the first gap 78 the structural middle wall 34 includes structural middle wall apertures 44 that transfer air from the first gap 78 to the second gap 84 the floating wall elements include floating wall element apertures 46 that transfer air from the second gap 84 to a hot gas flow path 88 the structural cold wall 32 and the structural middle wall 34 are joined with a joining member 40 they may be welded or bolted etc the manner of connection is only relevant to the extent that it provide sufficient strength to the structural cold wall 32 and the structural middle wall 34 the joining member 40 has a geometric feature 48 which can receive a floating wall element engaging feature 50 a specific configuration of the geometric feature 48 and the floating wall element engaging feature 50 is not required what is required is any configuration catches and u201c traps u201d permits the floating wall element 38 in such a manner that the floating wall element 38 is free to float expand and contract yet remain engaged with the geometric feature 48 the geometric feature 48 may be elongated such as a slot so that individual floating wall elements can be removed and or installed readily the edges of the wall assembly 30 can be sealed and damped or lead to other joining members 40 etc cooling can be provided as needed with dedicated cooling holes and or intentional leakage of cooling air from outside the iep 16 to inside for example by joining member cooling aperture 70 structurally the three walls are configured such that any mechanical load is isolated.