ImmoMulti — direct buyer of income properties on the North Shore — regularly meets sellers worried about a crack in their plex's foundation. Good news: the vast majority of cracks found in Québec residential foundations are shrinkage cracks, with no structural consequence. For a seller, the real issue is not the crack itself, but correctly classifying it (shrinkage or structural), disclosing it honestly to avoid a hidden-defect claim, and controlling its impact on price and the buyer's financing. This guide explains how to approach selling a duplex, triplex or quadruplex with foundation cracks — on the North Shore and across Québec.
Shrinkage crack or structural crack: how to tell them apart on a plex?
A shrinkage crack is thin, vertical, stable and harmless: it results from concrete drying. A structural crack (wide, horizontal, stair-stepped or progressive) comes from mechanical forces — soil movement, hydrostatic pressure, overload, freeze-thaw. Only a qualified professional can confirm the nature of a crack.
The first question to ask when facing a crack is not "is it serious?" but "what type is it?". In Québec, the vast majority of cracks observed in residential foundations are shrinkage cracks: they appear as new concrete cures and dries, are generally thin, vertical and stable over time. They may let a little moisture through, but they do not threaten the building's soundness.
Conversely, a structural crack results from mechanical forces on the foundation: soil movement, hydrostatic pressure, overload, or repeated freeze-thaw cycles against a poorly drained wall. These cracks are often wider and may be horizontal, stair-stepped (following the block joints) or progressive — meaning they widen over time.
| Clue | Shrinkage crack (benign) | Structural crack (watch) |
|---|---|---|
| Width | Thin (hairline to 2–3 mm) | Often wide, open |
| Orientation | Vertical | Horizontal, stair-stepped, diagonal |
| Evolution | Stable | Widens over time |
| Associated signs | None / slight moisture | Bulging wall, sagging floor, sticking doors |
| Seller action | Injection possible, disclose | Engineer's report recommended |
Technical nature of cracks verified with Québec building-inspection and foundation-expert firms. Where a crack is in doubt, only a qualified professional (technologist, building inspector or engineer) can provide a reliable diagnosis.
What are the common causes of foundation cracks in Québec?
Understanding the cause helps the seller answer the buyer's questions and pick the right strategy. Québec foundations face a harsh climate, variable soils and marked freeze-thaw cycles. Here are the most common causes:
- Shrinkage of new concrete: the most frequent and most benign cause — concrete contracts as it dries.
- Clay soils: clay swells with moisture and contracts during drought. These movements cause differential settlement and cracking. A plex built on clay deserves particular attention.
- Freeze-thaw cycles: water that freezes against a poorly drained wall exerts repeated pressure on the foundation.
- Defective French drain: a clogged or collapsed drain lets water accumulate around the foundation. This is a frequent cause of infiltration in Québec buildings aged 20 to 35 years, with clay accelerating the clogging.
- Pyrite-related swelling: more rarely, pyrite-contaminated backfill under the slab can swell on contact with water and air, cracking the concrete slab of the basement or garage.
What the buyer will want to know
- Is the crack stable or progressive?
- Is the soil clay? Has there been any past infiltration?
- Has the French drain been inspected or replaced, and when?
- Has a pyrite test ever been done on the backfill?
Technical sources: Québec building-inspection and foundation-expert firms; the Association des consommateurs pour la qualité dans la construction (ACQC) on pyrite and backfill swelling.
When should a crack be assessed by an engineer before selling?
Consult a building structure engineer if the crack is wide, horizontal, stair-stepped, progressive, or paired with a bulging wall, a sagging floor, sticking doors or infiltration. An engineer's analysis is especially recommended if the plex sits on clay or unstable soil.
Not every crack warrants an engineer's report. For a typical shrinkage crack, the opinion of a building inspector or technologist is often enough. But certain signals call for the expertise of an engineer who is a member of the Ordre des ingénieurs du Québec, whose field of competence covers building structure, framing and foundations:
- a horizontal or stair-stepped crack;
- a crack that widens from one visit to the next;
- bulging or tilting of the foundation wall;
- a sagging floor, doors or windows that stick;
- recurring water infiltration in the basement;
- a plex built on clay or backfill soil.
A report signed by an engineer gives an objective read of the situation — nature of the problem, probable cause, recommended fixes — and turns an anxiety-inducing unknown into a controlled data point for negotiation. For the seller, it is also a piece that demonstrates good faith: you had it checked, you disclose, you concealed nothing.
Source: Ordre des ingénieurs du Québec — competency profile "Building structure, framing and foundations".
Disclosure obligation: foundation cracks and hidden defects
The legal warranty of the Civil Code requires the seller to warrant the buyer against hidden defects: a serious flaw, not apparent, existing at the sale, that the buyer could not have detected through a careful examination. Concealing a known foundation problem exposes you to a claim, even in a sale "without legal warranty".
This is the heart of the matter for the seller. In Québec, the legal warranty applies automatically to the sale of a building: the seller must warrant the buyer against hidden defects. According to Éducaloi, a hidden defect is a flaw serious enough to reduce the building's use, not apparent at the time of sale, existing before the sale, and that the buyer could not detect through a careful examination by a prudent person.
In practice, if you know of a foundation problem — a structural crack, repeated infiltration, a past repair — you must disclose it. The seller's declaration must be complete and honest. A seller who deliberately hides a known defect risks a lawsuit for a price reduction or cancellation of the sale, with damages.
"The seller is bound to warrant the buyer that the property and its accessories are, at the time of the sale, 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 would not have paid so high a price, had he been aware of them."
— Principle of the seller's legal warranty, as explained by Éducaloi (Civil Code of Québec)A sale can be made "without legal warranty, at the buyer's own risk" if the promise to purchase and the deed provide for it. But be careful: according to Éducaloi, this exclusion does not protect a seller who knew about the defect and concealed it. A seller in bad faith remains liable. The clause reduces your exposure; it never replaces honest disclosure. Have it drafted and framed by your notary.
The trap to avoid
Repainting a foundation wall to mask a crack or an infiltration stain just before showings can be interpreted as concealment. This is exactly the kind of act that flips a "without legal warranty" sale into liability for a hidden defect. Disclose instead, with documents to back it up.
Sources: Éducaloi — "The hidden defect in a building" and Éducaloi — "The legal warranty". For your specific situation, consult a notary or lawyer.
Impact of a crack on the price and financing of your plex
Financially, everything again hinges on the nature of the crack. A minor shrinkage crack has little or no effect on the price of an income property. An active or structural crack, on the other hand, often leads to a downward negotiation.
The buyer reasons like this: they estimate the repair cost, then add a safety margin for uncertainty. That is why a documented crack (engineer's report + repair quote) usually costs you less than an unexplained crack: the uncertainty, which buyers always overestimate out of caution, is removed.
On the financing side, a structural problem can complicate the buyer's loan. A lender or mortgage insurer may require an engineer's report, hold back part of the funds until the work is done, or refuse to finance a building with an uncorrected structural defect. For a plex — where the loan is often conditional on the building's condition — a clear file speeds up approval and prevents a transaction from failing at signing.
Estimate the cost of foundation workPrice a repair before you set your asking price →Repair the foundation before selling the plex, or sell as-is?
There is no single answer: the right choice depends on the scope of the problem and your horizon.
- Shrinkage crack: an epoxy or polyurethane injection is inexpensive, fast, and reassures the buyer. It is often worth doing before listing.
- Defective French drain: replacement (excavation) is a heavy job. Depending on the drain's condition and the expected price, it may be worth doing — or disclosing and adjusting the price.
- Major structural repair (piling, wall straightening): costly, and it does not always pay off in the sale price. Many sellers then prefer to sell "as-is".
- Pyrite problem: the definitive fix means removing the slab and the contaminated backfill. This is a typical case where an "as-is" sale to an informed buyer is often the simplest path.
Selling "as-is" to a specialized buyer avoids tying up capital and time in foundation work before selling. ImmoMulti buys North Shore income properties as-is — duplex, triplex, quadruplex — even with foundation work to plan for, with no broker and no commission. You disclose the real condition, we factor it into the offer, and you recover your capital without managing the work.
