A sealed and thermally insulating tank for storing a low-temperature liquefied gas, having an insulating box-section with a bottom panel coming into abutment on a support wall, by means of sealant beads disposed between the support wall and the bottom panel, the sealant beads being disposed in the form of at least one closed outline delimiting at least one confined space between the support wall and the bottom panel, the bottom panel having at least one through passage leading into the confined space to allow gas to circulate between the confined space and an internal space of the insulating box-section.