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Do wall cracks indicate a structural problem in my home?

Over time, wall cracks happen–but that doesn’t mean they should be ignored. A wall crack can be an early warning sign of your home’s structural problems.

Sometimes, wall cracks are just a superficial, cosmetic issue. Other times, they indicate deeper structural problems caused by shifting ground, failing house foundations or even poor design and construction.

Are you seeing wall cracks around your home? Concerned there might be deeper issues in your foundations? Read on to learn how to identify the structural wall cracks that spell problems, as well as how they’re caused.

What do structural wall cracks look like?

Stepped Wall Cracks

If you have stepped cracks over 5 mm in width, it’s highly likely your house foundations are no longer stable. Stepped cracks usually indicate that a large part of your home is moving, whether due to unstable brick house foundations or shifting soil below ground.

If you can see stepped cracks, then it’s probable that there are cracked walls in other parts of your home. These cracks are definitely not just cosmetic or superficial. They should be investigated as soon as possible.

Internal and external wall cracks

If you have cracks sitting above your doors and windows, or if your wall cracks are deep enough for light to travel through, then your home is experiencing significant, damaging movement. This movement puts a lot of stress on your home’s foundations and can be caused by foundation failure, soil failure, additional loads or house extensions, or even expansion of the actual brick.

Remember, if you can see straight through a crack, your home has serious structural problems that need to be addressed.

Horizontal Wall Cracks

While stepped cracks indicate mass structural shifts, horizontal wall cracks are a tell-tale sign of localised movement in your home. These cracks are usually an indicator of a foundational failure directly beneath the cracked wall.

Sometimes, horizontal cracks will stop abruptly, which means the wall is sinking at a very specific location. However, even though these horizontal cracks are a localised issue, if they’re not quickly addressed the remainder of your structure will follow suit, sinking and breaking apart as your home’s foundations drop.

Wall Cracks in Corners

Over extended periods, clay bricks (natural product clay) will expand. Sometimes even up to several millimetres per year. Sure, this doesn’t sound like much, but over the decades it’ll all add up, creating a strong lateral force on your structure. This force drives the ends of walls into each other, causing cracks to appear in the corners of your home.

If left untreated, lateral force issues will continue to destabilise your home. Things will get worse and worse until your walls become free-standing, meaning they’re about to topple over.

Stepped Wall Cracks

If you have stepped cracks over 5 mm in width, it’s highly likely your house foundations are no longer stable. Stepped cracks usually indicate that a large part of your home is moving, whether due to unstable brick house foundations or shifting soil below ground. If you can see stepped cracks, then it’s probable that there are cracked walls in other parts of your home. These cracks are definitely not just cosmetic or superficial. They should be investigated as soon as possible.

Internal and External Wall Cracks

If you have cracks sitting above your doors and windows, or if your wall cracks are deep enough for light to travel through, then your home is experiencing significant, damaging movement. This movement puts a lot of stress on your home’s foundations and can be caused by foundation failure, soil failure, additional loads or house extensions, or even expansion of the actual brick. Remember, if you can see straight through a crack, your home has serious structural problems that need to be addressed.

Horizontal Wall Cracks

While stepped cracks indicate mass structural shifts, horizontal wall cracks are a tell-tale sign of localised movement in your home. These cracks are usually an indicator of a foundational failure directly beneath the cracked wall. Sometimes, horizontal cracks will stop abruptly, which means the wall is sinking at a very specific location. However, even though these horizontal cracks are a localised issue, if they’re not quickly addressed the remainder of your structure will follow suit, sinking and breaking apart as your home’s foundations drop.

Wall Cracks in Corners

Over extended periods, clay bricks (natural product clay) will expand. Sometimes even up to several millimetres per year. Sure, this doesn’t sound like much, but over the decades it’ll all add up, creating a strong lateral force on your structure. This force drives the ends of walls into each other, causing cracks to appear in the corners of your home. If left untreated, lateral force issues will continue to destabilise your home. Things will get worse and worse until your walls become free-standing, meaning they’re about to topple over.

What are the leading causes of wall cracks?

Reactive Clay Soil

A major cause of wall cracks is reactive clay. Reactive clay soils move with the seasons, expanding in the wetter months, and then contracting when it’s hotter and drier.

Best case, the soil foundations under your home expand and contract evenly, so you won’t see any wall cracks. However, if external factors cause the soil to expand or contract unevenly, your home’s foundations will experience an immense amount of stress. In turn, you’ll see internal and/or external wall cracks begin to develop.

Additional Loads

Wall cracks appear when the weight of a house goes beyond what it was constructed to support. As your home gets heavier with renovations, wall extensions and other additional loads, the force upon the structure’s foundation, and the soil it sits on, increases. This force can reach a tipping point if it is unevenly directed or distributed. When this happens wall cracks are just the beginning of what you’ll see–it’ll have a devastating impact on the entire structure.

Poor Drainage

Poor drainage is a major cause of wall cracks. Unconnected pipes, broken drains and leakages allow excess water to collect in the soil under your home. Over time, this erodes the soil, leaving voids and pockets of aeration that make the ground unstable. This causes instability and movement in your home’s foundations which, in turn, causes cracks in your walls.

Poor Workmanship

If builders and contractors have cut corners with your home, it’ll come out when the walls start cracking. Poor workmanship is sometimes the cause of your wall cracks, usually appearing if your home was built in a hurry–with a lot of shortcuts. This could come down to neglecting to compact the ground your home is built on, or failing to install quality drainage, leading to soil erosion. There are plenty of jobs when building a home that, if not done correctly, will lead to unstable foundations and the dreaded appearance of wall cracks.

Expanding Materials

Wall cracks can appear when brickwork expands. Some clay bricks can expand up to several millimetres per year as they age over time. This expansion creates lateral force and if it isn’t controlled correctly it causes wall cracks to appear. Wall cracks can also appear in concrete walls. As concrete ages, it can shrink and deflect.

Poor Design

Sometimes, wall cracks are a symptom of the poor design of your building. Australian building codes and standards have changed a lot over the years. So even if it followed best practices at the time it was built, your home may not have been designed to withstand the forces and movements expected in modern environments. It can even happen with newly constructed homes if the proper planning and assessments have not been done. Either way, poor design will lead to instability and wall cracks.
Reactive Soil

Reactive Clay Soils

A major cause of wall cracks is reactive clay. Reactive clay soils move with the seasons, expanding in the wetter months, and then contracting when it’s hotter and drier. Best case, the soil foundations under your home expand and contract evenly, so you won’t see any wall cracks. However, if external factors cause the soil to expand or contract unevenly, your home’s foundations will experience an immense amount of stress. In turn, you’ll see internal and/or external wall cracks begin to develop.

Additional Loads

Wall cracks appear when the weight of a house goes beyond what it was constructed to support. As your home gets heavier with renovations, wall extensions and other additional loads, the force upon the structure’s foundation, and the soil it sits on, increases. This force can reach a tipping point if it is unevenly directed or distributed. When this happens wall cracks are just the beginning of what you’ll see–it’ll have a devastating impact on the entire structure.

Poor Drainage

Poor drainage is a major cause of wall cracks. Unconnected pipes, broken drains and leakages allow excess water to collect in the soil under your home. Over time, this erodes the soil, leaving voids and pockets of aeration that make the ground unstable. This causes instability and movement in your home’s foundations which, in turn, causes cracks in your walls.

Poor Workmanship

If builders and contractors have cut corners with your home, it’ll come out when the walls start cracking. Poor workmanship is sometimes the cause of your wall cracks, usually appearing if your home was built in a hurry–with a lot of shortcuts. This could come down to neglecting to compact the ground your home is built on, or failing to install quality drainage, leading to soil erosion. There are plenty of jobs when building a home that, if not done correctly, will lead to unstable foundations and the dreaded appearance of wall cracks.

Expanding Materials

Wall cracks can appear as materials age. Over time, brickwork expands, with some clay bricks expanding several millimetres per year. This expansion creates lateral force which, if it isn’t correctly controlled, will cause wall cracks to appear. As concrete walls age, they can also start to crack. Unlike brickwork, concrete can shrink and deflect over its lifespan. This creates a similar stress on the structure, triggering the appearance of wall cracks.

Poor Design

Sometimes, wall cracks are a symptom of the poor design of your building. Australian building codes and standards have changed a lot over the years. So even if it followed best practices at the time it was built, your home may not have been designed to withstand the forces and movements expected in modern environments. It can even happen with newly constructed homes if the proper planning and assessments have not been done. Either way, poor design will lead to instability and wall cracks.

Need your wall cracks repaired?

If you’re worried about your wall cracks, our solutions can save you time, money and hassle.
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