big wall crack

Wall cracks in your home – 3 signs to look out for and how to address them

Wall cracks are common in UK houses. In most cases they are not necessarily a reason for concern, but some cracks can indicate more significant issues. When identifying the cause, seriousness and possible solutions for cracks in a home, the type, size and location are critical.

If the underlying cause of problematic wall cracks isn’t addressed, such as damage to a building’s foundations from subsidence, the property could quickly devalue and affect insurance premiums.

When do wall cracks indicate a structural problem?

Small, hairline cracks are common and not usually concerning. These are often the result of seasonable expansion and contraction of soils beneath a structure’s foundations over time. These types of cracks can usually be easily patched over and repainted.

However, larger cracks that display the following characteristics may indicate weaknesses in your property’s foundation and mean that you should seek expert advice:

  • Large cracks that start at windows, doorways or corners of buildings
  • Cracks are wider than about 5mm (or half a centimetre)
  • Cracks that are jagged, horizontal or vertical, zig-zagged, stepped in brickwork, or follow mortar lines

Pay attention to other warning signs such as sinking or sloping floors, cracks in paths and driveways as these may be signs of structural issues caused by subsidence. Windows and doors becoming jammed or misaligned, skirting boards separating from the wall or the formation of puddles around the perimeter of your home may also indicate foundation ground issues.

How to fix large cracks in the wall

The best long-term solution for fixing large cracks is to re-support your home. This process is called ‘underpinning’. Solutions to consider include traditional methods like concrete underpinning, or non-invasive resin injection, which is comparatively much faster and usually more cost effective.

Before choosing a solution, the first step should always be to consult an expert such as a structural engineer to assess the cause of the cracks and recommend a solution. The types of underpinning methods are:

The traditional method

This involves excavating or digging up parts of the foundation, pouring in concrete, waiting for it to set and then lifting the house off the concrete blocks. However, this method can be:

  • time consuming (often requiring weeks or months)
  • usually means you’ll have to vacate your home while tradespeople work
  • disruptive to yourself and neighbours
  • messy and intrusive

The modern method – Teretek® resin injection

In a process very similar to keyhole surgery, an expanding Teretek® resin solution is injected under the home’s foundations through very small holes. The resin expands to fill in voids and compact weak ground, exerting controlled pressure to help raise the home back towards level. The benefits of this are:

  • usually completed within a few hours; rarely takes more than a day
  • doesn’t require you to move out
  • requires no digging and therefore no mess
  • can be completed around furniture and floor coverings
  • often carried out from outside the house, so it doesn’t interrupt day to day life

As the building is brought up towards level, the cracks may close or become smaller (plaster or render walls can then be patched and repainted). Windows and doors will also usually begin to work properly again.

Mainmark’s Teretek® resin injection technology is a tried-and-tested, quick and reliable method for underpinning homes as seen in this Oxford home. For more information and advice, please call 0800 9750507 or visit