sealing material but preferably a magnetically attractive material to hold them together when they butt together such as magnetized rubber the closure strips 76 78 may be fastened in corresponding grooves in the closure channels 72 74 or they may simply be applied to the butting surfaces of the closure channels 72 74 fig7 is a cross sectional view of a portion of the left door support panel 4 shown in fig1 a left wall sealing sheath 80 fits over the edge of the first left door panel sheet 68 described above in connection with fig6 the left wall sealing sheath 80 is positioned to butt against the left wall of the bathtub alcove the first left door panel sheet 68 is then slid within the left wall sealing sheath 80 to a desired position for best overall door panel alignment the left wall sealing sheath 80 is fastened by at least one wall mounting bracket 82 which clamps the sheath 80 to the door panel sheet 68 with for instance a clamping screw 84 and serves as a mounting surface for bolting or otherwise fastening the door assembly 2 to the wall of the bathtub alcove for convenience each wall mounting bracket 82 may be first fastened to the alcove.