What is Crack Stitching?
Crack Stitching is usually carried out to reconnect brickwork or masonry that has cracked due to unknown reasons. It is one of the most popular and practical methods to fix cracked walls that require structural repair. Crack stitching uses bars grouted into the bed joint overlapping the cracks in the wall, joining them together during the process. Compared to other repair methods, crack stitching is cost-effective and resilient.
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Causes Of Cracked Walls
Subsidence is a sudden sinking or downward movement of the ground with no horizontal motion. The situation may occur due to cohesive soils shrinking and swelling, soils being washed away, movement of varying soil structures, and more.
Settlement is the downward settling of the surface due to the loading of the building built upon the ground. Settlement occurs due to the wet ground conditions, shifting soil conditions, water pipe leakage, unsupported foundations, etc.
Both the conditions are responsible for cracked brickwork/masonry.
2. Trees and Drains
The growing roots of a tree near the foundation of a building or a wall absorbs water from the substrata, especially from clay soil. These evolving roots require space to spread more, resulting in huge cracked lines. In addition, drains are heavily affected due to a sudden ground movement or tree root interference. This in turn causes soil erosion or softens the clay soil, affecting the structural capabilities of the foundation to handle the weight of the building or wall.
3. Inadequate Foundations
Most older buildings or walls fail to support the loading of the structure, resulting in either a collapse or a cracked foundation. Cracks may also occur due to shallow strip foundations, shifting soil conditions or poor ground conditions.
Opposite to subsidence, heave is the upward movement of the ground beneath the buildings due to soil expansion. It is usually associated with clay soils that have dried and then rehydrated, resulting in volume expansion of the soil. One possible cause of heave is when the ground on which the building stands absorbs too much water and expands. The most common cause of heave is associated with trees that have been removed or died.
5. Thermal Changes
All construction materials have varied properties related to expansion and contraction. Two of the most common reasons are changes in the temperature and moisture content of the construction materials. Both factors can result in fractured or bulged brickwork.
6. Roof Load
Sometimes, the extreme weight of the roof spread can impact the foundation, burdening the structure and vertical walls. Due to insufficient roof lateral or restraint, cracks may occur between the internal partition walls and the external.
7. Lintel Failure
Lintel failure in a building structure is often caused by corrosion, decay, or inadequacy. The structural failure of lintels can result in diagonal cracks above the wall openings.
How is Crack Stitching Carried Out?
The process of crack stitching includes inserting long narrow metal bars into the bed joints of brickworks and grouted into one place. It is as follows:
- To create a gap in the bed joint, two deep chases are made into the mortar. Both the deep chases are carefully cleaned to remove dust and debris.
- Once cleaned, a bead of grout is injected inside both chases.
- Premium quality stainless helical bars are cut down to the appropriate size. The size should fit into the bed joint.
- These bars are then placed into the bed joint and pushed deep into the grout. The second bead of grout is applied on top of the first layer.
- Once in place, use mortar to conceal the crack.