Riser voids are openings left to accommodate mechanical and electrical services on multiple floors of a building.
The frame features a GRP profile which comes as a standard depth of 300 mm but can be cut down to suit, according to the company. Once the frame is made, composite open mesh grating is cut to fit and dropped onto the frame.
According to Step on Safety, the GRP units are supplied prefabricated and complete with fixings so can be more easily placed in position before the floor is poured.
They are also lighter than steel equivalents and can withstand a minimum uniformly distributed load (UDL) of 5kN/m2.