What is Dampness?
Dampness in any building occurred by absorption of water by the materials. If dampness occurred in the building, it becomes harmful to person those are living in the building.
Damp Proof Course(DPC) – A course is provided in the building to prevent the entry of the damp into the building, this course is known as the damp proof course(DPC). This treatment is given to the building at the time of their construction.
Causes of Dampness
There are various causes that are responsible for the entry of dampness into the building.
- Ground Water Table – If the groundwater table is high, it will affect the foundation, because the building material used for foundation absorbs the water from the ground by capillary action.
- Rain – If the external walls of the building are not protected then rainwater may affect the building.
- If the building is located in the area which cannot be easily drained off, dampness will affect the building.
- It may occur due to bad workmanship in construction.
- The newly constructed walls remain damp for a short period.
- The very flat slope of a roof may also lead to the penetration of rainwater which is temporarily stored on the roof.
- The parapet walls and compound walls should be provided with a damp proofing course on their exposed tops. Otherwise, the dampness entering through these exposed tops of such wall may lead to a serious result.
Effects of Dampness
- There are various effects of dampness are as follows:
- The plaster will be softened and may crumble.
- Electric fitting may affect.
- Distempers or paints may damage.
- Unhealthy conditions for occupants.
- Growth of termites.
- The steel used in building construction may be corroded.
- Rise to the breeding of mosquitoes.
- Unattractive patches are formed on the wall surface and ceiling.
- The material used as floor covering is seriously damaged.
- The continuous presence of moisture in the walls may cause efflorescence which may result in disintegration of stone, bricks, tiles etc.
Damp Proofing Material
There are various materials that are used for damp proofing.
- Hot Bitumen– It is a flexible material which is placed on concrete or mortar.
- Mastic Asphalt – It is a semi-rigid material. It provides an impervious layer for damp proofing.
- Bituminous Felts – It is a flexible material which is available in rollers of walls width. It is easy to lay and laid upon cement mortar.
- Metal Sheets – The sheets of copper lead and aluminium are used as a damp proof course.
- Stone – If stones such as granites, slates etc. laid in cement mortar they work as a damp proof course.
- Cement Concrete – Cement concrete with a ratio of 1:2:4 is a good damp proof course. It is generally provided in the building at the plinth level.
- Plastic Sheets – Plastic sheets are a very good course for damp proofing. They are made up of black polythene having a thickness up to 1 mm.
Methods of Damp Proofing
There are various techniques for protection of defect of dampness are as follows:
Use of Damp Proof Course
The damp proof course is the layer of materials like bituminous, cement, stones etc. They are provided in the building at all location at suitable places from where water may enter into the building. Generally, it is provided in the building at plinth level for walls, above the concrete bed for flooring.
In this method, a thin film of water repellent material is provided over the surface which fills the pores of the materials of the building which are exposed to the moisture.
Integral Damp Proofing Treatment
In this method, water repelled compounds are mixed to the concrete or mortar during the process of mixing concrete. These compounds act as barriers to moisture to enter into the building.
Cavity Wall or Hollow Wall
It consists of cavity or air drains into the wall to prevent the rising of moisture from the ground to the wall. To know more about cavity wall see What Is Cavity Wall? Purpose & Constructional Details.
Pressure Grouting or Cementation
In this technique, holes are drilled at the different part of the building at selected points. Then cement paste of thin consistency is immersed into the holes by pressure. This makes the structure water-tight.
I hope now you have an idea about dampness and how can you protect your home from it.
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