Waffle Slab

What is a Waffle Slab

Definition of Waffle Slab in Construction

The term waffle slab is used in commercial or larger scale residential construction to describe a type of concrete slab formwork. The formwork consists of individual forms that resemble the individual segments of a waffle consisting of an open box, with four sides and an open top. These waffle segments are assembled on a wood deck that is supported by temporary shoring. The boxes are located adjacent to each other with the open portion of the box facing downward on the wood deck. The final appearance of the deck, prior to the placement of concrete is a large series of upside down boxes, with a pre-engineered spacing between each box. The tapered sides of each adjacent box or waffle form are separated to allow the installation of concrete between the boxes. The entire assembly is covered with concrete to the established depth, as engineered by the structural engineers for the project.

The concrete is allowed to cure and the temporary supports, the wood deck and then the waffle formwork is removed. The resultant concrete deck now consists of a network of small beams or supports that appear to resemble a waffle when viewed from the bottom. These small, thin tapered concrete components, will provide the support necessary to properly support the concrete deck that has been placed above them. This manner of construction allows the thinner concrete slab as well as the ability to install lighting, up in the boxes formed on the underside of the slab. The use of the waffle slab, type of construction is starting to diminish with the introduction of stronger concrete mixes, post and pre-tension concrete as well as specialized types of formwork that are allowing stronger and thinner concrete slabs to be constructed.