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When should you worry about cracks in your walls?

Supplier: Mainmark By: James O'Grady
23 December, 2015

Turning a blind eye to wall cracks in your home may mean you’re missing the warning signs for serious and ongoing structural damage.

Wall cracks are common in Australian and New Zealand houses and though some are nothing to worry about, others can indicate a sinking or damaged foundation. If you don’t address problematic wall cracks, the damage to the foundations can quickly devalue your property.

When do wall cracks indicate a structural problem?

Larger cracks that display these characteristics may indicate weaknesses in your property's foundation:

  • One side of the wall is higher than the other
  • Doors and windows no longer close in their frame
  • Cracks are wider than about 5mm (or half a centimetre)

Problematic wall cracks will typically start at windows, doorways or house corners. Generally, smaller hairline cracks are not cause for concern. These are usually the result of seasonal expansion and contraction of clay soils beneath your house over time, and can be easily patched and re-painted.

What causes large wall cracks?

Large cracks may appear because the property's foundation has shrunk or lost its strength, causing all or a part of your house to sink. This usually happens because the moisture in the soil beneath the settled section of your home is either too wet or too dry. In Australia, the CSIRO’s Homeowner’s Guide is a great resource for understanding why your home moves and how to manage the soil beneath its footings. The Queensland Building and Construction Commission also offers valuable advice.

How to fix large cracks in the wall

First, consult a structural engineer to assess the cause of the crack and recommend a solution, then contact the Mainmark team for an initial discussion. The best long-term solution for fixing large cracks is to lift, re-level and re-support your home. This process is called ‘underpinning’. As the house is brought up to towards level, the cracks may close or become smaller (readying plaster or render walls for fine patching and repainting). Windows and doors will also usually begin to work properly again. There are two ways to underpin a home:

1. The traditional method

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

  • time consuming (often requiring weeks or months)
  • messy
  • usually means you’ll have to vacate parts of your home while tradespeople work.

2. The modern method – Uretek® resin injection

A lot like keyhole surgery, this method injects an expanding Uretek® resin into your home’s foundations through tiny 16mm holes. The resin expands to fill in voids and compact soft ground, exerting controlled pressure to raise the home back towards a consistent level. The process is very specific and carefully controlled using laser technology. This method can be a good option because it:

  • rarely takes more than a day
  • doesn’t require you to move out
  • involves no digging (therefore no mess)
  • can be completed around furniture and floor coverings
  • may be carried out from outside the house, so it doesn’t interrupt day to day life.

Mainmark’s Uretek® resin injection technology is a patented and proven method for underpinning homes. It complies with all local, state and national Building Code requirements.