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.
Field diagnosis: reading a foundation crack before listing your plex
Before calling a professional, a seller can already document a crack: measure its width, note its orientation, place plaster tell-tales to check whether it moves, and photograph its evolution. These observations guide the decision on whether to bring in an engineer.
Many sellers panic at the sight of a crack without ever really observing it. Yet, before spending on an expert assessment, you can gather reliable clues. The goal is not to diagnose the crack yourself — that is a qualified professional's job — but to build an observation file that will save you time and money, and that will demonstrate your good faith on disclosure day.
Measuring the width: the 3 mm rule
A crack's width is the first clue to its severity. A hairline crack (thinner than 1 mm) is almost always a benign shrinkage crack. Between 1 and 3 mm, you are generally still in shrinkage territory, especially if the crack is vertical and stable. Beyond 3 mm, or if the crack widens at one end, caution calls for closer observation. Use a crack monitor (a transparent graduated ruler sold at hardware stores for a few dollars) or, failing that, a simple ruler and a magnifier. Note the width at the widest and narrowest points.
Placing tell-tales to detect movement
A stable crack is not the same as an active one. To settle the question, the classic method is the "tell-tale": you apply a small plaster patch across the crack, or glue a strip of paper, or draw two dated pencil marks on either side. If, a few weeks or months later, the plaster cracks, the paper tears or the gap between the marks grows, the crack is active — it is still moving. This is one of the most useful clues to tell a shrinkage crack (stable) from a structural crack (progressive), and it is data any engineer will appreciate.
| Observation to document | What it indicates | Tool |
|---|---|---|
| Width (mm) | <1 mm hairline, 1–3 mm watch, >3 mm assess | Crack monitor / ruler |
| Orientation | Vertical = often shrinkage; horizontal/stair = possible structural | Level, photo |
| Movement over time | Stable = reassuring; opens = active | Plaster tell-tale, dated marks |
| Moisture / efflorescence | White traces = recurring water passage | Visual inspection |
| Related signs | Sticking door, sloping floor = structural movement | Rolling marble, level |
The marble test and the spirit level
A floor that has settled often betrays foundation movement. The simplest test: place a marble or an orange in the middle of a ground-floor or basement room and watch whether it consistently rolls the same way. Complete this with a spirit level on door thresholds and window sills. Sticking doors, offset frames or diagonal cracks above openings are signals that, combined with a foundation crack, point to a structural issue rather than simple shrinkage.
Your minimum observation file
- Dated photos of each crack, with a ruler or coin for scale
- Width measured at both ends
- Plaster tell-tales in place for at least a few weeks
- Notes on past infiltration (date, amount of water, repairs)
- Known history: building age, soil type, prior work
Common observation methods used in pre-purchase inspection; they do not replace a qualified professional's diagnosis. When in doubt, retain a building inspector or an engineer.
How much does foundation crack repair cost in Québec?
In Québec, injecting a crack from the inside (polyurethane or epoxy) generally costs CA$400 to CA$1,500 per crack. Exterior work with excavation and membrane climbs to CA$3,000–CA$5,000 per crack, and a major overhaul (drain, piling) runs into the tens of thousands.
For a seller, knowing the order of magnitude of costs changes everything: it lets you decide between repairing before the sale, adjusting your price, or selling as-is. Here are the ranges observed on the Québec market, as an indication — a contractor's quote remains essential for your specific case.
Interior injection: the most frequent solution
For a shrinkage crack or a fine crack that lets a little water through, injection is the most common repair. A resin is injected under pressure to fill the crack through its full thickness. Two materials dominate:
- Polyurethane: flexible, it tolerates slight movement and blocks water. Ideal for weeping cracks. Typical cost around CA$400 to CA$900 per crack, depending on length and access.
- Epoxy: rigid and very strong, it structurally "re-bonds" the concrete. Used when you want to restore mechanical strength. Cost generally CA$300 to CA$1,000, sometimes more for a demanding structural crack.
In practice, an interior injection in Québec most often falls in a range of CA$500 to CA$1,500 per crack. That is a modest amount relative to the price of a plex, which is why many sellers prefer to settle a shrinkage crack before listing: the reassurance-to-cost ratio is excellent.
| Type of work | Target situation | Indicative range (per crack) |
|---|---|---|
| Polyurethane injection (interior) | Fine crack, weeping | ≈ CA$400 – CA$900 |
| Epoxy injection (interior) | Crack to re-bond structurally | ≈ CA$300 – CA$1,000 |
| Exterior repair + membrane (excavation) | Stubborn crack, persistent infiltration | ≈ CA$3,000 – CA$5,000 |
| French drain replacement | Clogged/collapsed drain | Several thousand to tens of thousands CA$ |
| Structural overhaul (piling, straightening) | Major foundation movement | Tens of thousands CA$ |
Indicative ranges compiled from specialized Québec foundation-repair sources (2024–2026), including Soumission Rénovation — price of a crack repair. Prices vary by length, access, urgency and region. Always request a written quote.
Worked example: triplex with two cracks
Take a North Shore triplex whose inspection reveals two weeping shrinkage cracks in the basement. The contractor proposes a polyurethane injection at CA$650 each, i.e. CA$1,300. The seller has two options: settle the CA$1,300 before listing and present the invoices, or disclose and let the buyer negotiate. As we will see, an unreassured buyer tends to overestimate the risk: they might demand a CA$5,000 discount "for the foundation" when the real cost is CA$1,300. Settling a small repair in advance often avoids a disproportionate discount.
Beware of "blind" quotes
Be wary of a contractor who prices a major repair without having seen the crack or the soil conditions. For a structural crack, the logical order is: diagnosis (engineer) → recommendation → quote. Paying for a heavy overhaul without a diagnosis risks treating the symptom without correcting the cause (a failing drain, for example).
The seller's declaration: how to disclose a crack without hurting yourself
In Québec, the Declarations by the Seller of the Immovable form (DV) is mandatory whenever a broker sells, for a private individual, a residential building of fewer than five dwellings. It must disclose, among other things, water damage, the presence of pyrite and known problems — including foundation cracks and infiltration.
Disclosure is not just an abstract principle: in Québec it often runs through a specific document, the Declarations by the Seller of the Immovable (OACIQ's DV form), mandatory since July 2012 when a broker represents the seller of a primarily residential building of fewer than five dwellings (so duplex, triplex and quadruplex). For a divided co-ownership, it is the DVD form. This form asks the seller to declare, among other things, water damage, the known presence of pyrite, radon or asbestos, work carried out, and any problems they are aware of.
What to write about a crack
When you know of a crack or infiltration, the rule is simple: write what you know, as you know it. Do not invent a diagnosis you do not have, but do not downplay it either. An honest wording looks like this: "Vertical crack on the north foundation wall, basement, observed since 2021, stable, polyurethane injection in 2022 (invoice attached). No infiltration since." This precision protects the seller: you disclosed, documented and dated.
- Locate the crack (wall, orientation, floor).
- Date its first observation and its evolution.
- Describe any infiltration and its frequency.
- Attach repair invoices, engineer's reports and quotes.
- Do not assert there is "no problem" if you are not certain.
Selling without a broker: disclosure is still owed
Selling privately, with no broker? The OACIQ's DV form is then not legally required, but the duty to inform and the warranty against hidden defects still apply. Nothing stops you — and everything encourages you — to voluntarily fill out an equivalent written declaration. It is a protection for you: in a dispute, a dated and signed document where you disclosed everything demonstrates your good faith far better than a conversation nobody remembers the same way.
"The Declarations by the Seller form lets the seller pass on to the potential buyer the information they know about the property, fostering a transparent transaction."
— Based on the Organisme d'autoréglementation du courtage immobilier du Québec (OACIQ)Sources: OACIQ — the Declarations by the Seller form. The mandatory nature applies to broker-assisted transactions; the duty to disclose and the legal warranty remain in private sales. Consult a notary for your situation.
Hidden defect: timelines, notice and seller liability
A buyer who discovers a hidden defect must notify the seller in writing within a reasonable delay — often assessed at between six months and one year depending on circumstances. The starting point of the prescription period is the moment the defect, or its severity, is discovered.
Many sellers believe that once the deed is signed, they are in the clear. That is not accurate. The legal warranty survives the sale, and a buyer may turn against you later if they discover a hidden defect. Understanding the timelines and the mechanics of a claim helps you gauge your real exposure — and understand why careful disclosure is your best insurance.
Written notice within a reasonable delay
According to Éducaloi, a buyer who finds a hidden defect must notify the seller in writing, within a reasonable delay after discovery. This delay is assessed case by case: the time needed to identify and measure the severity of the problem is taken into account. In practice, a delay of about six months to one year is often considered reasonable, and it can exceptionally be longer when the defect appears seasonally — which is common for infiltration linked to freeze-thaw or the spring melt. If the buyer does not send this notice, or sends it too late, they risk losing the right to compensation.
The starting point of the prescription
For a hidden defect, the prescription (the countdown to sue) begins at the moment the defect is discovered — not on the date of sale. If the flaw appears gradually, it is the moment the buyer can suspect the severity of the problem that counts. Concretely, a crack that turns into infiltration two winters after the sale can still give rise to a claim. Hence the importance, on the seller's side, of keeping a record of everything you disclosed: this file is your defence.
| Step (buyer's claim) | What happens | Seller's stake |
|---|---|---|
| Discovery of the defect | Prescription period begins | Prior disclosure can defeat the "hidden" character |
| Written notice | Notice to the seller within a reasonable delay | A chance to discuss before litigation |
| Formal demand | Formal request for correction or compensation | Respond quickly, with documents |
| Claim | Price reduction, cancellation, damages | The seller in bad faith is most exposed |
Good faith vs bad faith: the dividing line
The distinction with the heaviest consequences is between the seller in good faith (who did not know of the defect) and the seller in bad faith (who knew and concealed it). The former can, in some cases, limit their exposure, notably with a warranty-exclusion clause. The latter remains liable despite a "without legal warranty" sale, and may also be ordered to pay damages. In other words: the seller's best protection is neither silence nor a magic clause — it is documented transparency.
Sources: Éducaloi — "Steps to follow in the case of a hidden defect" and Éducaloi — "Prescription". This is not legal advice; consult a lawyer or notary.
Negotiating the sale of a plex with a crack: frame it, don't absorb it
A crack documented with a report and a quote usually costs the seller less than a "bare" crack: it removes the uncertainty buyers always overestimate. The winning strategy is to price the repair yourself before the buyer improvises an inflated discount.
Negotiating around a crack follows a simple psychological logic: buyers hate the unknown. Faced with an unexplained crack, a buyer imagines the worst-case scenario and builds their offer accordingly — often with a discount out of all proportion to the real cost. The savvy seller's job is therefore to replace uncertainty with numbers.
The "uncertainty premium" mechanism
Picture two sellers with the same crack. The first tells the buyer: "There's a crack, deal with it." The cautious buyer subtracts CA$8,000 "just in case." The second presents an inspector's report confirming a shrinkage crack and an injection quote at CA$700. The buyer subtracts… CA$700, maybe CA$1,000 for margin. The CA$7,000 difference is not in the concrete: it is in the information. Documenting means converting a fear into a budget line.
Three possible negotiation stances
- Repair before the sale: you settle it, present the invoices, and the crack leaves the equation. Optimal for small repairs (injection).
- Credit at closing: you let the buyer arrange the work and grant a credit equal to the quote. Transparent and clean at the notary.
- "As-is" sale at an adjusted price: for heavy overhauls (drain, piling) that do not pay off, you sell to an informed buyer who purchases with full knowledge.
| Scenario | Estimated real cost | Likely discount if undocumented | Best stance |
|---|---|---|---|
| Shrinkage crack, dry | CA$0 – CA$700 | CA$2,000 – CA$5,000 | Report + injection before sale |
| Weeping crack | ≈ CA$700 – CA$1,500 | CA$5,000 – CA$10,000 | Repair or credit at closing |
| Drain to replace | Several thousand CA$ | Frequent over-discount | Quote + as-is to informed buyer |
| Structural overhaul | Tens of thousands CA$ | Offers that collapse | Engineer's report + as-is sale |
The "likely" discounts above illustrate the uncertainty premium: they are teaching orders of magnitude, not guaranteed market values. The message is the same: the stronger your file, the tighter the gap between real cost and demanded discount.
Special case of a tenant-occupied plex
A plex sells occupied. Inspector and engineer visits must therefore respect the rules for accessing a tenant's dwelling — notice, reasonable hours. Plan for time: coordinating access to several dwellings for a foundation inspection often takes longer than a single-family home. That is one more reason to prepare the file early, before you even receive an offer, rather than under the pressure of a ten-day inspection condition.
Five common seller mistakes when facing a foundation crack
Having seen many plexes with foundation issues, the same missteps keep coming up. Avoiding them saves you time, money, and sometimes a lawsuit.
Mistake 1 — Concealing instead of disclosing
Repainting the wall, placing a panel in front of the crack, patching it hastily before showings: these acts, even without malicious intent, can be seen as concealment. This is exactly what flips a "without legal warranty" sale into liability for a hidden defect. Disclose, with documents to back it up.
Mistake 2 — Panicking and dumping the price
At the opposite extreme, some sellers, terrified by the idea of a "foundation problem," accept the first low offer. Yet most cracks are benign. Classifying the crack before setting the price avoids leaving thousands of dollars on the table out of fear of a problem that may not exist.
Mistake 3 — Confusing inspector and engineer
A building inspector makes a visual observation; a structure engineer makes a diagnosis and signs a report engaging their professional liability. For a shrinkage crack, the inspector is enough. For a horizontal, progressive crack or one with a bulging wall, you need an engineer who is a member of the Ordre. Retaining the wrong professional means paying for a document that will reassure neither the buyer nor their lender.
Mistake 4 — Repairing without diagnosing the cause
Injecting a crack when the real cause is a clogged French drain means treating the symptom. The water will come back, the crack too, and you will have spent without fixing the root. The correct sequence: understand the cause (drain, soil, freeze-thaw), then choose the fix.
Mistake 5 — Waiting for the offer to handle the file
Discovering the crack during the buyer's inspection condition means negotiating from weakness, under time pressure. Preparing the file before listing — observation, report if needed, quote — puts you in control of the conversation.
The calm seller's checklist
- Cracks observed, measured, photographed and dated
- Nature classified (inspector or engineer as appropriate)
- Probable cause identified (drain, soil, shrinkage)
- Repair quote in hand
- Written disclosure ready, invoices attached
- Decision made: repair, credit, or sell as-is
Plex foundations on the North Shore: regional context and building types
On Montréal's North Shore, the age of plexes, the frequent presence of clay soils and marked freeze-thaw cycles make French-drain and settlement issues especially common. Knowing your area's profile helps you anticipate the buyer's questions.
The crack question is not experienced the same way depending on your building's age and type. A 1970s quadruplex on clay in Sainte-Thérèse raises different questions than a recent duplex on bedrock. Understanding the regional context lets you answer buyers with confidence.
Building age and the French drain's life cycle
The useful life of a residential French drain is generally estimated at 25 to 40 years, with an average around 30 years for most Québec buildings. Old drains in clay tile or concrete, laid before the 1980s, can begin to clog after 20 to 25 years. This matches the observation above: on plexes aged 20 to 35 years, a failing drain becomes a frequent cause of basement infiltration, often behind weeping cracks. If your plex is in that age bracket, the buyer will want to know whether the drain has been camera-inspected or replaced.
| Plex age | Typical foundation issue | Buyer's likely question |
|---|---|---|
| 0–15 years | Concrete shrinkage cracks | Are the cracks stable? |
| 20–35 years | End-of-life French drain, infiltration | Has the drain been inspected/replaced? |
| 35 years and over | Settlement, drain to redo, sometimes pyrite | Is there a history of movement? |
Indicative French-drain lifespans, compiled from specialized Québec residential-drainage sources (2026). Actual condition depends on materials, soil and maintenance; a camera inspection gives the true picture.
Clay soils and freeze-thaw: the duo that works foundations
A good part of the St. Lawrence lowlands, including several North Shore areas, sits on clay soils. Clay swells when it absorbs water and shrinks in dry spells: this back-and-forth imposes differential movement on the foundation that, over time, cracks the concrete. Add harsh winters and repeated freeze-thaw cycles against a poorly drained wall, and you get the classic conditions of Québec cracks. This is not a flaw of your building in particular: it is the lot of a large share of the regional building stock. Framing it that way for the buyer normalizes the situation.
Answering well by plex type
- Recent duplex: stress stability and the absence of any infiltration history.
- 1980s–90s triplex: have the drain's inspection or replacement date ready.
- Older quadruplex: prepare the full history (work, settlement, soil tests).
Whatever the type, the seller's logic stays the same: classify, document, disclose, then decide. A well-prepared plex sells, crack or not — it is the unknown, never the concrete, that scares buyers away.
A step-by-step action plan for the seller
To close, here is a simple sequence a plex seller can follow from the moment a crack is noticed to the moment the deal signs. It ties together everything above into one repeatable path.
- Observe and document. Measure width, note orientation, place tell-tales, take dated photos. Build the observation file.
- Classify. For a thin, stable, vertical crack, a building inspector's opinion is usually enough. For horizontal, stair-stepped, progressive cracks or those with a bulging wall, retain an engineer from the Ordre des ingénieurs du Québec.
- Find the cause. Is it shrinkage, a clay soil, freeze-thaw, or a failing French drain? A camera inspection of the drain often answers this on a 20-to-35-year-old plex.
- Get a quote. Interior injection typically runs CA$400–CA$1,500 per crack; exterior work with excavation CA$3,000–CA$5,000; a drain or structural overhaul far more.
- Decide your stance. Repair before listing, offer a credit at closing, or sell as-is at an adjusted price — matched to the scope and your horizon.
- Disclose in writing. Complete a seller's declaration (or the OACIQ DV form with a broker), attach reports, quotes and invoices. Transparency is your best defence against a later hidden-defect claim.
The one idea to remember
- Most cracks are benign shrinkage cracks.
- The unknown, not the crack, drives buyers away.
- Documented transparency protects your price and your peace of mind.
And if you would rather skip the foundation work entirely, selling as-is to a specialized buyer remains a clean exit: you disclose the real condition, it is factored into the offer, and you recover your capital without managing a jobsite.
