A sunken slab or sunk slab is provided below the normal floor level in bathrooms, toilets, and laundry areas, where pipes or drainage systems are laid. It is constructed with the purpose of concealing all the pipes below the floor level to maintain the aesthetic appeal of the space.
All plumbing pipes are concealed inside the slab in this type of slab. To reduce noise during usage of the bathroom there is no need for special plumbing fixtures in the sunken slab. These slabs provide good plumbing systems and also used where security systems are to be installed..
This extra depth is used for placing pipes and utility ducts and then space is filled with sand or other light weight materials until the normal floor level. It is also known as sunk slab.