Abstract: A multi-lobed, double-wall inflatable vault includes a plurality of distinct, inflatable hollow beams. Each beam is formed by a single continuous envelope and has four zones including two lateral zones defining webs of the beam and upper and lower zones defining flanges of the beams. The beams are arranged side by side contiguously. Respective confronting webs of two adjacent beams are held opposite each other by respective continuous longitudinal flaps that can be joined by mechanical linking structure. Each flap has a T-shaped transverse cross-sectional configuration including two lateral flanges fastened to the envelope of the respective beam and a central tongue to be linked by the linking structure to the tongue of the flap of the adjacent beam.