Weep holes are installed in a masonry wall inside the wall cavity and above grade. Their purpose is to collect and drain any water or moisture near the bottom of the wall that may have penetrated the outer wythe of wall, and to send it back to the exterior of the wall. Masonry will absorb water during rains and it will be stored to eventually be deposited to the cavity of the wall. Weep holes are typically spaced 3′ maximum but may be less depending on architects specifications. The holes are often formed with short lengths of cord inserted by the mason or or by oiled rubber tubing.
The 3 primary types of weep holes are:
Open Head Joint – Mortar is omitted to allow for weeping of cavity moisture. Also a mesh like material or screen material can be used to maintain the opening and keep animals and insects out
Rope Wick Method – A rope is placed through the mortar joint and up the cavity wall slightly to obtain and weep moisture to the outside. Sometimes oiled rope is used which can be removed after the fact which mimics the tube method.
Tube Method – Often a hollow plastic tube placed in the mortar joint which receives moisture and wicks it to the exterior. Sometimes a combination of tube and wick is used utilizing the benefits of both approaches.
The material used will extend upward into the cavity just past the mortar dropping forming a drainage channel to collect water. Weep holes should be small enough to prevent small rodents and insects from entering the building, but large enough to accept and convey water to the exterior.