Weep No More
Have you ever seen holes or plastic tubes in the mortar joints just above the foundation and over windows and doors?
Sometimes there is a small length of rope sticking out of the joint instead of a hole. Note-- you aren't seeing sloppy construction,
the holes or piece of rope are supposed to be there. Don't seal them up because they serve a valuable purpose.
While a masonry wall is the first line of defense against
water penetration, it can leak. Masonry is porous and can
absorb moisture in extreme weather conditions. Weep
holes are the exit port for the drainage cavity behind the
masonry wall. If the wall is built correctly, the weep holes
allow moisture behind the masonry to exit. These holes
also serve as pressure equalizers making it less likely that
wind-driven rain will penetrate the wall. The drainage
cavity has five essential elements: 1) The exterior wythe
(the vertical section of a wall that is equal to the width of
the masonry unit) of masonry provides the first resistance
against moisture penetration, 2) An air space of at least
one inch, 3) An interior wythe of masonry or other material
such as frame wall, 4) Flashing at all interruptions in the drainage cavity such as at the base of the
foundation and around the openings for such windows, 5) Weep holes at all flashing locations-- recommended spacing of
33 inches.
For a cavity wall to function properly, water that collects on flashing must be able to drain through the weep holes to the
exterior or the building. If weep holes do not function properly, water collecting in the cavity can infiltrate the building
interior. There are many homes built with no weep holes that have or will likely never become a problem. However, good
building practices and most building codes suggest weep holes should be installed when the home is built. Many code
officials will look the other way or allow occupancy without the installation of weep holes.
Conversely, the absence of weep holes occasionally allows so much moisture to accumulate that metal fasteners turn to
rust, wood-destroying insects are encouraged, or rot develops. It is unlikely that a visual home inspection will reveal these
problems unless conditions are so severe that cracks in the
walls or other indicators are visible. The most likely visual
manifestation of a problem will be water stains, damp areas or
rot at the foundation plate and/or floor band as well as stains
or damp areas at the top of the foundation wall. Weep holes
can be added. However, most masonry experts question the
effectiveness of retrofit without at least partial removal of the
masonry, which is very expensive.
Home inspections are not code compliance inspections.
Professional home inspectors can look and determine if weep
holes are present, however, they have no way to ensure absence of hidden moisture damage without invasive investigation.
Therefore; it is our perspective that weep holes should be installed when they are missing on a property.
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