This document discusses various methods for preventing dampness in buildings, including damp proofing courses, integral damp proofing treatments, and waterproof surface treatments. It provides details on proper installation of horizontal and vertical damp proofing courses, and notes that the selection of damp proofing method depends on factors like the surface type, structure location, and subsoil water table. Key damp proofing methods covered are membrane damp proofing using courses, integral treatments by adding components to concrete/mortar, and applying water-repellent substances to surfaces.

1. DAMPNESS AND
PREVENTION OF DAMPNESS

2. General principles of
Damp proofing
 The D.P.C. should be horizontal or Vertical.
 The horizontal D.P.C. should be provided for full thickness of
the wall.
 The D.P.C. should be continued unbroken throughout the
length of the wall.
 Lap joints should be properly sealed with bitumen.
 The mortar bed which is prepared to receive the horizontal
D.P.C. should be even.
 It should not be kept exposed on the wall surface otherwise it
is likely to get damaged.

3. Methods of Damp Proofing
There are various methods of damp proofing and depending
upon the nature of surface, situation of the structure and amount of
dampness, the proper method is selected.
Following are methods or measures adopted to prevent entry of
dampness:
 If the level of the ground floor is in level with the ground surface or
just above it, the damp proofing course is provided. The material
should be flexible.
 If two ground floors at different levels are connected by an external
wall, the damp proofing course on the internal wall is in level with
the lower floor level.
 In order to prevent the rising of moisture from the adjacent ground,
the air drains may be provided. An air drain is a narrow hollow
space which is constructed parallel to the external wall. The width of
air drain is about 200 mm to 300 mm.

4.  In case of basements, the damp-proofing course should
properly provided. Otherwise basements become useless for
the storage of materials unaffected by damp. The treatment of
asphalt tanking is adopted when the subsoil water table is not
very high.
 In case of sloping ground, damp-proofing course should be
stepped such that it remains at a minimum vertical distance of
150 mm above ground. The damp proofing course may be of
any suitable flexible material such as bituminous felt, etc.
 The construction of cavity walls considerably prevents the
entry of damp inside the building suitable damp-proofing
courses may be provided on these walls.
 The provision of coping on a wall prevents considerably entry
damp from the top surface of wall.

5. There are various methods of damp-proofing but adoption of any
specific methods depends on following factors:
 Depending upon the nature of surface.
 Location of the structure.
 Sub-soil water table.
 Amount of dampness to be handled.
Following methods are adopted to make a building damp proof:
1. Membrane Damp proofing (use of damp proofing course) (D.P.C).
2. Integral damp proofing.
3. Water proof surface treatment.
4. Cavity wall construction.
5. Guniting or shot concrete.
6. Pressure grouting or cementation.

6. 1.MEMBRANE DAMP PROOFING
This consists of introducing a water repellent membrane
or damp proofing course (D.P.C)between the source of dampness
and the part of the building adjacent to it. Damp proofing course
may consist of flexible materials such as bitumen, mastic asphalt,
bituminous felts, plastic or polythene sheets, metal sheets, cement
concrete, etc. Damp proofing course may be provided either
horizontally or vertically floors, walls, etc. Provision of D.P.C in
basement is normally termed as tanking.
The best location or position for D.P.C, in case of
buildings without basements , lies at the plinth level or in case of
structures without plinth it should be laud at least 15 cm above
the ground level.

7. 2. INTEGRAL DAMP PROOFING
The integral treatment consists adding certain components
to the concrete or mortar during the process of mixing, which
when used in construction, act as barriers to moisture penetration.
Such compounds are available in market in powdered as well as
liquid form.
The quantity of liquid water proofing compound to be
added cement depends upon the manufactures recommendations.
In general, one kg. of water proofing compound is added with
one bag of cement to render the mortar or concrete water proof.
The compounds like alkaline, silicates, aluminium
sulphate and calcium chlorides react chemically and fill in the
pores to act water resistant.

8. 3. WATER PROOF SURFACE TREATEMENT
The surface cement consists of application of layer of
water repellent substances or compounds on these surfaces
through which the moisture enters. The use of water repellent
metallic soaps such as calcium and aluminium oleates and
stearates is much effective in protecting the Building against the
ravages of heavy rain. Bituminous solution, cement coating,
transparent coatings, painting and distempering fall under this
category. In addition to other treatments given to walls, the one
commonly used is lime cement plaster. The walls plastered with
cement, lime and sand mixed In proportions of 1:1:6 is found to
serve the purpose of preventing the dampness in wall due to rain
effectively.