Found a crack in your wall or floor and wonder if you should panic? Most cracks are harmless, but a few can signal serious structural trouble. Knowing what to look for, how to measure, and when to call in an expert will save you time, money, and stress.
First, figure out where the crack is. Is it on an interior plaster wall, an exterior brick façade, a concrete floor, or the foundation? Location tells you a lot. Horizontal cracks in foundations often point to pressure from soil, while vertical cracks in walls are usually shrink‑age or settlement.
Grab a ruler or a crack‑width gauge and note the opening. A crack under 1 mm (about the thickness of a credit card) is usually not a problem. Anything over 3 mm – especially if you can see a gap – should raise a red flag. Write down the measurement and the date you first noticed it; tracking changes over weeks or months helps you see if it’s growing.
Look for patterns. A single thin line that stays the same size is less concerning than a network of cracks that spread across a wall. Also, check for moisture stains, damp spots, or mold near the crack – water can speed up damage.
Don’t forget the ceilings. Cracks that start at the top of a wall and angle downwards often mean the floor is moving. In a new build, a few hair‑line cracks may simply be the building settling; they usually stop after a few months.
If a crack is wider than 3 mm, appears suddenly, or is getting bigger each month, call a structural engineer. They’ll inspect the site, possibly use a laser level or a crack monitor, and give you a written report. The report will tell you whether the crack is cosmetic or needs repair.
Foundation cracks that are wider than 5 mm often need specialist repair. The most common fix in the UK is injecting epoxy or polyurethane, which fills the gap and restores strength. For larger gaps, underpinning or installing a concrete “cushion” might be required. Costs vary, but a typical small foundation repair starts around £1,500 and can rise to £10,000 for extensive work.
For wall cracks, the solution is usually simpler. Re‑plastering or applying a flexible filler works for minor cracks. If the brickwork is affected, a mason can tuck in a brick or use a breathable sealant. In most cases, the repair can be done within a day or two.
Before any work starts, ask the contractor for a detailed quote, timeline, and warranty. A reputable builder will explain why they chose a particular method and how they’ll protect surrounding areas.
Finally, keep an eye on the repaired area. If the crack reappears or new cracks show up nearby, it could mean the underlying issue wasn’t fully solved. Regular inspections, especially after heavy rain or ground movement, are a good habit.
In short, not every crack means disaster, but a quick check of size, location, and change over time will tell you when to act. Measure, record, and don’t hesitate to get a professional opinion if anything feels off. Your home will stay safe and sound, and you’ll avoid costly surprises down the line.
Building a new house can be exciting, but discovering cracks can be alarming. Not all cracks are the same—some are harmless, while others might indicate structural problems. Understanding the types of cracks and their causes can help homeowners address issues effectively. This article covers common reasons for cracks in new builds and offers tips to identify and fix them.
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