A waffle slab gets its name for its appearance as it visually resembles its namesake, the food. Waffle slab is a reinforced concrete roof or floor containing square grids with deep sides. This type of slab is used in construction projects needing intense strength to weight ratios. Waffle slab is a popular option for commercial construction work such as industrial building projects, bridges and others needing extra stability.
Concrete slabs are created according to three basic designs of which waffle slab is the most innovative. Each slab design is focused on enhancing the structure’s strength to weight quotient. All three designs contain a flat top surface with modulated undersides which makes them different from one another. The modulated undersides can be ribbed, corrugated or waffle. Ribbed slabs are used to add foundation strength in one direction while corrugated slabs are used to prevent the foundation from sagging. The concrete waffle slab is used when the objective is to enhance the strength of the foundation in perpendicular directions.
Waffle slab is gaining in popularity in construction projects as they can be shipped to site in different modes including prefabricated, precast or to be poured on site. The prefabricated waffle slab costs higher than the other two options. The construction process involves a building system of concrete slabs shored up by columns. The monolithic poured concrete forms a flat top surface while rectangular grids form deep concrete beams on the under surface with the beams resembling waffle pockets spread at right angles. The visual from the underside is a waffle like look. Floor supporting columns are spaced at a standard distance of 30 feet on center.
Where to use
Waffle slab is not used in typical construction projects. They are used for specialized projects that involve clean rooms, spaces requiring seclusion from low frequency vibration or those needing low floor deflections. Waffle forms used for wall slabs are generally available in sizes of 6”, 8” or 10” with 45 or 90 degree forms. The waffle pockets in the slab provide two directional reinforcements facilitating significant structural stability without having to use extra construction material. The concrete waffle slab is often used for industrial and commercial buildings while wood and metal waffle slabs are used in many other construction sites. The main purpose of employing this technology is for its strong foundation characteristics of crack and sagging resistance. Waffle slab also holds a greater amount of load compared with conventional concrete slabs.