The I-void system is a recycled polypropylene formwork that was designed to create lightened slabs and raft foundations. The I-void box is elevated by the use of four conic feet; they create a grid of perpendicular I-section beams, only the inefficient concrete is removed, while the compression and tension areas remain untouched. This results in considerable reduction of concrete (30 to 35%), while its inertia stays almost the same. The reduction in load leads to smaller deflections and less reinforcement.
The I-void system is used to create slabs with large span or that are able to support large loads without drop beams. They are light, quick and easy to position, thanks to their modularity the designer can vary the geometric parameters as needed to adapt to all situations with great architectural freedom.