What Is Dampness ?
Dampness is a property of a building when the water or moisture is absorbed by the building material. Dampness is a very harmful effect, by this a building can also collapse because the load-carrying of the material is getting reduced.
In a damp house, it is very danger for living a person. To overcome this effect civil engineers apply for a course over the plinth level, this course is called Damp Proof Course (DPC). Damp Proof Course is applied when the construction is ongoing.
Causes of Dampness
There are naturally various causes are responsible for the dampness. Those causes are the following-
- Ground Water Table: If the groundwater table is high then it will affect the foundation of the building because the materials which are used in the foundation construction absorbed water from the groundwater table by capillary action. It also happens when the groundwater tale is rise due to heavy rain or other natural effects.
- Rain: The external walls of the building is not protected properly then the rainwater can damage the walls and dampness will occur.
- In some places drainage water is not drained off from the building properly, then it may affect the foundation of the building.
- The dampness can be occurred due to bad materials used and bad workmanship.
- Sometimes in new constructed walls dampness occurred because of a lack of water absorption of water.
- If the roof of the building is too much flat then the rainwater could not pass properly and is stored in the roof, that’s why dampness happens.
- You should need to provide a damp-proof coating on the top surface of the parapet wall. If we don’t do this and dampness may occur then it will create a huge disturbance in our building.
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Effects of Dampness
There are many different effects of dampness, those are-
- The main effect of dampness is the plaster becomes soft than the previous one and crumbles in nature.
- The another effect of dampness is the paints and distempers are getting damaged.
- Electric wiring of that building may damaged by the dampness effect.
- Dampness will create an unhealthy condition and atmosphere for the occupants.
- The another major effect of the dampness is the steel reinforcements of the RCC structure is getting corroded, for this the whole load carrying capacity of the building will reduce.
- Dampness will allow various type of insects, fungus and termites.
- It will help the breeding of mosquitoes and their existence.
- The floor material like marble, floor tiles, etc are getting damaged by the dampness.
- Many watery patches are occurred in the walls and ceilings, sometimes plaster becomes bulky in nature.
- By the dampness effect there is always present of moisture content which may cause the efflorescence effect, which is very harmful for any building.
Damp Proofing Material
There are various damp proofing materials are available in the market which are used for the damp proofing, those are-
- Hot Bitumen: Hot bitumen is a flexible material which is used as damp proofing material, it is mainly used on the top surface of concrete or mortar.
- Bituminous Felts: Bituminous felts are also a flexible material which is available in the rollers of the walls width. This material is laid on the cement material and easy to laid down.
- Mastic Asphalt: This is another damp proofing material which is semi-rigid in nature and it creates an impervious layer on the surface.
- Metal Sheets: Metal sheets are mainly made of aluminum or copper which is used as a damp-proof material.
- Stone: Stones are also act as a damp proofing material. Granite, slate, etc which is laid on the cement concrete and resist the dampness effect.
- Cement Concrete: Cement concrete is also a good damp-proof material which is provided in the plinth level, in damp proofing 1:2:4 mix ratio of concrete is used.
- Plastic Sheets: Plastic sheets are generally made with black polythene which is 1mm thickness, it is very effective damp proofing material, easy to use and cheap.
Methods of Damp Proofing
There are various methods and techniques are used for damp proofing, those methods are-
1. Membrane Damp Proofing:
In this method a damp proofing course is applied between the damp part and the building component. Bitumen, mastic asphalt, plastic sheets are mainly used. Damp proofing are mainly provided horizontally but sometimes it can be provided in vertically also.
The general principles are followed-
- Damp proof course must cover the full thickness of the walls.
- The supporting mortar bed of damp proof course must be levelled, even projection free, this is done because of it should not getting damaged.
- In the wall corners or junctions, the damp proof curse must be provided in continuous layer.
- We need to checkout the wall or floor surface otherwise it may affect the finishing work of that particular portion.
2. Integral Damp Proofing:
By this type of damp proofing method, some materials are mixed with the concrete mix and that material creates an impervious layer and it helps to resist the dampness. Generally, one kg of waterproofing material is mixed with one bag of cement.
3. Surface Treatment:
In this technique, we use water repellent materials are used. Wall plasters with a ratio of 1:1:6 are used for preventing dampness.