Don't wait on a crack that is growing. Sudden, widening, horizontal, or displaced cracks need a professional evaluation soon.
Usually harmless
- Hairline cracks, which often form as concrete cures and shrinks
- Some vertical or diagonal cracks from normal settling. Direction alone doesn't tell you how serious a crack is.
Warning signs that call for a professional
- A crack wider than 1/4 inch
- Horizontal cracks, which can mean pressure building up outside the foundation
- A crack where one side sits higher than the other
- Doors or windows that suddenly stick, rub, or won't close
- Sloping floors, or gaps that widen between walls and ceilings or around door frames
- Bowing walls, or water entering through the foundation
- Any crack that appears suddenly or keeps growing in width or length
Monitor a crack: a simple monthly check
- Photograph the crack with a ruler in the frame, and note the date.
- Measure the width at its widest point with a ruler or a crack gauge.
- Mark each end of the crack with a pencil and the date.
- Repeat monthly for three months, and again after heavy rain.
- Note any changes in nearby doors, windows, or floors.
When to call a professional
Call a structural engineer or foundation specialist if you see any warning sign above, or if your monitoring shows a crack growing. Have any stair-step crack pattern assessed too. Keep your photos and measurements with the report.
Sources
This guide is based on the following sources. Requirements change, so check the originals and your local building department before you start.
This guide is general maintenance information, not a substitute for a licensed contractor's inspection. Follow the manufacturer's instructions and your local code requirements.