Cracks In The Walls: Should You Worry?

huge crack in brick wall

When we see cracks in the walls of our home, some of us might not think it’s something to worry about.

Unfortunately, cracks in the walls can be a sign of structural problems. When neglected, they can cause severe damage to your property and endanger the safety of those living there.

It’s important to understand that you have to take them seriously when they appear. Make an effort to find out the possible causes of wall cracking, learn how to prevent them, and find out what to do when you see the first signs of damage.

What is it?

Wall cracking is the breaking apart of a non-flexible part of your property, causing cracks, which can open or close according to the force that caused it.

Types of cracks in walls

There are three types of wall cracking:

  1. Interior wall cracking – those that occur in the gyprock or plasterboard
  2. Exterior wall cracking – those in the brickwork or surface of the external wall
  3. Foundation cracking – the cracks in the concrete foundations below the ground

All of these forms of cracking can result in structural failure depending on the location, orientation (horizontal, vertical or jagged), the connectedness of the wall to the house framework, and the cause of cracking.

When to worry about cracks in brick walls

Stepped cracks in brickwork
Stepped cracks in brick wall

If you have a brick wall and there are stair-step cracks (stepped cracks in brickwork) along the mortar joints, then it’s a sign of a defect on your exterior wall.

On the other hand, a gaping crack means that there’s a much more serious problem with the structure.

The Causes of Wall Cracking

To determine the extent of the problem, you have to determine what has caused the cracks to appear.

Below are the most common causes of wall cracking.


Subsidence is the extreme movement of the ground that supports the structure. Cracking will occur when the movement’s intensity and direction differ at various parts of the property.

Subsidence may occur when the soil compresses due to the property’s weight. It can also be caused by contracting and swelling of the soil from varying moisture content.

The problem of subsidence in residential properties is addressed by the Australian Standard AS2870 – 2011 Residential slabs and footings, by setting a standard on footing design and construction.

It involves:

  • footing system selection,
  • site classification,
  • structural design,
  • correct building process and
  • proper maintenance.

Subsidence can be further prevented by maintaining your property drainage, avoiding any alteration to the drainage system, refraining from placing a garden too close to your home and planting trees near the property.

You can also prevent subsidence by regularly checking and maintaining your home’s drainage and plumbing. Any damage should be repaired immediately.

Settlment Cracks in Brick Walls

crack in brick wallThis is a process that takes months or years to occur but can still cause cracks in the walls.

It happens when the disturbed soil from the excavation process becomes compacted and settles down, causing movement in the structure.

The movement, subsequently, results in wall cracking. The narrow vertical cracks often found in the walls are caused by natural settling of the soil.

Minor settling is a normal occurance and occurs over time.

Subsidence is when a significant movement in the soil occurs.

Clay and Other Reactive Soils

Reactive soils expand intensely when moist and contracts extensively when dry, causing large movements on the structure. Gravel and sand are also some good examples of reactive soils.

Before purchasing a property, you need to have the soil tested first to make sure that it isn’t reactive.

Climate Changes

The seasonal changes of climate in your area from wet to dry and back again will cause the soil to expand and contract.

These can also cause cracks in the walls of your property.

Poor Property Design and Construction

Under-engineered footing, inadequate excavation and weak load-bearing walls can result in wall cracking. Sub-standard building materials and construction process also contribute problems. Making sure that everything is properly completed during the design and construction of your home is crucial. A private building certifier can conduct a site inspection at the final stage of construction and issue the final certification documentation.

Water Damage

Cracks in the walls can also be caused by damage from the water surrounding your property. That includes water from garden sprinklers, leaking pipes, blocked drainage and flooding.

Construction or Excavation Work

If your home is located near a construction area or quarrying site, then it can be prone to wall cracking as well. The vibration brought about by excavation and use of machinery can cause movement of your walls, creating cracks internally, externally and even with the foundation.

QBCC & MBA on Subsidence

Subsidence is one of the leading causes of wall cracking and can cause the most significant problems structurally. For this reason, in Australia there are strict regulations revolving around the building and construction of properties in order to help prevent major issues from occuring. These regulations may vary from state-to-state, but they all adhere to the provisions of the Building Code of Australia (BCA). The Queensland Building and Construction Commission (QBCC) is the regulatory body for the state of Queensland while Master Builders Association (MBA) NSW oversees building and construction regulations in New South Wales.

According to the BCA, cracks that measure less than 5mm in width and can easily be filled do not require repair. They are acceptable and compliant to the Standard. Meanwhile, cracks in the walls wider than 5mm are not compliant and require whole or partial replacement of the wall.

QBCC diagram on local change of slope

The local change of slope from either horizontal or vertical that is in excess of 1/100 to subsidence is unacceptable. You should contact your builder right away and have it remedied. Houses that were built within the last 6.5 years may be covered under warranty.

If you are not happy with your builder’s response, you can always lodge a claim with the QBCC and MBA. The property will be assessed with an inspection to determine the severity and who is responsible to correct the issue. Should the movement prove to be non-compliant with the Australian Standard, the appropriate state regulatory bodies will propose a solution to solve the problem.

How to Prevent Subsidence

Natural subsidence can cause cracks in the walls of your home and sometimes these things can’t be avoided, such as subsidence due to climate changes, however measures can be taken to minimise the risk. This includes steps such as:

  • maintaining your property drainage,
  • avoiding any alterations to the drainage system,
  • refraining from placing a garden close to your home, and
  • not planting trees near the property.

You can also prevent subsidence by regularly checking and maintaining your home’s plumbing and stormwater systems. Any damage should be repaired immediately.

What to do if you notice wall cracks?

You should act immediately upon noticing the presence of wall cracking, especially if the cracks are more than 5mm in width.

Hairline cracks can easily be sealed with paint or filler, but wider cracks require more significant repair work and the costs/damage will get worse if not addressed quickly.

Some examples of repair work include:

  • Restumping – Replacing old stumps that may have been damaged due to corrosion, rotting or termites.
  • Underpinning – Bringing up your house to its original level by stabilising the footings. This involves excavation of the foundations and injecting new concrete.
  • Rebuilding – More severe cases of wall cracking may require demolition of the wall and rebuilding it.

To determine the severity of your wall cracks and the best method of repair for your property, it’s highly advisable that you get a professional building defect inspection as soon as possible.

The repairs may involve your builder, plumbers or tree loppers, so you will need a building expert’s advice to find out which services are essential.

Contact Us for an Inspection

For a building defect inspection in Queensland or New South Wales, contact the experienced and qualified team at iCertified.

We provide comprehensive building and safety defect reporting to ensure a property’s compliance with the BCA and state standards.

Contact iCertified for advice today.