Weep

A weep, a weep hole, or a weep-brick is a small opening that allows water to drain from within an assembly. Weeps are located at the bottom of the object to allow for drainage; the weep hole must be sized adequately to overcome surface tension.

Weeps may also be necessary in a retaining wall, so water can escape from the retained earth, thus lessening the hydrostatic load on the wall and preventing moisture damage from freeze/thaw cycles. In such cases the weeps consist of small-diameter plastic, clay or metal pipes extending through the wall to a layer of porous backfill.