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Walls of a new house or old house, all end up more or less by cracking. All constructions are anchored in the ground on foundations. But even the most stable soil moves. Moreover, the forces exercising on the construction also make it move. And cracks appear... Knowing how to recognize the different types of cracks will allow you to determine those that are only aesthetic of those that are dangerous and compromise the solidity of your home.

The different types of cracks in a wall

The different types of cracks in a wall


Those are narrow cracks, filiform less than 0.2 mm wide.
On an exterior plaster, they may appear as a tight network of cracks in certain areas of the facade. We are talking about crazing. At this stage, they only concern the surface layer of the coating.

On the other hand, there is really talk of microcracks when they attack the coating all the way through:

  • Microfissures of withdrawal: They are presented as the crazing or at the joints of the masonry. The problem comes from the plaster and the joints themselves (too much mixing water, poor mortar quality, poor adhesion of the plaster).
  • Horizontal or vertical microfissures: they are often due to the hygrothermal behaviors different from the materials composing the wall. For example, junction between the blocks and a poured concrete lintel or a reinforced concrete chaining

Although superficial, they are to watch because they can cause water infiltration under the coating and damage it. It should also be ensured that this is not in fact an important structural crack which under the weight of the masonry has closed again...

Fine cracks

They are between 0.2 and 2 mm wide. They may concern only the thickness of the plaster or may also concern the masonry. Their locations often determine the cause of their appearance.

  • Mustache cracks: Oblique or vertical, they start from the corners of windows or doors. They are due to a weakness of the masonry at the level of the supports of the openings.
  • Vertical cracks at the corners of the building: they come from a vertical chaining fault.
  • Horizontal cracks at floor levelThey signal bending or removal of the floor slab.

It is important to check their stability over time. Depending on its cause, a superficial crack may evolve into a larger crack.

Big cracks and crevices

A large crack is more than 2 mm wide. When it reaches 2 or 3 cm, it is called lizarde. They are the consequences of an instability of the ground (phenomenon of shrinkage-swelling of certain clay soils for example) or movements of the foundations or materials (structural cracks).

  • Through cracks: They cross the wall on both sides.
  • Stair crack: They follow the joints of the blocks, bricks or stones that make up the wall.

They must be examined carefully by a professional. Because it is the stability of the building that can be questioned and sometimes quickly. They require the installation of witnesses who will measure their evolution.

Large cracks can also be a source of serious moisture problems in the home. If the water enters the crevice, it is called infiltrating crack. In addition, this moisture trapped in the wall will freeze the winter and gradually enlarge the crack.

In any case reseal a crack without knowing the cause or causes is perfectly ineffective. It will open again or another will appear next door...

Video Instruction: Part I: Types of Cracks and Their Causes