Damp is a real problem. It can have various origins and all suspects should be considered.
The usual suspects:
3. Leak outside
4. Leak inside
5. Bathroom waterproofing
1. RAIN WATER INFILTRATION
Rain water infiltration is often the source of damp in the house. Rain water management should be in place so that water can flow away from the house. This is the main idea. But often there are no gutter or no proper slope. Water goes into the ground directly next to a wall and depending on the construction methods water transfer through the wall. This type of damp usually disappear in the summer months and come back in the winter.
Another common place of infiltration is cracks in the wall even hairline cracks.
Rain water infiltration leaks are usually found on the interior of exterior facing walls
The same as rain, if daily irrigation is set up to close to the house, it can also leads to damp. This then would only appear in the summer months.
A leak on a water supply inside the house can quickly cause wide spread water damage. Even slow drip drip leaks. 1 Drip a second equals 35 litres in 24 hours! That is 200 liters of water that has to go somewhere after a week.
Exterior leaks in underground pipes such as the mains can also cause damp in the house if it is close the house walls.
How do I test my water supply for possible leaks?
4. BATHROOM WATERPROOFING
The silicone seal around a bath or a broken seal in the shower is a very common cause of damp in the house. They are usually on walls close to the shower or in the rooms that is adjecent to a bathroom.