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Inspection of pyrite: knowing how to detect it before suffering the nightmare

More and more buyers are aware of the need to have pyrite inspected to ensure that it is not present in the desired building. The certified home inspector can best advise you on this, from detection to disposal advice.

Here is a bit of history to get to know pyrite better… The one we call madman’s gold. Let us first consider how the Régie du Bâtiment du Québec describes it: ” Pyrite is a mineral found in stone and which produces sulfuric acid by oxidizing on contact with humidity and oxygen. When this phenomenon occurs below a foundation, it can cause heaving and cracking of the concrete slab . “

Pyrite made its appearance in the 1980s, although it was found in certain constructions of the 1970s. However, it was only after ten years that the damage caused by pyrite became apparent or at least detectable. In Quebec, the discovery of pyrite following building inspections, made it possible to target regions where the presence of pyrite is more frequent. (see further down in this page).

Since 1999, builders have voluntarily applied the CTQ-M100 standard to exclude stone from embankments at risk of pyrite.

Pyrite inspection recommended by real estate agents

In an article in La Presse in 2014, a real estate broker explained that on the South Shore of Montreal, she systematically offered pyrite inspection to future property buyers. Clearly, this is the demonstration of how common the problem can be.

How pyrite acts on structures

In summary, the pyrite problem is explained by the use of a contaminated backfill under the concrete slabs of certain constructions. On contact with humidity, this backfill oxidizes and produces gypsum crystals which will expand, causing the slab to heave. Cracks then appear on the surface in the concrete of the slabs of garages or basements.
Expansion does not always happen vertically. When it comes to lateral expansion, it is possible that pyrite will damage the foundation of the building itself. This is why, even if you are a homeowner and do not intend to sell your home in the short term, it would be to your advantage to conduct a pyrite inspection before the damage is more costly to repair.
In order to assess the potential damage, the scale used is called the IPPG (petrographic index of swelling potential). This is to determine the possible expansion of pyrite:
-Between 0 and 20, the risk is zero to low
-Between 21 and 40, low to medium
-From 41 to 60, medium to high
-From 61 to 80, high
-From 81 to 100, extremely high
The newspaper L ‘ Écho de la Rive-Nord recently reported on the towns most affected by pyrite .

-South Shore of Montreal
-North Shore of Montreal
-Les Basses-Laurentides
-East and West ends of the city of Montreal

In the greater metropolitan area, 91 cities that were identified as having buildings with a pyrite problem . More recently, the Montérégie sector has shown many cases, particularly in the following municipalities:

-Saint-Bruno-de-Montarville
-Saint-Basile-le-Grand
-Sainte-Julie
-Beloeil
-Chambly
-Carignan
-Varennes
-Saint -Hubert
-Greenfield Park
-Sainte-Catherine

Pyrite tests carried out in the laboratory

Your home inspector is in the best position to inform you of signs of the presence of pyrite . He is also the one who can recommend the various additional tests that you should perform to establish the situation. Beyond the signs that suggest the presence of pyrite , laboratory tests can more precisely indicate the state to which the building is facing (IPPG).

By choosing to proceed with a home inspector, you also ensure that you can have a more complete picture of the impact of the presence of pyrite on the entire property or building.

Purchase of property and presence of pyrite

has an interesting section on its website to let you know what to do, at each step of the process of buying a home that is found to be contaminated with pyrite. Also, in the case of a sale, we mention in particular:
  • that you have a duty to educate any buyer about pyrite, even if the property does not appear to be affected;
  • that he must, when required in residential matters, complete the mandatory  Declarations by the seller of the immovable form  , indicating whether or not he is aware of the presence of pyrite;
  • that an expert assessment should be carried out quickly to determine whether pyrite is causing or could cause problems;
  • that a buyer usually does not assume the cost of an expertise and that he cannot do so without the authorization of the owner;
  • that if a problem is found, it must be corrected, or the sale price must reflect that problem. Otherwise, the building could be difficult to sell;
  • that a copy of the expert’s report (and, if applicable, the detailed invoice for the repairs carried out) must be sent to any buyer, regardless of the result of the analysis.
Do not hesitate to call on a certified building inspector to ensure compliance with the standards of practice in building inspection.