Dampness

Dampness

Structure building, either the results of intrusion from outside or condensation from the structure. A high proportion of dampness problems in buildings are caused by ambient climate-dependent factors of condensation and rain penetration.

CAPILLARY PENETRATION- Of fluid from rock bottom-up through concrete or masonry is known as “rising dampness” and is governed by the shape and porosity of the event materials through which this evaporation limited capillary penetration takes place.

STRUCTURAL DAMPNESS- No matter the mechanisms through which it takes place, is exacerbated by higher levels of humidity. Structural dampness is the presence of unwanted moisture within the structure.

 

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CAUSES OF DAMPNESS

Dampness could also be caused by:

1.   Spring Water

2.   Rainwater And

3.   Leakage from Pipe

1. Dampness thanks to Ground Water:

All buildings are founded on soils. Soil holds water for a long time. Sometimes water level may rise and are available in touch with foundation. Thanks to capillarity moisture from the ground rise into the foundation, floor and even in wall.

2.   Rainwater:

·         From wall top: If top of wall isn’t protected with an impervious course like concrete, water can enter the wall and keep it damp for an extended time.

·         From face of external walls: Splashing of outer wall by rain results into moisture entering the wall. Poor plaster coat is the main source of this sort of dampness.

·         Improper fixing of down take pipes:If down take pipes from roof aren’t properly fixed, a skinny layer of water stagnates near the mouth of down take pipes. This results in entry of rain water into roof and wall.

·         Improper slopes to the roof: In flat roofs, repeatedly this is often the cause for the dampness of roofs. If slope isn’t given properly, water ponds are formed on the flat roof, which ends up into entry of water into slab. Once water enters the slab it remains for while creating dampness.

·         Defective construction: Imperfect wall joints, improper slopes to chaja, construction joints in roof etc. cause dampness in buildings.

3. Leakage from Pipes:

From overhead tanks, pipes are appropriated roof and along the wall. From bathrooms, toilets and kitchen water is drained out with different types of pipes. The pipes are joined to urge required length and turns. Repeatedly water leaks through joints resulting into moisture in building components.

 

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ILL-EFFECTS OF DAMPNESS

Ill-effects of dampness are as listed below:

  •  Patches develop and destroy the looks of the building.
  • Colour wash, white wash and paintings are damaged.
  • Plaster crumbles.
  • Bricks and stones disintegrate endangering the building.
  • Steel within the slabs and beam start rusting, it reduces the lifetime of structure.
  • Electric short circuits may takes place.
  • Flooring may settle.
  • Floor covers are damaged.
  • Wooden components of buildings like door frames and cupboard warp.
  • Dry rotting of wood takes place.
  • Termite becomes active and attack wooden articles.
  • Mosquito breeding takes place.
  • Darkness alongside warmth and darkness breed germs giving rise to several diseases.

 

REQUIREMENTS OF a perfect MATERIAL FOR DAMP PROOFING

·         The requirements of perfect materials for damp proofing are:

·         It should be impervious.

·         It should be flexible.

·         It should be easy to hold out leak proofing joints.

·         It should be stable.

·         It should be durable. Its life should be the maximum amount because of the lifetime of building itself.

·         It should resist the load safely.

·         It shouldn’t contain sulphates, chloride and nitrates.

·         It should be cheap.

 

MATERIALS FOR DAMP PROOFING

The materials used for damp proofing are:

·         Bitumen: In hot condition, it’s highly flexible and may be applied with brush to the bedding of concrete or mortar. Thickness of coat provided is about 3 mm.

·         Mastic asphalt: it’s a semi-rigid material. It’s obtained by heating asphalt with sand and mineral fillers. It’s perfectly impervious. It should be laid very carefully.

·         Bituminous or asphaltic felt:it’s a versatile material which is out there in rolls. It’s provided on roof slabs and parapet walls with an overlap of 100 mm on sides. The laps are sealed with bitumen. They are doing not withstand heavy movements.

·         Bricks: Good bricks with water absorption but 5 per cent are sometimes wont to make damp proof courses. The bricks are laid in two to four courses in cement mortar.

·         Stones:Stones like granite trap and slates could also be laid over wall to its full width as dampness course.

·         Mortar: Cement mortar of proportion 1:3 with small quantity of lime and waterproofing agents are wont to make a waterproofing course to foundations, ground floor slabs, top of parapet walls etc. it’s going to be used for plastering external walls.

·         Concrete: to see the increase of water into walls a course of 75 mm to 100 mm cement concrete 1:1×1/2 : 3 or 1:2:4 is provided before starting constructing walls. These courses could also be given hot bitumen paint as a further precaution.

·         Metal sheets: Aluminium, copper or lead sheets are provided to seal the development joints. Over these sheets, bituminous seal is provided.

·         Plastic sheets: Plastic sheets are an excellent course for damp proofing. They’re made from black polythene of thickness 1 mm.

 

METHODS OF DAMP PROOFING

Various methods of damp proofing are as given below:

  1. Providing D.P.C. course
  2. Providing cavity walls
  3. Surface treatment
  4. Integral treatment
  5. Guniting and
  6. Pressure grouting. 

1. Providing damp proof course DPC: It consists of providing a humid proof course between the source of dampness and building component. The DPC could also be with any water repellent material like bitumen, mastic asphalt, and cement concrete, metal or plastic sheets.

DPC should cover full width of wall. It should be laid on levelled surface of mortar. Joints should be minimum and will not be at critical points. When horizontal DPC on roof is sustained on vertical face of parapet wall, the junction should be crammed with about 75 mm fillet of cement concrete.

2. Providing cavity wall: wall could also be constructed to guard foundation masonry and therefore the wall the cavity prevents moisture travelling from outer to inner wall.

3. Surface treatment: If moisture is merely superficial and not struggling this method is beneficial. It consists of application of layer of water repellent compounds on the surface. a number of the waterproofing agents used for such treatment are silicates of sodium or potassium and sulphates of aluminium, zinc and magnesium.

4. Integral treatment: It consists of mixing commercially available compounds in water before concrete is wet mixed. These compounds are made up of chalk, talc, flutter earth or chemical compounds like salt, aluminium sulphate, salt etc. Some compounds contain compounds like soap, petroleum oils, fatty acids etc.

5. Guniting: during this method, a mix of cement and water is forced by cement gun on the surface to be made waterproof. Later 1:3 or 1:4 cement mortar is applied to the surface with pressure using compressed gas. Thus an impervious layer of mortar is provided.

6. Pressure grouting: this is often the tactic wont to seal cracks within the concrete surfaces. During this method, cement grout is forced struggling.

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