Most foundation cracks in Calgary homes are normal and meaningless. A few are not, and the difference is usually visible.
Thin vertical cracks in a poured concrete foundation. Concrete shrinks as it cures and continues to move seasonally. Narrow vertical cracks — particularly in the middle of a wall span, and particularly where the two sides are level with each other — are extremely common and rarely structural.
They can still let water in, which is a different problem with a straightforward fix. Wet is not the same as unstable.
Supporting signs elsewhere in the house matter too: doors that will not latch, windows that stick, sloping floors, and new drywall cracks radiating from door corners. One of those alone means little. Several together, plus a foundation crack, is a pattern.
A home inspector will flag it. Only a structural engineer can tell you what it means and what it costs — and that report is worth ordering during the condition period rather than guessing.
Permanent wood foundations — built from pressure-treated lumber rather than concrete — do exist here, more often in rural and acreage properties and in certain build eras. They are an engineered, code-recognised system, not a defect.
Practical considerations: they depend heavily on drainage being correct and staying correct; some lenders and insurers treat them differently; and the buyer pool at resale is narrower simply because they are unfamiliar. None of that makes one a bad purchase — it makes it something to price accurately and to have inspected by someone who has seen them before.
Do not walk on a crack alone, and do not wave one away either. Get it identified, get a cost if it needs one, and negotiate on the number. Foundation issues are among the few findings where the range between "nothing" and "very expensive" is wide enough that guessing is genuinely reckless.