Although ribbed slabs are deeper than flat slabs, the amount of concrete and reinforcement is considerably less, with a saving of about 20% in the volume of concrete and 10% in the weight of steel. This means smaller loads, resulting in slimmer columns and less extensive foundations. Ribbed slabs can also be post-tensioned, which reduces the concrete volume by a further 10%. Read more in 'Return of the Rib' article inConcrete Quarterly, summer 2019.