A flashing and weep apparatus allows for simple installation and accurate placement windows and doors in cavity wall construction. In a first embodiment, the flashing and weep apparatus is a two-panel extrusion that has a flashing panel that acts as a non-porous support for the masonry veneer. This embodiment also includes a second panel which is joined at a generally right angle to the first panel to be juxtaposed against the outer face of the inner wall in the cavity wall construction. Weep channels are formed between the two panels and allow for the drainage and dissipation of water and other moisture in the cavity wall system. In a second embodiment, membrane is initially attached to and draped along the lower portion of the inner wall immediately above the sill or lintel. The membrane extends across the cavity spacing between the walls to underlie the masonry components forming the outer veneer. Weep channels on the membrane communicate and transmit water and moisture from the cavity between the walls to the exterior of the veneer. The weep channels are positioned at the joint between adjacent bricks. The membrane extending beyond the mortar joint at the masonry veneer is trimmed during the installation process so as not to extend beyond the outer veneer wall while still providing an easily installed and implemented flash and weep system.