Damp Walls: Some Causes and Solutions

Usually a damp wall is noticed after already too late. When the paint has begun to peel off the wall and overgrown with moss, then we realized that the wall is damp or wet . Damp wall can cause health problems.

Some causes of damp wall:

Rainwater
Rainwater leaks from porous cement duct. It is easy to find the cause, as the wall is only damp when rainy season. The water may not directly go down to the floor, but absorbed in porous wall. Cement plaster and sealant can help to avoid leaking porous duct.

Roof with concrete duct as shown in the above drawing, usually it is built in a tight space. Sometime the wall is directly adjacent to neighbors yard, and no part of the roof is covering top of the wall to avoid rainwater goes into neighbor yard.

Concrete duct of the above design collects rainwater from the roof. But sometime that concrete duct is cracked and allow water to seep into wall. Sometime we cannot find any water droplets on the floor, but the rainwater is absorbed by the wall, and creating high humidity air inside the room.

If needed, remove some old plaster around cracked duct, as it is a clue that the old cement mixture has too much sand. Re plaster using better mixture, 1 part of cement with 3 parts of sand, if needed use minimum sand or more cement to cover the crack. Then put waterproofing coating onto duct.

Water line leaks

Water leaks can occur in water pipes from the pump, from the tank or reservoir, or from municipal water supply network. Water supply pipe must not be covered by cement, because it would become complicated to repair if leaking. Water supply pipe leaks not only waste the water. Leaking pipe can also contaminate the water in it. In some countries, tap water is drinkable, no need to boil it. Because tap water quality standards in that country must be as good as drinking water, not only for washing and cleaning standard. This is where the role of expert plumber needed to apply simple yet functional pipeline and easy to repair if damaged, and ensure nothing dirt enter.

For reasons of beauty, often clean water pipe is installed hidden in the wall. Hidden water pipes will be difficult and costly to fix as we need to open the wall, especially if the walls are covered with tiles like in bathroom and kitchen wall. Sometime the easiest and cheapest way to fix leaking pipe is by closing the leaking old pipe and replace it with a new pipe with different pipe path.

Sewer leaks

Cement sewer line (concrete duct) is not watertight and water will seep into the walls. It is not very easy to put sealant on to duct surface as many dirt deposit. The most effective solution is to replace the concrete duct with PVC pipe.

Source of water vapor in the room
A cement bathtub without ceramic can cause water to seep into the wall. Keep in mind that the pores on the wall will cause a capillary phenomena that sucks water into the wall. Water in the wall then vaporizes and causing high humidity air in the room.

Capillary phenomena occur in plants that pump water from the soil to leaves. Capillary action is usually applied to the stove wick, to pump oil from the stove tank up.

The existence of water source in the soil

Water from moist soil can rise to the wall because of the capillary phenomena. Some home designs put flower pot of concrete side by side with the walls of the house. Water from inside the flower pot can seep into the wall. Because of capillary force, water spreads inside the wall and causes moist wall.

The height of the water sucked by the wall capillary force can reach several meters. In plants, water is pumped by capillary force can even reach the height of tens of meters. That is the distance from roots to leaves on the highest branches. Capillary sucks water continuously without rest. It will stop sucking water only when the wall is saturated by water. If the water in the pores of the wall evaporates, the capillary force will replenish the empty pores with water from the ground, and so on endlessly.

Walls that are always damp due to capillary phenomena often confuse the inhabitants of the house, because there is no leak from the roof. Whereas the water source is from below. In a long time the residents of the house can be sick due to the high humidity air in the room. Then this phenomenon sometime is connected with the unseen or mystical thing, because they cant find a logical explanation.

On sloping land, some houses are built with part of wall covered by soil, because the foundation is built on a lower part of land lot. There are also homeowners who intentionally pile up the soil behind wall to make a higher ground, for example: to create a multi-storey yard, elevate the floor behind a wall, or because no place to throw away the debris and excess soil.

Actually the height of the soil should not exceed the height of the foundation. If the height of the soil exceeds the height of the foundation. Then the weight of the soil will push the wall from the side, and the water it contains will moisten the wall.

The piles of soil are not like stacked bricks, arranged perpendicular from bottom to top. The soil pile has the same properties as the pile of sand, which will form like a mountain, wider at the bottom. The soil at the bottom will move sideways as a result of being pressed by the weight of the soil above it. The pressure of the soil piled up behind the wall can knock the wall down.

If you have to raise the soil above the foundation, plaster of the exposed wall should be strengthened by reducing the sand mixture. If necessary use cement without sand, to reduce wall pores to prevent capillary phenomena. Sometime it is necessary to add more brick layers to make the wall stronger to withstand water seepage and sideways pressure by the mound.