The most obvious reason for cracks is settlement. Settlement does not only mean that foundation gets settled and it leads to cracks in building.
Settlement is a very large term and is not only limited to the foundation. It can also occur because of material you have used for brick masonry. If curing of brick masonry not done proper before plastering, then it also leads to cracks in walls.
Every material has specific curing time. Walls should be cured minimum 7-days before any other activity. Areas where temperature is high, need curing of exposed areas directly to sun light after every two hours.
Make sure water in binding material only used for bond formation and not become a part of evaporation. If water gets evaporate then ultimately bond formation will become poor and as time passes, material will fail to carry load and starts deterioration of binding material. In such case, particles gets separate and above brick layer settled down and ultimately displace the entire layers above that weak point.
Second most obvious reason is vibration. Sources of vibrations are natural disasters like earth quake, some road construction nears your property premises, installed heavy duty equipment at your home without vibration absorber pads and sometime nail you are fixing with wrong tool.
Third most obvious reason of cracks is atmospheric conditions. Some materials lack properties that able to survive in winter as well as in summers. So what happen is that some materials gets shrink in winter and expand in summers.
Sometimes the door or window frames not properly fixed and available room for free movement. In such case, every time door you closed the door have a direct impact on the door jamb. This also propagate cracks in walls.
Whatever the reason, if cracks appear, you only left with option of repairing it. In order to repair the cracks, first detail inspection is required around doors, windows, moldings and corners.
First address the root cause by fixing hairline cracks that may get larger with time. Repairs to settlement cracks will not need further attention.
Vibration cracks are generally small and will probably require periodic repair. Cracks caused by atmospheric conditions may be prevented by controlling temperature. Cracks due to faulty construction usually will not recur if the cause is eliminated.
What you need for repairing Cracks:-
- Blade for widening of cracks.
- Patching material generally putty
- Painting brush
- Paint scrapper
- Flexible putty knife for filling
- Fine grade sandpaper