Filler Slab is a concrete slab that is used to fill in gaps or voids between structural elements, such as beams or columns. It provides a level surface and may also serve as a base for other finishes or coverings. Filler slabs can be used in various parts of a building, including floors, ceilings, and roof decks. They are often used to create a smooth and even surface, and may also be used to improve insulation or soundproofing.