There are few reasons of cracks getting developed on a wall .Therefore it is quite essential that we take certain precautionary measures while constructing.
Ceiling deflection and movement – A ceiling above a partition wall may deflect under loads applied after its erection, or through thermal or other movements. To avoid cracking as a result of such deflection, the partition wall shall be separated from the ceiling by a gap or by a layer of lean mortar.
Deflection or movement of structural abutments -Walls, columns or other structural elements against which a wall or partition abuts may deflect or move because of load, settlement, shrinkage or thermal effects. In order to avoid cracking of walls or partitions as a result of such movements, a slip joint shall be provided where possible, preferably packed with a resilient material or lean mortar.
Cracks in partition walls may occur at the corners of door frames and window frames at lintel level or sill level. It may, therefore, be desirable to provide a nominal reinforced concrete bond beam at sill level and vertical reinforced concrete stud at either side of vertical members of frames which may in addition provide sufficient anchorage for the holdfast.
Control of Wall Movement Accompanying Temperature and Moisture Changes –
Cracking in concrete masonry walls is often due to tensile stresses which develop when wall movements accompanying temperature and moisture change are restrained by other elements of the building, or when concrete masonry places restraint on the movement of adjoining elements.
There are three methods of controlling cracking in concrete masonry structures:
a) Specifying a limit on the moisture content of masonry units at the time of delivery and construction,
b) Incorporating steel reinforcement either in the form of nominal bond beams or horizontal joint reinforcement, and
c) Providing control joints to accommodate the movement
In all concrete masonry construction it is essential to employ only moisture-controlled units. Their use, combined with the provision of control joints, is generally adequate to prevent cracking in concrete masonry walls. However, bond beams or joint reinforcement, or both in different locations as considered suitable, may also be used in addition to the above.