Reinforced concrete ventilated screed, made with high compactness and moderate shrinkage water-repellent concrete HA-25 N/mm2, plastic consistency, Tmax.20 mm, for type IIa environment, designated as HA-25/P/20/IIa, prepared in central, in compression layer of Y cm, even poured, placed and reinforced with mesh 15x15x6, pp of joints, sawing them, compacted, p.p. of vibrating, screeding, troweling, curing and permanent formwork for the formation of ventilation with a raised floor by means of a chamber, Caviti type of thermoinjected recycled PP-PET prefabricated modular elements. The modular pieces CAVITI® C70 with a height of 70 cm adequate to the useful overloads expressed in the calculation documents and foreseen geometries. Including the supply of parts and assembly, following the indicative arrows printed from left to right in rows, forming every four modules, a hermetic support pillar on the support surface (base module 750x500 mm 2.67 pillars m2 resulting in a surface of support of 743 cm2/m2), which will be filled with concrete. Fully finished. Including transportation to the concrete work, cutting of pieces for special solutions such as the meeting with supports and final closing pieces (if necessary), proportional part of auxiliary means and small material. According to NTE-RSS and EUROCODE. Measurement criteria: projected area according to graphic documentation of the Project. Product with EPD Certificate.