Slab which is provided below the washrooms to hide the sewage pipes or sewerage pipes is called Sunken slab. Since the pipes that carry water are concealed below the floor, care has to be taken to avoid leakage problems. After casting sewage pipes in the slab the slab is filled with coal or broken pieces of bricks. There are two types of sunken slab.
- The slab which is provided below the normal floor level at a depth of 200mm to 300 mm and filled with broken pieces of bricks is called Sunken slab.
- The Slab which is provided above the normal floor level at a height of 200mm to 300mm and filled with coal or broken pieces of bricks called sunken slab.
Construction Method of a Sunken Slab
The concrete of the R.C.C. (floor and sunken slab) should mixed with a waterproofing material to get a denser, watertight concrete.
Then cement and waterproofing material should be diluted in water and splashed onto the RCC sunken slab. Over that a layer of plaster should be provided using a mortar plasticizer with the cement mortar.
Brick laying of walls and plastering (prior to tiling) of the walls and floor should be done with cement mortar mixed with a mortar plasticizer.
Tile fixing for the floor and walls tiles should be done with non-shrink, waterproof tile adhesives to make the tiled area waterproof.
Sanitary pipe joints should be sealed with sealants specially manufactured for Sealing Sanitary joints firmly so that no water can leak through.