Foundation problems
Vertical Foundation Cracks
There is a vertical crack in my foundation. Is it serious?
Usually not. Vertical and near-vertical cracks are most often shrinkage cracks left over from the concrete curing in the first year of the foundation's life, and a large proportion of Calgary basements have one. Four things change that assessment: width beyond about 6mm, the two faces no longer sitting flush, visible growth over time, and water coming through. Absent all four, a vertical crack is usually a maintenance item rather than a problem.
We are a referral service, not a contractor. Your request goes to an independent Calgary foundation company.
Most examples of this need monitoring rather than repair.
What you are probably seeing
- A crack running roughly straight up and down, often narrower at one end
- Frequently starting at the corner of a basement window or at a service penetration
- Typically hairline to a few millimetres wide
- Sometimes damp or showing white chalky deposits during spring melt
- Often present for years without any change
What causes it
- Concrete shrinkage
- Concrete loses volume as it cures over roughly the first year and relieves that stress by cracking. This is the most common cause by a wide margin, and it indicates nothing about the strength of the wall.
- Stress concentration at openings
- Corners of windows and service penetrations concentrate stress, which is why shrinkage cracks so often start there rather than in the middle of a blank wall.
- Minor uniform settlement
- Slight, even settlement in a foundation's early years can produce vertical cracking without indicating a structural problem, because the whole foundation is moving together.
- Freeze-thaw widening an existing crack
- Calgary's repeated winter crossings of zero do not usually create the first crack, but water sitting in an existing one freezes, expands and levers it wider over successive seasons.
- Differential settlement, when the crack is diagonal
- A crack that leans noticeably rather than running straight up, particularly one widening toward the top, is a different mechanism and belongs with settlement rather than shrinkage.
How serious is yours?
The left column is worth acting on. The right column is genuinely fine to watch, and saying so is the point of this page.
Get this assessed
- Get this looked at: Wider than roughly 6mm, about the width of a pencil
- Get this looked at: The two faces are no longer flush when you run a finger across
- Get this looked at: Measurably wider than it was last year
- Get this looked at: Water entering through it
- Get this looked at: Leaning strongly toward diagonal and wider at one end
- Get this looked at: Accompanied by sticking doors or sloping floors elsewhere in the house
Reasonable to monitor
- A hairline vertical crack that has not changed in years
- A crack at a basement window corner that stays dry
- Fine surface crazing with no depth to it
- A narrow vertical crack in a house under about two years old with no other symptoms
How it is usually dealt with
Leave it and monitor
Genuinely the correct answer for many vertical cracks. Mark the ends with pencil and the date; if it has not moved in a couple of years, it is very unlikely to start.
Polyurethane injection
Where the crack leaks. The flexible resin fills the wall thickness and tolerates the seasonal movement Calgary imposes.
Epoxy injection
Where the crack is dry and stable and restoring the bond across it is worthwhile. Rigid, so unsuitable for a wall that still moves.
Investigate further
Where the crack is diagonal, displaced or accompanied by symptoms elsewhere, the crack is evidence rather than the problem, and the underlying movement is what needs assessment.
The Calgary angle
The Calgary pattern worth recognising is a vertical crack that is dry for most of the year and weeps during spring melt. That is not the crack deteriorating; it is meltwater arriving faster than still-frozen ground can absorb it and finding the easiest path. The productive response is to look at grading and downspouts before looking at the wall.
What to do next
These cost nothing and make any later assessment considerably more useful.
- Measure the width at the widest point, and photograph it with something for scale
- Run a finger across to check whether the faces are still flush
- Mark both ends in pencil with today's date
- Check whether doors and windows elsewhere in the house have changed
- If it is dry, stable and narrow, note it and re-check in a year
The repair page for this problem
If you have decided it needs attention, this is the page covering what the work involves and what it costs.
Foundation crack repairQuestions people actually ask
Are vertical foundation cracks normal?
Very. Concrete shrinks as it cures and relieves that stress by cracking, usually vertically and often at a window corner. Most Calgary basements have at least one. What matters is not their presence but whether they are wide, displaced, growing or leaking.
How wide is too wide for a foundation crack?
Roughly 6mm, about a pencil width, is the commonly used threshold for wanting a professional opinion. That figure is a prompt to investigate rather than a hard safety line: a 3mm crack that is growing matters more than a static 7mm one, and displacement matters more than width at any size.
Should I fill a vertical foundation crack myself?
Hardware store fillers seal the surface but not the depth of the crack, so water keeps travelling through the wall behind the patch and the repair usually fails within a season or two. The larger drawback is that filling hides whether the crack is still moving, which is the most useful information you have about it.
My vertical crack leaks in spring but not the rest of the year. Why?
Because the water supply is seasonal rather than the crack being seasonal. Calgary snowmelt concentrates a winter of precipitation into a short window, often onto ground still frozen underneath and unable to absorb it. Water runs across the surface, collects against the foundation and finds the easiest path through. That points at grading and downspouts as the first thing to correct.
Not sure what you are looking at?
Send a description and a postal code. It goes to an independent Calgary foundation contractor who can tell you what it is.
We are a referral service, not a contractor. Your request goes to an independent Calgary foundation company.