

A sale without the legal warranty does not remove the duty to disclose a known problem. Article 1732 says the parties may add to the warranty, diminish its effects or exclude it, but in no case may the seller exempt himself from liability for his personal acts or omissions (Civil Code of Québec, article 1732). Article 1733 says a seller may not exclude or limit liability unless the defects he was aware of, or could not have been unaware of, and which affect the right of ownership or the quality of the property, were disclosed. The same article makes an exception where a buyer buys at his own risk from a seller who is not a professional seller (Civil Code of Québec, article 1733). The exception is not a permission to stay silent. The OACIQ tells the seller’s broker that the waiver will not protect the seller against an action for defects of which he was aware and which he should have disclosed (The legal warranty of ownership and quality). Éducaloi says that, if the exclusion is real, the claim for a hidden defect is what is given up, and what remains is to show that the seller deliberately hid something so important that the buyer would not have bought, or would not have paid the same price (Immobilier : acheter sans garantie légale). How the clause is written is Selling a house as-is in Quebec. A notary or a lawyer reads the clause. This page does not.

What can a buyer or an inspector ask?

Only what the pages say. On a brokerage sale in a risk zone, the OACIQ says the broker informs every buyer about pyrite even if the property does not seem affected, informs the buyer of the seller’s declarations, and says that only an expertise can determine whether the property may be affected. If the expertise has been done, a copy goes to the buyer and to the building inspector. The buyer may consult their own expert to interpret it before a promise. If work was done, a copy of the invoices describing that work goes to the buyer and to the inspector. If the expertise has not been done, the OACIQ says the broker recommends that the buying client make the promise conditional on the analysis, generally at the seller’s expense, and on its results, allowing about three weeks, using the recommended form Annex – Expert report. The buyer, not the broker, decides whether the result is satisfactory. A buyer does not usually bear the cost of an expertise and cannot have it done without the owner’s authorization. The broker must not set a percentage threshold. No one may conceal information on the pretext that it might hinder the sale (High-risk areas for pyrite). Those sentences are what the OACIQ tells the broker. They are not a rule that every private sale includes a new test.

Éducaloi says the law does not require the buyer to hire an inspector, and that the buyer does have to be prudent about apparent defects. A pre-purchase inspection is a visual examination. It does not open walls, it does not guarantee that there is no latent defect, and a serious finding can be a reason to negotiate the price or to withdraw the offer. Éducaloi says these inspectors hold a residential building-inspector certificate from the Régie du bâtiment du Québec, and that category 1 covers houses and residential buildings of six dwellings or fewer (L’inspection préachat). That visual inspection is not the expertise the OACIQ describes. The OACIQ also says a broker must not give an opinion on the origin of a crack.

Which papers help if a test or earlier work was already done?

The useful ones, if you have them, are the laboratory report, the invoices that describe work a contractor already did, and anything the form’s D13.2 and D15 already ask you to attach. The OACIQ says a copy of the expert report, and the detailed invoice if work was done, goes to any buyer, whatever the result. The form does not order a new test.

If the fill was supplied as a DB material, BNQ 2560-510’s own summary lists, among its contents, weigh tickets and delivery slips, and an example attestation of DB materials. Those papers, if you have them, are papers in the file. The summary does not say a notary requires them before the deed. D2.4 asks for the new-home warranty documents if that warranty is still in force. The Régie, on the pyrite and pyrrhotite page already cited, says its role is to see that the administrators of the guarantee respect the Regulation respecting the guarantee plan for new residential buildings. It says that, if you are still covered, you check the protections and the claim procedure, and that the deadlines matter. It says the guarantee offered by the plan ends five years after the end of the construction work, and that after that delay the house is no longer covered by the plan. This page does not say whether one house is still inside those five years. None of the pages cited here says a notary requires a new pyrite test before the deed.

What are the ways to sell, including a direct sale as it stands?

Three paths are not the same promise. You can sell with the backfill still there, and say what you know. On a brokerage sale in a risk zone, that is the form, and it is the expertise the OACIQ tells the broker to recommend. The same page says that, if a problem is detected, it must be corrected or the selling price must take it into account, otherwise the property may be difficult to sell. That is what the OACIQ tells the broker to say. It states no percentage, so this page states none, and it does not tell you to do the work. On a sale with no broker, you still say what you know, in writing. Selling without the legal warranty is a clause in the promise and the deed. It does not cover a problem you knew and did not disclose. Mould, or water in the walls, is a different fact (Can you sell a house with mould in Quebec?). Asbestos or vermiculite is a different material (Can you sell a house with asbestos or vermiculite in Quebec?).

A direct sale is a third path. A buyer who takes the house as it stands, and whose offer has no inspection condition, is not a promise that waits on a laboratory test. The duty to say what you know is the same, and an offer with no inspection condition does not, by itself, set aside the legal warranty of quality. That depends on the warranty clause in the deed, which the notary reads.

Bruce Malcolm buys houses himself on the Island of Montreal and the surrounding areas. He holds no broker, agent or appraiser licence, and he is not an advisor. There is no inspection and no commission. An offer with no inspection condition does not, by itself, set aside the legal warranty of quality. You say what you know about the backfill when you send the address: any test you already have, and any work a contractor already did. He does not remove the backfill. The closing date is one you choose once the notary can sign. Sending the address starts a conversation (request an offer). The form does not commit you.