Weeps come in a variety of types, materials, styles, etc. The most common types are simply small holes (usually about 1/4-inch in diameter) in the mortar joints or unfilled head joints (the vertical joints between two bricks). Other types feature wicks, plastic tubes or vents.
Wick-style (rope filled) weeps are among the least desirable as they can become easily congested with water-soluble solids, rendering them ineffective. Furthermore, physical removal of congested wicks is not often possible without causing damage, since the rope is usually adhered to flashings or the surrounding mortar.
Open-style weeps can also become obstructed (with debris, spider webs, insect carcasses, etc). It is common to cover the openings with screens or similar provisions to maintain a clear pathway for the draining moisture.
Weeps are generally located where flashings are present. The weeps should be located at the level of the flashings (not several courses above) and spaced no greater than 24 inches, on center. If wicks are used, then the spacing should be reduced to 16 inches.
|
|
We have seen instances where weep holes have been sealed in an effort (usually futile) to prevent leakage. In most cases this is counterproductive because avenues of escape are eliminated. Interior leakage is more often the result of defective flashings. On the other hand, we have seen instances where weep holes were installed without flashings. Those are just holes and should be sealed.
Adding weeps to compensate for insufficient or dysfunctional ones should only be undertaken with great care, after thorough investigation. The flashing material is likely to be very fragile (thin gauge metal, plastic sheet goods, etc.) and easily damaged. Weeps should never be installed in systems that lack appropriate provisions to collect and/or divert water away from sensitive areas toward the weep.
Weeps are also common features of retaining walls and serve a similar function (removing water from places where it can cause problems). In retaining walls the main objective is to alleviate hydrostatic pressure which can exert sufficient force to damage the wall. The critical back-up elements for retaining wall weeps are drainage and filtration. Drainage features (layers of gravel, manufactured media, etc.) get the water to the weeps quickly. Filtering (screening, geotextile fabrics, etc.) helps prevent the soil from being carried out with the water. Just as with building wall systems, merely putting holes in retaining walls doesn't make them weeps.
Kirk Parsons
|
