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When should you worry about a crack in a house?

Moving ground, bad construction materials, climatic hazards and others are all factors that cause the walls to crack. If some cracks in your house are without great danger, others can compromise the solidity of a dwelling.

This will require knowing how to recognize them and knowing their origin in order to better intervene. What are the different types of cracks? How to recognize them? When and how to act? What steps should be taken to limit their occurrence? So many questions to which we will provide answers.

How to identify cracks and their level of danger?

A crack is a kind of split that affects either the wall or the floor or the ceiling of a building. If most of the time, they are benign, it will always be necessary to be wary of them. Some of them, depending on their appearance, can be dangerous.

a crack in a house wall
A crack in a house wall


The microcracks are located in the joints of the masonry. Very fine, they are due to the use of poor quality or incorrectly dosed armature. With an amplitude of less than 0.2 mm, they are all superficial, which is why they are easily identified.

A microcrack is not very dangerous, but it can favor the passage of water, thus creating humidity problems. When they appear, it is recommended to call on a waterproofing professional to solve the problem very early on, since, over time, water infiltration may be significant and damage the wall.

Fine cracks

Fine cracks are at least 2 mm wide. This type of crack can be created in a wall by a shock or a not too dangerous foundation movement. They affect, in addition to the surface coating, concrete blocks, bricks, stones and others. They are often found at stairs, around the edges of doors or windows.

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Like microcracks, fine cracks are harmless until they grow, or multiply. In the worst case, they can turn into cracked walls, becoming very dangerous.

Deep and dangerous cracks

When the crack that appears in a wall exceeds 2 mm, it is qualified as deep or dangerous. Beyond 2 cm, deep cracks are qualified as cracked, and must be treated urgently. They are caused by ground movements such as settling or subsidence of the ground and highlight the extreme fragility of the foundations of the house. Most end up on the stairs, as they follow the path of the cinder blocks.

These cracks cause in the best case the infiltration of water and humidity. However, they can lead to the collapse of an entire building, if measures are not taken quickly.

It is very important to monitor the cracks as soon as they appear, as they can hide other more serious problems. A simple crack, in appearance, can hide a structural problem that could compromise the general balance of an entire home.

What causes cracks to appear in a wall?

Whether deep or not, internal or external, cracks can have several origins. They are most often caused by these ailments:

Ground instability

Certain types of soil, such as clay, are subject to natural phenomena of shrinkage and swelling. When not considered in the structure and foundation of the house, ground movements cause stresses on buildings. This is what causes cracks in the facades and walls of houses.

Construction defect

This is the most dangerous cause which, moreover, can compromise the entire structure of a dwelling. It concerns houses that are built without a crawl space or basement and whose foundations are shallow.

During construction, in most cases, anchoring and stiffeners are insufficient or even absent. Or, the properties of the soil are not studied and the foundation measurements are neglected.

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Water seepage

The facade of a house weakened by bad weather and rainwater becomes permeable to water. With the onset of freeze/thaw cycles, the walls give way and reveal cracks.

The shocks

Shocks can be direct or indirect. These are respectively cases of accidents or earthquakes.


Subterranean subsidence or collapse affects the structure of the house, causing cracks to appear.

Construction nearby

Before building a house near another, it is essential to dig holes. As these holes are dug, they can cause repeated vibrations or subsidence of the ground, which weakens the foundations of the surrounding houses and leads to the formation of cracks.

Cracks are common and it is not just these causes that cause them. No region is spared, even those that are unlikely to be at risk of cracks. It is therefore important to know when to act and how to go about it.

crack in the facade of a house
Crack in the facade of a house

When and how to act in case of cracks?

Cracks, whatever their nature, should alert, even if the most superficial are not a source of danger. It is important that you remain vigilant once they appear in order to follow their evolution closely. Stop intervening at the right time.

When to act?

It is not so easy to determine the dangerousness of a crack, especially when it is still in the initial phase. However, here are some signs that may alert you:

  • The cracks that already exist are widening;
  • New cracks appear;
  • Water infiltrates easily causing humidity problems;
  • The plaster falls, the slabs move, the tiles are cracked and others;
  • You hear crackling;
  • The general condition of the building is deteriorating.

In either of these cases, it is recommended to call in the professionals. Before the arrival of the latter, you can intervene yourself when the situation allows.

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How to do it

Faced with dangerous cracks, it is best not to intervene and let the expert come and do his job. Moreover, your home insurance can solve the problem by reimbursing you. Treatment of deep cracks is quite a complex process. To find the best solution, the expert must first understand the origin of the crack. When you intervene against a crack, you will just close it, but the problem will not be solved.

If you are dealing with a micro crack or a superficial crack, you can fill it yourself. Before intervening, observe it closely for a few weeks. If it remains at the superficial stage, apply quality filler to fill it. Otherwise, contact an expert, he will be able to tell you what to do.

Some tips to prevent cracks

Before building, the study of the soil is an essential step. It is used to collect information about the composition of its layers, its density, its resistance and others. This makes it possible to adapt the foundations of the house to the nature of the ground which hosts it.

Note that you can only limit cracks, but not avoid them. To do this, before acquiring a home, make sure that the agglomerate blocks and the chaining are made in accordance with the standards in force.

Cracks in the walls of a building are quite common. While there are some that aren’t too dangerous, others can cause an entire building to collapse. It is therefore important to identify them and determine their origin in order to intervene at the right time, and in the right way.