MATERIALS FOR DAMP PROOFING

The materials used for damp proofing are following:

1. Bitumen: it is highly flexible and can be applied with brush to the bedding of concrete or mortar in hot condition. Thickness of coat provided is approximate 3 mm.

2. Mastic asphalt: It is a semirigid material. By heating asphalt it is obtained with sand and mineral fillers. Perfectly it is impervious. It should be laid very carefully.

3. Bituminous or asphaltic felt: It is a flexible material available in rolls. It is provided with an overlap of 100 mm on sides on roof slabs and parapet walls. With bitumen the laps are sealed. They do not withstand against heavy movements.

4. Bricks: Good bricks are sometimes used to make damp proof courses with water absorption less than 5 %. In cement mortar the bricks are laid in two to four courses.

5. Stones: Stones like, trap, granite and slates may be laid over wall to its complete width as damp proof course.

6. Mortar: To make a water proofing course to foundations, ground floor slabs, top of parapet walls etc Cement mortar of proportion 1: 3 with small quantity of lime and water proofing agents are used. It can be used for plastering external walls.

7. Concrete: Before starting constructing walls ,to check the rise 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. As an additional precaution these coursesm can be provided with hot bitumen paint.

8. Metal sheets: Copper, Aluminium or lead sheets are provided to seal the construction joints. Bituminous seal is provided over these sheets.

9. Plastic sheets: for damp proofing Plastic sheets are very good course. They are made up of black polythene of thickness 1 mm.