SOURCES OF DAMPNESS

Dampness in buildings is generally due to one or more of the following reasons:

1. Faulty design of structure
2. Faulty construction or poor workmanship
3. Use of poor materials in construction

These causes give rise to an easy access to moisture to enter the building from different points, such as rising of moisture from the ground and rain penetration through walls, roofs and floors. The moisture entering the building from the foundation and roofs travels in different directions further under the effects of capillary action and gravity, respectively. The entry of water and its movements, in different parts of the building, are positively due to one or more of the causes listed above. The various sources that create dampness in buildings are as follows.

23.1.1 Rising of moisture from the ground

The sub-soil or ground on which the building is constructed may be made of soil that easily gives access to water to create dampness in buildings, through the foundations. Generally, foundation dampness is caused when the building structures are constructed on low-lying waterlogged areas, where a sub-soil of clay or peat is commonly found, through which dampness would easily rise under capillary action unless properly treated. This dampness further finds its way to the floors, walls, etc. through the plinth.

23.1.2 Action of rainwater

Whenever the faces of walls are not suitably protected from the exposure to heavy showers of rains, they become the sources of dampness in a structure. Similarly, the poor mortar joints in walls and cracked roofs also allow dampness to enter a building structure. Sometimes, due to faulty eave board the rainwater may percolate through roof coverings.

23.1.3 Rain penetration from tops of walls

All parapet walls and compound walls of buildings, which have not been protected from rain penetration by using damp-proof course or by such measures on their exposed tops, are subjected to dampness. This dampness in buildings is of serious nature and may result in unhealthy living conditions or even in structurally unsafe conditions.

23.1.4 Condensation due to atmospheric moisture

Whenever the warm air in the atmosphere is cooled, it gives rise to the process of condensation. On account of the condensation, the moisture is deposited on the whole area of walls, floors and ceilings. However, this source of dampness is prevalent only in certain places in India, where very cold climates exist.

23.1.5 Miscellaneous sources or causes

The various other sources or causes, which may be responsible for dampness in buildings, are mentioned below:

1. Poor drainage of the site: The structure if located on low-lying sites causes waterlogged conditions when impervious soil is present underneath the foundations. Therefore, such structures that are not well drained cause dampness in buildings through the foundation.
2. Imperfect orientation: Whenever the orientation of the building is not proper or geographical conditions are such that the walls of the building get less of direct sunrays and more of heavy showers of rain, then such walls become liable to dampness.
3. Constructional dampness: If more water has been introduced during construction or due to poor workmanship, the walls are observed to remain in a damp condition for sufficient time.
4. Dampness due to defective construction: The dampness in buildings is also caused due to poor workmanship or methods of construction, namely inadequate roof slopes, defective rainwater pipe connections, defective joints in the roofs, improper connections of walls, etc.