Shear strength of precast concrete ribbed slabs reinforced with electro-welded lattice girders of variable height is experimentally verified. Technical justification is given for the use of high latticework in the reinforcement of precast lightweight double-tee ribbed slabs and precast reinforced concrete slabs 30 cm in thickness. It was established that the contribution of concrete to shear strength was always higher than the expected values according to Spanish standards. Furthermore, as low lattice ribbed slabs exhibited lower ultimate shear strength values than the ones expected based on the standards, the need arose to provide an adequate height of lattices in ribbed slabs to ensure anchorage of the compressed area in order to develop the strut-and-tie mechanisms. Consequently, lattice girders with approximately 80% of specimen height are highly recommended in reinforced concrete ribbed slabs, when the length of lattice chords is 20 cm.
