Damp does not discriminate. It can reveal itself in the largest mansions as well as in the smallest appartments. Here we will uncover the most common origins in the hope that the information may help you to eliminate options and move to a solution.
The usual suspects:
3. Buried leak outside
4. Buried leak inside
5. Bathroom waterproofing
1. RAIN WATER INFILTRATION
Rain water infiltration is often the source of damp in the house. Proper rain water management is crucial so that water can flow away from the house. This is a big deal yet commonly overlooked.
Rain water related damp is usually found on the inside of exterior facing walls. Water likes to get in through broken tiles on the roof, cracks in the wall, porous walls, badly fitted window frames, terrace drains etc.
The same as rain, if daily irrigation is set up that it wets the wall of the house daily, it can also lead to damp. This then would only appear in the summer months. This type of damp usually disappear in the summer months and come back in the winter. If it is in the summer, this indicates that there could be a problem on the irrigation set up.
3. WATER SUPPLY LEAKS
A leak on a water supply inside the house can quickly cause wide spread water damage. Even slow hidden drip-drip leaks can do quite some damage. 1 Drip a second equals approximately 35 litres in 24 hours!
That is 200 liters of water that has to go somewhere in one week.
Exterior leaks in underground pipes such as the mains can also cause damp in the house if it is close to the house walls.
If you are not sure whether there are house leaks, a simple way to check is to look at the water meter reading. The watermeter is usually situated just outside the house at the main entrance. In apartements, it is usually in a cupboard in the communal area not far from the front door.
First make sure all taps are properly closed, inside and in the garden. Without using any water, check the reading and then again in an hour. If there is a difference, there is water leaking somewhere.
Here is a picture of a typical water meter in France. The last three digits in red represent liters and the black number represent cubic meters. For example if there was a leak of 100 liters an hour, the reading on the red numbers would be ‘418’ after one hour.
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.
5. AIR CONDITIONING UNITS
In the summer these units ‘leaks’ naturally a remarkable amount of water which is basically condensation. If the drain pipe of the unit is broken or in the wrong place, that can lead to damp walls.
The formation of mould is not always related too damp. More often than not it is simply poor ventilation in the house. Normal activity in the house creates quite a bit of humidity such as cooking, washing, showers, baths…even breathing. If there is poor ventilation, this high humidity will condensate on cooler areas especially at night.
This continuous condensation eventually turn into mould. To give an example of a house where therer were never any problems. Insulation was installed in the roof and double glazed windows fitted to save on energy. This was good but suddenly the natural damp in the house had nowhere to go and soon the mould appeared. The house was too airtight. A mechanical ventilation system was installed that ‘balanced’ the conditions in the house.
Mould will also form in areas that are already damp but no ventilation. So it is clear that mould is present where there is poor ventilation.