Page 394 - Construction Waterproofing Handbook

9.4 CHAPTER NINE
than application of chlorine (bleach). If bleach is used, a diluted application if more effective
than spraying bleach directly from the bottle. Usually, the bleach is diluted with two parts water.
Spray applications of hydrogen peroxide or bleach are only effective on nonporous
building materials, but they may be used on areas such as concrete, concrete block, and
other masonry that cannot be readily removed for remediation. Nonporous material such
as furniture is best treated by cleaning with a detergent cleaner rather than these spray
applications because the mold is not able to penetrate the surfaces and removal is usually
complete with a thorough cleaning of the surfaces.
Again, it is critical not to attempt to remediate badly infested porous building materials
such as ceiling tiles and drywall. These should be removed and disposed of properly and the
finishes replaced with new ones to ensure that the mold does not reappear, even if the source
of water is repaired. Prior to replacing such finishes, it is important to give the area sufficient
time to dry thoroughly. This will eliminate the possibility of mold returning unnecessarily.
It is also important to inspect beyond the initial layer of mold for deeper or wider infesta-
tion prior to remediation. For example, carpet may have molded down through to the padding
and even through the padding to the plywood substrate. In this case, the carpet, padding, and
possibly the infested plywood all must be removed for proper remediation and to prevent mold
from returning even if the water source has been eliminated. During this process, it is imper-
ative to carefully wrap and protect the materials to be removed before moving them through
other areas of the structure because any mold spores present in the materials can easily
become airborne and result in contamination in other areas of the structure.
Prior to attempting any mold remediation, a complete program plan should be written
out and each step carefully reviewed before work is begun. Adequate information resources
are available at libraries, on the Internet, and through your local or state health departments.

CAUSES OTHER THAN THE BUILDING ENVELOPE

While direct leakage through the building envelope is the main concentration of this chapter,
it is helpful to review other causes of mold infestation, particularly in residential construc-
tion, that a homeowner can address immediately without waterproofing repairs. Among the
most severe causes of mold infestation is flooding, whether it occurs from river overflows
or hurricanes. Flooding so severely damages building finishes, especially such organic
components as drywall and carpet, that nothing short of complete removal will remove the
mold and prevent it from returning after building repairs are completed.
In residential and single-family construction, there are numerous causes for the presence
of water, moisture, or humidity to support the growth of mold. In fact, mildew/mold growth
in bathrooms and particularly in showers is so common that there are numerous household
products sold in grocery stores for “remediation” of these areas. Other situations that occur
frequently in residential homes that lead to mold and mildew growth include

• Inadequate ventilation in laundry rooms or bathrooms
• Drying clothes inside or inadequate outside ventilation of a clothes dryer
• An excessive number of houseplants and overwatering of houseplants
• Indoor hot tubs, whirlpool bathtubs, and pools