Environmental Engineering Reference
In-Depth Information
Figure 6.9
Stachybotrys
and other mold species growing on ceiling tile.
ing leaks without timely maintenance may result in significant water damage
and mold infestation problems.
Floods associated with plumbing failures are not uncommon in build-
ings. They may arise as a consequence of breaks in potable or mechanical
system water lines, or sewage water backups. Significant wetting of building
materials may result, depending on the amount of water released or the
extent of sewage backup. The probability that significant mold infestation
will occur also depends on how quickly building facilities personnel/home-
owners dry the wetted materials. The window for such drying is believed
to be 24 to 36 hours; i.e., if flooding cleanup and material drying can be
accomplished within 24 to 36 hours, little to no mold infestation should
occur. Sewage backups pose problems of both water damage, mold infesta-
tion, and potential problems of odor and contamination of building materials
with fecal bacteria.
Overflow of sinks and bathtubs (typically associated with inadequate
supervision of children) is one of the most common flooding problems in
dwellings. Another common problem is poorly constructed and/or main-
tained shower facilities, wherein water penetrates wall cavities through inad-
equately grouted tile or windows. Poor use of shower curtains is also a minor
cause of water damage to bathroom floors.
Small floods may occur in mechanically ventilated buildings when cool-
ing coil units freeze in air handling units as a consequence of cold outdoor
temperatures.
Severe flooding in buildings typically occurs as a consequence of cata-
strophic events. Most notable are structural fires that are extinguished with
water, and natural disasters when rising water enters buildings. In such
cases, structural damage and mold infestation are often very severe. These
events represent worst-case scenarios of building mold infestation, associ-
ated exposure and health risks, and mitigation requirements.
