This is the oldest & the conventional method of waterproofing flat roofs.This is traditionally done by laying of brick bats on the slab which is covered with cement sand mortar or final finish of broken tile pieces, (more popularly known as china chips finish)as desired by the client.
Water proofing with Brick bat Coba is done by exposing the RCC slab to its bare surface Clearing the surface of all Lose particles and dust, Carting away of debris and spreading neat cement slurry mixed with waterproofing compound on the cleaned surface, filling up the uneven surface, honey combing etc. Spreading of CM(1:5) mix, mixed with water proofing compound and grouting brick bat in the mortar with necessary slope of approx. 1 in 100 for easy flow of water. Filling the joints in the bricks with the mortar properly. This treatment to continue along the inner side of the parapet or other adjoining wall up to a height of 30cm in the shape of a round wata and finally converting the top surface with jointless waterproofing cement sand mortar 1:4, 20 to 25mm thick finished smooth with trowel in cement colour marked into 30cms x 30cms false squares. The average thickness of complete treatment shall be 100mm. Curing to be continuously done for surface.