damp proofing course

Damp Proofing Course

Materials & Details Prepared by: Ar. Ramandeep

Lecture-10

05.09.2014

What is Damping?

Presence of unwanted

moisture in the structure of

a building, either the result

of intrusion from outside or

condensation from within

the structure.

Lecture- 10 | Damp proofing | 05.09.2014

Faults & Defects

Roofs

Beam Roof joint

Beam column joint

Sill- wall joint

Floor- wall joint

Walls


Effects

Reduction in strength of structural components of the building

Unhygienic conditions

Unsightly patches

Softening & crumbling of plaster (lime plaster)

Flooring gets loosened because of reduction in adhesion when moisture enters through the floor.


METHODS OF DAMP PROOFING

Use of DPC- membrane damp proofing

Integral damp proofing

Surface treatment

Cavity wall construction

Pressure grouting


Membrane damp proofing

Consists of introducing a water repellent

membrane or DPC

between the source of

dampness & part of

building adjacent to it.

Use of DPC- membrane damp

proofing


Surface treatment


Pressure grouting


Membrane damp proofing

May consist of flexible materials such as

1. Bitumen

2. Mastic Asphalt

3. Bituminous felts

4. Plastic/ Polythene

sheets

5. Metal sheets

6. Cement concrete etc

Use of DPC- membrane damp

proofing


Surface treatment


Pressure grouting



Adding certain water proofing compounds or

materials to the concrete

mix, so as to make it

permeable



Surface treatment


Pressure grouting



Compounds made from chalk, talc, fullers earth, - which will fill the concrete voids

Compounds like- alkaline silicates, Aluminium sulphates, calcium chlorides, etc.

Compounds like soap, petroleum, oils

Fatty acid compounds such as stearates of calcium, sodium, ammonium, etc.



Surface treatment


Pressure grouting


Surface treatment

Application of a layer of water repellent substances or compounds on these surfaces through which moisture enters.

Water repellent metallic soaps such as calcium & aluminium oletes & stearates (effective for rain water penetration)



Surface treatment


Pressure grouting


Cavity Wall construction

Effective method of damp prevention

Main wall of building is shielded by an outer skin

wall, leaving cavity between

the two.



Surface treatment


Pressure grouting


Pressure Grouting

Consists of forcing cement grout, under

pressure, into cracks,

voids, fissures etc.

Structural components and foundations are

liable to moisture

penetration



Surface treatment


Pressure grouting


Grouting Procedure


Guniting

Depositing, under pressure, an impervious layer of rich cement mortar over exposed surfaces for water proofing, for resisting water pressure.

Cement mortar ratio- 1:3 cement sand mix.

Shot on cleaned surface- with cement gun, under pressure- 2 to 3 kg/cu cm.



Surface treatment


Pressure grouting

Guniting


Materials used

Hot Bitumen Highly flexible material

Min. thickness- 3 mm

Placed on concrete bedding

Mastic Asphalt Semi rigid material

Durable and completely impervious

Obtained by heating asphalt with mineral filler & sand

Liable to squeeze out in very hot climate/ heavy pressure


Materials used

Bituminous or asphaltic felts Flexible material Available in rolls of various wall thickness Laid on levelled flat layer of cement mortar Cannot withstand heavy loads Can accommodate slight movements

Metal Sheets Sheets of lead, copper, aluminium Flexible Thickness should be such that weight is not less than 20 kg/

sq mt

Laid similar to bituminous felts.


DPC Treatment for basement on undrained soils.


Plan of building showing DPC


DPC treatment for basement in damp soil


DPC for flooring


Asphalt tanking for basement

damp proofing course

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