Foundation Cracks: What to Look For and How to Deal With Them
Seeing a line in your wall or floor can be unsettling. Most homeowners wonder if it’s just a harmless hairline or a sign of big trouble. The good news is you can tell the difference yourself with a few easy steps.
Measure the Crack – Size Matters
Grab a ruler or a cheap digital caliper. If the crack is under 1 mm you’re probably fine. Anything wider than 3 mm should raise a red flag, especially if it’s growing. Write down the width and take a photo every month. A crack that stays the same size for three months is less likely to be structural, but one that widens quickly needs attention.
Location matters too. Cracks that run vertically along a load‑bearing wall, or those that appear around doors, windows or the foundation footing, are more serious than a random hairline in a non‑load‑bearing partition.
When to Call a Structural Engineer
If you spot any of these, give a professional a ring:
- Crack wider than 3 mm and still growing.
- Diagonal or stair‑step cracks in brickwork.
- Cracks near the base of walls or around the foundation.
- Signs of movement like doors that stick or uneven floors.
A structural engineer will inspect the problem, maybe take a few core samples, and give you a written report. That report is your ticket for insurance claims or negotiating with sellers if you’re buying a house.
Don’t wait for the crack to double in size. Early action can save hundreds or even thousands of pounds in repair costs.
Quick Fixes You Can Do Now
For minor hairline cracks, a simple epoxy filler works well. Clean the crack, apply the filler with a syringe, and smooth it with a putty knife. Paint over it to match the wall. This won’t stop a big structural problem, but it will keep moisture out and stop the crack from getting worse.
If the crack is close to the ground, check the drainage around your house. A blocked gutter or a sloping yard can push water toward the foundation and worsen cracks. Make sure rainwater flows at least 1 m away from the walls.
Keep an eye on any new cracks that appear after heavy rain, frost, or after any big construction work nearby. Those are clues that the ground is moving and you may need a deeper investigation.
Bottom line: measure, record, and act fast. Small cracks are usually easy to manage, but bigger ones need a professional’s eye. With the right steps you can keep your home safe and avoid costly surprises down the line.
