Six red flags and where they are reported in Quebec

Six problems come up again and again in Quebec: iron ochre, pyrite, vermiculite, an oil tank, a flood zone, and radon. None of them shows up in photos. Each one is settled by a specific test, before your inspection condition expires. Here is what each one is, where it is commonly reported, and what to ask.

One methodological note first: a region is not a diagnosis. What follows says where a problem is commonly reported, not where it is. Two neighbouring houses can give opposite results. Only the test decides.

Iron ochre (ocre ferreux)

Iron-rich groundwater meets oxygen inside the French drain (drain français); bacteria turn the iron into an orange, gelatinous deposit that clogs the drain. Water stops draining and comes back up into the basement.

Commonly reported where the water table is high and soils are iron-rich: many municipalities on the South Shore, in the Montérégie, Lanaudière, the Laurentians and the Mauricie.

Signs: orange deposit in the sump pit, a ferrous smell, a pump that runs often, a drain replaced early in the life of the house.

How to verify: a camera inspection of the French drain, examination of the sump, and a laboratory analysis of the groundwater. Replacing an affected drain is an excavation job, not a repair.

Pyrite

Pyrite in some crushed stone used as backfill under the concrete slab oxidizes, swells and lifts the slab. It reads as star-shaped cracks in the basement floor and partitions that bind.

Commonly reported in the greater Montreal area, especially on the South Shore and in the northern suburbs, for houses from the 1970s to the 1990s, before backfill requirements tightened. Age alone proves nothing.

Signs: cracks radiating from one point in the floor, a domed slab, basement doors that rub, partitions cracked where they meet the ceiling.

How to verify: a petrographic laboratory analysis of the backfill, from a core taken under the slab. The report concludes on the swelling potential of the material. That document is the only one that counts; a visual opinion is not enough.

Vermiculite and asbestos

Vermiculite is a beige-gold granular insulation, often poured into attics and sometimes into wall cavities. Part of the vermiculite sold in North America until the early 1990s came from a mine whose ore contained asbestos.

Commonly reported across Quebec in houses built before the 1990s, with no regional pattern.

Signs: light, shiny, accordion-like granules in the attic. Do not disturb them and do not vacuum.

How to verify: sampling by a specialized firm and a laboratory analysis. Intact and undisturbed, vermiculite is generally left in place; the cost appears when work — insulating, rewiring, extending — disturbs it. Ask what your renovation plan implies before you buy.

Oil tank (réservoir de mazout)

An oil tank, in the basement or buried in the yard, can leak and contaminate the soil. Decontamination and excavation are among the heaviest bills a buyer can inherit, and the liability follows the land.

Commonly reported in houses heated with oil before conversion to electricity, everywhere in Quebec, the island of Montreal included.

Signs: a fill pipe or vent on the façade, a concrete circle in the yard, a tank cradle in the basement, an oily smell, a mention of former oil heating in the seller's declaration (déclaration du vendeur, DV).

How to verify: ask for written proof that the tank was removed and, if it was buried, a soil characterization by a specialized firm. Talk to your insurer as well: a tank changes underwriting.

Flood zone

Flood zones are classified by recurrence: the high-velocity zone (0–20 years) and the low-velocity zone (20–100 years). The classification governs what you may build, rebuild and sometimes insure.

Commonly reported along the waterways of the metropolitan area — rivière des Prairies, rivière des Mille Îles, lac des Deux Montagnes, Richelieu river — and in the riverside sectors hit by the 2017 and 2019 floods.

Signs: proximity to water, a basement converted without a permit, a claims history, recently added fill on the lot.

How to verify: the municipality's zoning map and the by-law that applies to it, the urban planning department's file, and written confirmation from your insurer and your lender before you make an offer. The rules keep changing: rely on the map in force on the day you buy, not on a memory.

Radon

Radon is a natural radioactive gas that seeps in through foundation cracks and builds up in closed spaces at the bottom of the house. It has no smell and no colour. Health Canada recommends acting when the annual average concentration exceeds 200 becquerels per cubic metre.

Commonly reported everywhere in Quebec, the Montreal area included. The house — its foundation and its ventilation — decides, not the postal code.

How to verify: a long-term test, over at least three months in the heating season, is the only reliable measurement. A quick test during an inspection condition is an indication, not a conclusion. Mitigation goes through a sub-slab depressurization system.

What verification costs

We do not publish prices we have not verified, and these tests are quoted file by file. What we can say: the Home Judge evaluator budgets $600 by default for the pre-purchase inspection itself, and each of the tests above is billed on top, by a specialized firm. Ask for three written quotes with turnaround times: it is the delay, not the price, that makes an inspection condition fail.

FAQ

Does a pre-purchase inspection cover iron ochre and pyrite?

Rarely. A general inspection notes visible signs and recommends expert reports. The drain camera and the backfill analysis are separate mandates, to be requested and paid for separately.

Can I run these tests after buying?

You can, but you lose your leverage. These checks exist to decide whether to buy, to renegotiate, or to walk away during the inspection condition.

Does vermiculite force a remediation?

Not in itself. Intact and undisturbed, it is generally left in place. The cost appears when work disturbs it: plan for it in your renovation budget.

Is a house in a flood zone insurable?

It depends on the classification, the building and the insurer. Get written confirmation from your insurer and your lender before submitting a promise to purchase, not after.

Does the seller have to tell me about these problems?

The seller must disclose what they know, and the seller's declaration (DV) is where that happens. A sale "without legal warranty, at the buyer's own risk" does not excuse the seller's personal acts, but it does leave the rest with you.