Dampness in BuildingsDampness in BuildingsCauses of Dampness in Causes of Dampness in

BuildingsBuildingsRemedial measuresRemedial measures

BY : Ashar GillBY : Ashar Gill

TopicsTopics• DefinitionsDefinitions• Types of DampnessTypes of Dampness• Causes of DampnessCauses of Dampness•Effects of Dampness• Remidial measuresRemidial measures• Classification of Damp proofing Classification of Damp proofing

materialmaterial

DefinitionsDefinitions• DampnessDampness

– The excess entry or penetration of moisture inside a The excess entry or penetration of moisture inside a building through its building through its

– FloorsFloors– Walls andWalls and– Roofs Roofs is called Dampness.is called Dampness.Dampness is dangerous both forDampness is dangerous both for

InmatesInmatesBuildingBuilding

• Due to dampness the building become unhygienic.Due to dampness the building become unhygienic.• Dampness in buildings is a risk factor for health effects.

DefinitionsDefinitions• Peeling offPeeling off

– This term is related to plaster and it means This term is related to plaster and it means that the plaster surface get disfigured.that the plaster surface get disfigured.

• Blistered and Bleached– These term are related to PaintingThese term are related to Painting

• DPC (Damp proof course) (Damp proof course)– It is a continuous layer of impervious material It is a continuous layer of impervious material

between source of dampness and building between source of dampness and building componentcomponent

Types of DampnessTypes of Dampness• Based on the movement of

moisture the dampness can be of the following three types.

1. Rising or capillary dampness.2. Falling or penetrating dampness.3. Condensation dampness.

Causes of DampnessCauses of Dampness

• Following are the main causes of Following are the main causes of dampness in a buildingdampness in a building

1.1. Rain penetrationRain penetration2.2. Level of siteLevel of site3.3. Drainability of the SoilDrainability of the Soil4.4. Climatic conditionsClimatic conditions5.5. Defective OrientationDefective Orientation6.6. Entraped moisture in the buildingEntraped moisture in the building7.7. Defective construction materialDefective construction material8.8. Defective construstionDefective construstion9.9. Moisture originates in the building.Moisture originates in the building.

Causes of DampnessCauses of Dampness1.1. Rain penetrationRain penetration

• It is the main source of dampness. Heavy rain of short It is the main source of dampness. Heavy rain of short duration is less dangerous. rain water enters through duration is less dangerous. rain water enters through joints, cracks and porous bricks or stones.joints, cracks and porous bricks or stones.

2.2. Level of siteLevel of site• Low laying building sites are effected by the Low laying building sites are effected by the

depositing surface water and underground water.depositing surface water and underground water.3.3. Drainability of the SoilDrainability of the Soil

• Course grained soils like Sandy or gravely soils Course grained soils like Sandy or gravely soils provides good drainibility conditions and fine grained provides good drainibility conditions and fine grained soils like clay retain water and cause dampness.soils like clay retain water and cause dampness.

Causes of DampnessCauses of Dampness4.4. Climatic conditionsClimatic conditions

• In cold climatic condition dampness causes In cold climatic condition dampness causes due to condensation of water vapors.due to condensation of water vapors.

5.5. Defective OrientationDefective Orientation• If building is exposed to direct rain showers If building is exposed to direct rain showers

and less sun rays then it cause dampness. and less sun rays then it cause dampness. 6.6. Entrapped moisture in the buildingEntrapped moisture in the building

1.1. Due Over soaked bricks and use of salty or Due Over soaked bricks and use of salty or alkaline water results dampness in building. alkaline water results dampness in building.

Causes of DampnessCauses of Dampness7.7. Defective construction materialDefective construction material

• Porous bricks, soft stones, alkaline water Porous bricks, soft stones, alkaline water etc. cause dampness of building.etc. cause dampness of building.

8.8. Defective constructionDefective construction• Through defective joints of parapet, Through defective joints of parapet,

copping and masonry joints moisture can copping and masonry joints moisture can enter in the building.enter in the building.

9.9. Moisture originates in the building.Moisture originates in the building.• It is due to the leakage through water It is due to the leakage through water

supply or sanitary system of building.supply or sanitary system of building.

Effects of DampnessEffects of Dampness• Following are the harmful effects of dampness in Following are the harmful effects of dampness in

buildings.buildings.– Building become esthetically poor.Building become esthetically poor.– It cause It cause dry Rotdry Rot to the wooden members provided in to the wooden members provided in

the building.the building.– It cause corrosion of metals used in building.It cause corrosion of metals used in building.– Plaster peels off.Plaster peels off.– Paint blistered and bleached and the surface disfigured.Paint blistered and bleached and the surface disfigured.– Holes and pits are formed in topping of floors.Holes and pits are formed in topping of floors.– Efflorescence occurs and bricks disintegrate and turn in Efflorescence occurs and bricks disintegrate and turn in

to powder.to powder.– Un hygienic conditions in building.Un hygienic conditions in building.

Remedial MeasuresRemedial Measures• By Damp Proofing Courses (DPC)By Damp Proofing Courses (DPC)• By surface treatmentBy surface treatment• By water proofing constructionBy water proofing construction• By special devices/techniquesBy special devices/techniques

ByByDamp Proofing Damp Proofing

CoursesCoursesDPCDPC

Damp proofing materialDamp proofing material• Classification of Damp proofing Classification of Damp proofing

materialmaterial• Qualities of a good Damp proofing Qualities of a good Damp proofing

MaterialMaterial• Important places for Damp proofing Important places for Damp proofing

materials.materials.

Classification of Damp proofing Classification of Damp proofing materialmaterial

• Flexible MaterialsFlexible Materials• Material which do not crack and Material which do not crack and

deform due to loadings.deform due to loadings.– Bitumen Mastic (Mastic Asphalt)Bitumen Mastic (Mastic Asphalt)– Bitumen feltBitumen felt– Hot BitumenHot Bitumen– Metal SheetsMetal Sheets

• Rigid MaterialsRigid Materials• Materials that cannot resist Materials that cannot resist

transverse stresses.transverse stresses.– Rich ConcreteRich Concrete– MortarMortar– BricksBricks– Stone SlabsStone Slabs

Flexible MaterialsFlexible Materials– Bitumen Mastic (Mastic Asphalt)Bitumen Mastic (Mastic Asphalt)

• Hot Bitumen or Asphalt + SandHot Bitumen or Asphalt + Sand• Applied in hot state in 1” to 2” (2 cm to 5 cm)Applied in hot state in 1” to 2” (2 cm to 5 cm)

– Bitumen feltBitumen felt• 6 mm thick bitumen sheet available in roll form 6 mm thick bitumen sheet available in roll form

– Hot BitumenHot Bitumen• It is sprayed at @ 1.75 kg/mIt is sprayed at @ 1.75 kg/m22

– Metal SheetsMetal Sheets– Lead, copper, Aluminum sheets can be usedLead, copper, Aluminum sheets can be used

• Lead can react chemically with cement so should be Lead can react chemically with cement so should be laid in lime mortar.laid in lime mortar.

• Minimum thickness of copper sheets should be 3 mm Minimum thickness of copper sheets should be 3 mm ..

Rigid MaterialsRigid Materials– Rich ConcreteRich Concrete

• 1” to 2-1/2” thick layer of P.C.C (1:2:4) painted with hot 1” to 2-1/2” thick layer of P.C.C (1:2:4) painted with hot bitumen is appliedbitumen is applied

– MortarMortar• Rich or fat cement mortar CS(!:3) is laid in ¾” thickness Rich or fat cement mortar CS(!:3) is laid in ¾” thickness

(2 cm) as vertical DPC.(2 cm) as vertical DPC.• Painted with bitumenPainted with bitumen

– BricksBricks• Over burnt bricks are used in two layers in CS(1:3) mortarOver burnt bricks are used in two layers in CS(1:3) mortar

– Stone SlabsStone Slabs• Two layers of stone slabs in lime cement and sand mortar Two layers of stone slabs in lime cement and sand mortar

(1:1:6) is provided in areas where stone is easily available.(1:1:6) is provided in areas where stone is easily available.

Qualities of a good Damp Qualities of a good Damp proofing Materialproofing Material1.1. ImperviousImpervious2.2. DurableDurable3.3. Non disintegratableNon disintegratable4.4. Stable under the loadingStable under the loading5.5. Level finishLevel finish6.6. Full coverage of wall thicknessFull coverage of wall thickness7.7. AvailabilityAvailability8.8. EconomicalEconomical

Important places for Damp Important places for Damp proofing materialsproofing materials• At Plinth Level (in walls ) (external & At Plinth Level (in walls ) (external &

Internal)Internal)• Parapet wallsParapet walls• Window sillWindow sill• Basements and Under ground FloorsBasements and Under ground Floors

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Dampness in buildings is a Dampness in buildings is a risk factor for health effectsrisk factor for health effects

Associations found with cough, asthma, Associations found with cough, asthma, tiredness, airway infection tiredness, airway infection – Increased relative risk 1.4-2.2Increased relative risk 1.4-2.2

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Ozone-generating OOzone-generating O33 “Air Purifiers” “Air Purifiers”

• Portable electronic appliances Portable electronic appliances • Release ozone gas Release ozone gas by designby design or or as a as a

by-productby-product (“ozone generators” (“ozone generators” versus ionizers & electrostatic versus ionizers & electrostatic precipitators)precipitators)– Ozone generators 300 - 400 ppbOzone generators 300 - 400 ppb– Personal air purifiers ~ 100 ppbPersonal air purifiers ~ 100 ppb

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What is condensation?What is condensation? Condensation is the formation of liquid drops from Condensation is the formation of liquid drops from

water vapor.water vapor.

More DetailsMore Details It is the process which creates clouds, and so is It is the process which creates clouds, and so is necessary for rain and snow formation as well. necessary for rain and snow formation as well. Condensation usually occurs when a parcel of rising Condensation usually occurs when a parcel of rising air expands and cools. If it cools enough, some of the air expands and cools. If it cools enough, some of the water vapor molecules clump together faster than water vapor molecules clump together faster than they are torn apart from their thermal energy. A very they are torn apart from their thermal energy. A very important part of this process is the release of the important part of this process is the release of the latent heat of condensation. This is the heat that latent heat of condensation. This is the heat that was absorbed when the water was originally was absorbed when the water was originally evaporated from the surface of the Earth. The heat evaporated from the surface of the Earth. The heat removed from the surface through evaporation is removed from the surface through evaporation is released again up in the atmosphere when clouds released again up in the atmosphere when clouds form. This process keeps the Earth's climate cooler form. This process keeps the Earth's climate cooler that it would otherwise be if there were no water. that it would otherwise be if there were no water. Another way in which condensation occurs is during Another way in which condensation occurs is during the formation of dews.the formation of dews.

Typical section of WallTypical section of Wall

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DPC at different locationsDPC at different locations

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1- At Plinth Level

2- At Parapet Walls

3- At Window Sills

4- Basements & Under Ground Floors

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Difference of Bitumen and Difference of Bitumen and AsphaltAsphalt• Bitumen can be found in Nature.Bitumen can be found in Nature.• Asphalt is a manufactured product, Asphalt is a manufactured product,

produced by refining crude oil by produced by refining crude oil by heating at 300 heating at 300 ooC in a distillation C in a distillation column.column.

• Naphthene base crude oils are Naphthene base crude oils are suitable suitable

Naphthene base crude oilsNaphthene base crude oils• Crude oil containing asphaltic Crude oil containing asphaltic

materials but very little or no paraffin materials but very little or no paraffin wax. This type of oil is suitable for wax. This type of oil is suitable for making gasoline, lubricating oil and making gasoline, lubricating oil and asphalt. It is also called asphalt-base asphalt. It is also called asphalt-base crude.crude.

Practical Advice for Practical Advice for Reducing Excessive Moisture*Reducing Excessive Moisture*• Fix roof and plumbing leaks right awayFix roof and plumbing leaks right away

• Check for standing water Check for standing water (e.g., basement & refrig drip pan)(e.g., basement & refrig drip pan)

• Make sure rain drains away from house (& irrigation) Make sure rain drains away from house (& irrigation)

• Vent clothes dryer to the outsideVent clothes dryer to the outside

• Ensure adequate ventilation (from outside) and Ensure adequate ventilation (from outside) and circulation (inside). Use fans that vent air to the outside circulation (inside). Use fans that vent air to the outside when bathing, showering, and cookingwhen bathing, showering, and cooking

• After flooding, remove any wet or damp material right After flooding, remove any wet or damp material right away and start drying (with fans). away and start drying (with fans). Pull up carpets. Pull up carpets.

* * Mold in My Home: What Do I Do?Mold in My Home: What Do I Do?,, CHDS 2004 CHDS 2004