Page 395 - Construction Waterproofing Handbook

MOLD 9.5
• Humidifier overuse
• Leaking plumbing or appliances such as washing machines
• Poor insulation around ducts that results in condensation and high humidity in living areas
Each of these or any combination can provide sufficient conditions for mold growth.
While some mold formation is readily visible, such as the mold on the tile grout of shower
walls, mold may grow in other areas that are not readily accessible and may require thor-
ough inspection. For example, mold may grow behind a finished wall as a result of leak-
age from a water pipe that the homeowner inadvertently damaged when hanging a picture.
Such instances usually are readily identifiable as non-water-leakage building envelope
problems and are reparable without addressing building envelope components.

BUILDING ENVELOPE CAUSES

Any leakage through a building envelope into heated spaces that have organic building fin-
ishes such as drywall, grout, carpet, or other finishes eventually can lead to the formation
of mold, mildew, and fungi. Besides the serious health issues that mold can create, as
addressed earlier, mold also can destroy the usefulness of the finishes themselves.
Furthermore, while the water leakage itself may not spread to cause more damage, the
resulting mold growth can expand until the entire building is designated as uninhabitable
with sick building syndrome. Repair costs in such cases far exceed the cost of building
envelope repairs and literally may require the entire building to be torn down to its struc-
tural components and rebuilt to effectively remove all traces of mold and spores.
Prevention of mold is another important reason for adequately designing, specifying,
constructing, and maintaining a watertight building envelope following the principles dis-
cussed throughout this book.

Below grade
An edible form of mold/fungi—mushrooms—actually is grown commercially in basement-
like settings, suggesting that most below-grade structures are likely areas to support the
formation and growth of mold and mildew. The high humidity levels often found in base-
ments owing to poor ventilation of below-grade areas and the presence of water leakage
through the building envelope merely require the addition of organic building finishes such
as carpeting to foster the growth of mold, mildew, and fungi.
In many basements or similar below-grade areas you will find the strong musky odor of
mold readily apparent. Often, particularly in residential structures, you are likely to find
dehumidifiers running constantly to remove the constantly present moisture. This moisture
is likely caused by poorly designed and constructed below-grade structures in combination
with poor surface drainage and groundwater control.
In residential structures, a structurally sound basement may be susceptible to mold forma-
tion owing to the addition of windows—added for light—that are actually below grade. Such
windows are protected by the addition of a galvanized metal barrel–type surround that permits
light to enter the window, but it also permits standing water to collect near the window if sur-
face water and groundwater are not drained adequately and sloped away from the structure.