How to repair and prevents cracks in walls

A wall crack can sometimes indicate foundation failure and may need to be checked by a structural engineer. There are many reasons behind what can cause cracks in walls. It is important making notes as to when any new cracks appear, take measurements and monitor overtime. Let’s see why cracks appear and how to fix or repair cracks in walls.

Types of Cracks and causes in walls

1. Stepped cracks

stepped cracks in walls

Cracks appear as stepped, indicating settlement cracks. These can be fixed by your local masonry/general builder.

Repair: How to repair stepped cracks in walls

2. Vertical cracks

Vertical Cracks in Walls

Vertical cracks that appear anywhere on the wall can be caused by thermal expansion; due to the sun heating the wall they may expand and crack. Moisture that freezes can induce something known as frost thaw, which also causes cracks in walls in rainy or cold regions.

Repair: How to repair vertical cracks in walls

3. Improper lintels

Improper Lintels Cracks in Walls

There are so many types of lintels; some of them are made from metal, and some of the others, therefore, can expand and contact. This type of failure causes cracks around the top of windows and doors. Other cracks above openings could be because of inadequate props when removing and adding new windows/doors, extreme loads directly above the opening, or alternative use of lintels.

4. Mining activity

Suppose there has been mining activity for a long in the past. In that case, there may be shafts that are still there but liable to collapsing (not only makes the load-bearing capacity of the soil weaker), but could it was to collapse while the building was there, then the structure would ‘plummet’ in some sense and cause multiple cracking suddenly.

5. Leaking underground drainage

Leaking underground drainage may cause the soil to contain more moisture and expand the land around the foundation’s “bulb of pressure,” leading foundations to fail and walls to crack.

6. Tree root activity 

Tree root activity can be another cause when tree roots take in more water, leading to ground shrinkage, or extracting trees can cause moisture content to build up.

That is why a good and proper soil investigation shall need before planning to build a structure.

Factors that are affecting the crack

On brick walls, there are a lot of factors playing a role in causing the crack in the wall that may happen in the future. You can classify them into three simple categories.



Structural factors play a significant role in causing cracks in the wall. Not only walls, if there is structural instability, but your whole building may also collapse. So for a stable construction, one should remember these points to avoid structural instability:

  • Build a strong foundation
  • Consolidate the soil if necessary; otherwise, uneven settlement may cause load concentration on one side of the building and crack.
  • If the water table is too high, give adequate damp proof coarse.
  • Ensure soil investigation is done, and always check the soil type before construction. Then if ground improvement is needed, do it before constructing the foundation.
  • Always give enough time to cure each structural part, and their uniformity is crucial.



Undeniably, if we use low-quality materials, our walls will crack. But apart from it, we should keep several other factors in mind.

  • Always use water between a pH scale of 6.5–8.5
  • The mortar should be applied according to the W/C ratio with desired consistency (neither too dry nor too wet; just the desired water for enough consistency).
  • The fine aggregate and cement ratio should be the preferred standard (generally 1:5 or 1:6 for walls).
  • Cement should be appropriately stacked, and cement should immediately be rejected if lumps are formed.
  • Ensure the brick should be free of alkali salts which may lead to efflorescence.



If you get everything right, an unskilled and inexperienced workforce can put all your money in vain. The thing that should be followed to avoid it is:

  • Hire good masons (Not less than 03 years of experience).
  • Tell them clearly about the specification of the proportion of cement, sand, and water and how you want them to do the work. (in short, prepare a method statement yourself)
  • Check regularly if the walls are cured properly. Curing is a crucial part of the hydration of cement.
  • Before construction, soak the bricks in water for at least six hours. This will reduce the need for curing and let the hydration happen smoothly.
  • Do not allow the mason and other helpers to keep the mortar in place after mixing for a long time (more than 30 minutes). This will prevent the cement from setting and sticking.

There are a few sure-shot ways to prevent cracks in brick walls.

Take notes and remember them, and you’ll be fine in the long run.

1- You should always use quality materials like mortar and concrete from a reputed seller.

2- You should ensure that the concrete, mortar, and water-cement ratio is as per the design.

3- You should never build a foundation on muddy or loose soil, as it would not hold the same position in the long run.

4- You should see to it that all parts of every structural building should be constructed uniformly.

5- You should avoid laying the foundation of a building in extreme weather conditions like excessive heat or cold weather.

6-You should only trust experienced workmen for the job as newcomers may make more mistakes and destroy the entire project.

7- You should confirm that the foundation of a building is completely dry before building more.

Many other things can be added here, but everyone should remember these most common things to avoid cracks in a brick wall.

Repair of cracks in walls

Number 01.

  • Hairline cracks of less than about 0.1mm are classified as negligible. No action is required.

Number 02.

  • Fine cracks can be treated easily using the standard decoration method.
  • Damage is generally restricted to internal wall finishes; cracks rarely visible in the external wall. Regular crack widths are up to 1mm.

Number 03.

  • Cracks easily filled. Suitable linings can cover recurrent cracks.
  • Cracks are not necessarily visible externally; some external repointing may be required to ensure weather tightness.
  • Doors and windows may attach slightly and require easing and adjusting.
  • Regular crack widths are up to 5mm.

Number 04.

  • A mason can patch cracks that need some opening up—repointing exterior brickwork, and possibly replacing a small amount of brickwork. Doors and windows are sticking. Service pipes may fracture. Weather tightness is often impaired. Regular crack widths are 5 to 15 mm, or several of, say, 3 mm.

Number 05.

  • Extensive crack requires breaking out and replacing sections of walls, especially over doors and windows.
  • Windows and door structures are distorted, floor slopes noticeably.
  • Walls are bending or bulging noticeably, with some bearing loss in beams.
  • Service pipes disrupted.
  • Typically crack widths are 15 to 25mm, But it also depends on the number of cracks.

Number 06.

  • Structural damage that requires a crucial repair job involves partial or complete rebuilding.
  • Beams fail to bear, walls lean badly, and require shoring.
  • Windows were broken with distortion.
  • Danger of instability
  • Typical crack widths are at least 25mm or more but depend on the number of cracks.


The first three types of cracks – 1, 2, 3 – only require redecoration and no significant work. The cracks described in 3 and 4 require more major work. Still, it is only the fifth type of crack which indicates intensive structural damage and needs urgent attention from a professional engineer or surveyor.


It is crucial to point out that even with more minor cracks, you should monitor them over time in case they increase in width. Any increase could be indicative of a more severe underlying issue. Those cracks that emerge over a short time, even small ones, are also possible causes of concern compared to those that have been there for years.

Confer a professional structural engineer to confirm any diagnosis and an appropriate course of action. 


Important things to remember.

If you consult a structural engineer or building professional, they will ask you to know the following:

  • How long have the cracks been there?
  • Are they getting wider?
  • Are they increasing in number?

It is crucial making notes as to when any new cracks appear and take measurements. A pencil or marker line can be drawn across the crack to monitor its movement.