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The majority of all structures crack, but when should you become worried? Most houses in South Africa will eventually develop wall cracks. Nearly all of these cracks aren’t serious and is attributed to a slight settlement of the foundations, mortar shrinkage, or small roof movement. However, some cracks can be potentially dangerous and are the consequence of significant foundation displacement, water infiltration, or extreme roof movement in which case crack repairs are necessary.
Types of cracks:
Settlement takes place as the house “settles” on top of its foundation, which frequently leaves diagonal cracks stretching upwards from window and door frames in its wake. Cosmetic fixes such as new paint or crack repair are not going to resolve problems brought on by expansive soil permanently.
Temperature changes, the sun heating and expanding the bricks, usually results in the bricks applying more pressure on one another than before and can lead to vertical or stair step cracks.
Water damage cracks
Water penetrating walls from above will result in cracks lower down since the water is pulled downwards through the wall and searches for an exit from the brickwork when coming across a dense barrier like a concrete slab or waterproofing.
Roof movement cracks
Movement of the roof framework, where it sits on the wall plates across the tops of the walls, may also cause wall cracks. These cracks are often minor and can be spotted along the line of the ceiling and cornices. Roof movement results from badly braced rafters and trusses which can exert outward pressure on the tops of load-bearing walls. Weak anchoring of the roof to the walls can also lead to roof movement – especially in windy areas.
Cracks in plastered walls tend to be common, particularly in older houses. Plaster cracks can result from strains brought on by movement. Cracks in plaster can be caused by improper plastering techniques or plaster that has been permitted to dry too quickly. One of the greatest reasons that plaster may crack is caused by adjustments to ambient moisture levels and different enlargement coefficients between mortar plaster, bricks, cement and steel.
The basics of repairing cracks are to remove all debris and excavate the crack down to durable material. Subsequently, an appropriate, versatile, crack filler or mortar mix are often used to fill the crack.
If believed that the crack has occurred as a result of movement that is likely to carry on then an effort can be made to strengthen the wall across the cracked part. This can be accomplished by enhancing the plastered area with a metal or plastic mesh or by a method known as “metal stitching”. In this case, lengths of metal rod are fixed across the crack with