What is cause of moisture in brick/block masonry walls almost?

Moisture problems in exterior masonry walls can be caused by either water leakage or air infiltration-condensation, or a combination of both. However, because many symptoms of water leakage and air infiltration-condensation are similar, it's vital to investigate both, even when the problem seems to clearly indicate one or the other. A pronounced symptom of one may be overshadowing a symptom of another. For a balanced investigation of an exterior masonry wall system's moisture problem, you should:

• Review the wall construction and the mechanical system
• Survey the interior conditions
• Conduct water leakage tests
• Measure actual pressures within rooms
• Do infrared analysis to determine the mechanism of moisture migration within a wall system
• Analyze and test a mock-up

Besides possibile leaks from the atmosphere and/or installations, the warm and humid air inside the buidlings penetrates into cold masonry and this causes condensation of humidity and therefore moisture

Leaking water lines either in walls or floor

BECAUSE OF DAMPING BY LEAKAGE AND IN WINTER MOISTURE IS ALSO A MAJOR CAUSE.

IT SHOULD BE BECAUSE OF TEMPERATURE VARIANCE BETWEEN INDOOR AND OUDOOR CONDITIONS, SIMPLY WE CAN CALLED AS CONDENSATION