Waffle Slabs consist of coffers, or shaped voids, in soffits of slabs.
Information to provide in scheme design:
● 2-way waffle slab
● Thickness of topping
● Depth of ribs and distance of ribs from center to center
● Size of flat beams
● Clear floor height
Reasons to use this slab type:
Capabilities
● Suitable for long spans
● Voids can reduce the self-weight of slab
● Accommodates space for services installation and distribution through slab openings
● Flat beams can provide lateral resistance for wind loads
● Provides robustness
● Provides limited deflections
● General aesthetics
● Standardized formworks can be used to reduce construction time and effort
Disadvantages
● Aesthetics of underside of slabs is dependent on workmanship
● Service penetrations through rib beams will decrease their inherent strength and stiffness and can lead to reinforcement congestion within the beams
● Long construction time needed to construct void formers and reinforcement placement
● No stiffness or lateral system to resist lateral wind loads when there are no core walls in the design
● Standard formworks used can be quite expensive for low-rise structures
● More finishes work required for structures of large surface areas
