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Cracks: Are They Serious?

Posted on 16 July 2015

So you’ve found your dream home. You’ve fallen for the style and layout, the size suits your needs, and it’s in a tree-lined street in a perfect location. Even the price is right, but you noticed some cracks in the external walls. Should you run a mile? Is the house about to fall down? How concerned should you be about these cracks?

Cracks on walls in any building do need be taken seriously. Fortunately, in most cases, they will be superficial and only require cosmetic attention. However, depending on the size and formation of the crack, it could be an indicator of something more serious.

What are the causes of cracking?

There are many factors that can contribute to cracking in masonry or brickwork. They can include:

•    Movement in footings and foundations

•    Expansion and shrinkage due to major changes in weather    

•    Plumbing leaks

•    Tree roots

•    Poor design for soil classification

•    Poor workmanship

•    Age of building

•    Poor ventilation


Cracking can be an indicator of age and wear over time, or something more sinister.

Cracks in older houses versus new houses

Cracks in older houses are more common. They can be purely a result of age, or due to the building being built at a time where less rigid building guidelines were in place. Years ago, soil classification wasn’t taken into account, and footings weren’t as solid.

However, today there are strict guidelines in the National Construction Code detailing how a structure is to be built according to the classification of the soil.
So while cracking in older houses is common, cracks appearing in recently built properties, particularly those less than three years old, could in fact be an indicator of major structural issues and poor build quality.

No matter the age of the property, cracks can be a concern and should be addressed during your building inspections.

What does the size of the crack mean?

When a building inspector checks out your home during a pre purchase building inspection, they will take into account many things in assessing any cracks, including:

•    The size of the crack, classified by the width and length of the crack.

•    The location of the crack, which often indicates the reason as to why it is there. For example, a crack above a window frame could be indicative of a rusted or faulty window lintel.

•    The direction of the crack. Is it vertical, horizontal, stepped, cogged or a combination? This is also a major indicator as to the cause behind the cracking.


According to the National Construction Code and Building Code of Australia, there are standards and tolerances indicating appropriate action on the width of the cracks.

•    Cracks less up to 1mm are generally not an issue.

•    Cracks 1mm – 5mm can be filled or repointed.

•    Cracks 5mm – 20mm indicate likeliness of a more serious issue and should be assessed by an appropriate contractor and/or structural engineer.


The size, location and direction of the crack are indicators of the underlying cause.

So what should you do?

The safest and most reliable way to determine the underlying cause of cracks, and whether cracks in your prospective home are serious, is to do your homework.

Engaging a qualified building inspector to carry out a pre-purchase building inspection is a necessary first step in identifying the cracks.

You then require expert advice on what action needs to be taken, and the cost of remedying the cracks, which you may be able to factor into any price negotiations on the sale of the property. In some cases, you may decide not to proceed with the purchase. Or in the best-case scenario, you’ll discover the cracks are merely superficial, and you’ll be able to buy your dream home with confidence.

Noticed cracking in your prospective home? Contact us now to get a full report from one of our qualified building inspectors to ease your mind.


By Darel McBride


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