Page 398 - Construction Waterproofing Handbook

9.8 CHAPTER NINE
water infiltration. If the 90%/1% principle is not adhered to in these specific areas, especially
given that few commercial buildings allow for widows to be opened by occupants, the failing
becomes a health issue when mold grows owing to water infiltration in this 1 percent of the
building’s area.
Both commercial and residential air-conditioning units can be a cause of mold contam-
ination and can contribute to the spread of spores though the duct work. All HVAC sys-
tems have some means of draining off the condensate that forms when the air is cooled,
and if the drip pan piping that drains the condensate becomes clogged, an area can be cre-
ated that encourages mold growth, and the spores can be spread throughout the building as
air circulates around the clogged drip pans.
While commercial air-conditioning units are inspected regularly by maintenance per-
sonnel, residential owners rarely inspect their air-conditioning units. This is why most
local residential building codes require that condensate overflow piping exit somewhere
outside the residence where it is readily visible by the occupants so that they realize that
the drip pan has become clogged so as to prevent damage from condensate overflowing the
pan, as well as preventing the formation of mold in the attic and other areas where the units
themselves are located. The reason for such code provisions is that homeowners rarely
inspect their air-conditioning units unless a problem develops, so this condensate overflow
is necessary to alert the homeowner of an unsafe condition.
Commercial or residential structures with flat roofs that use scuppers or roof drains for
drainage also should be inspected regularly. Clogged roof drains or scuppers can become
areas of mold growth, particularly if leaves are clogging the drains because they provide a
perfect food source for mold. This mold then can enter the structure in numerous ways,
from mold spores being pulled in though air-conditioning or heating inlets to spores that
enter with water through leakage areas at widows when the rain water overflows and
washes down the side of the building instead of through the gutter.

SUMMARY

Mold is often the first sign that a structure is experiencing water infiltration because evidence
of mildew or mold growth may come when leakage starts and has not noticeably saturated
an interior area. Other than interior bathrooms and utility rooms, where humidity levels pre-
sent opportunities for growth, mold and mildew typically are a sign of water infiltration.
Anytime mold or mildew is located, testing for the cause of water infiltration should be
undertaken, but protection from contamination from the mold also should be provided.
However, again, it is critical to always cure the source of water infiltration prior to under-
taking mold remediation.
Chapter 11 presents detailed information about leak investigation and detection for any
areas where mold is discovered. Chapter 7 then can be used as a resource for selecting a
remedial waterproofing system to correct the leakage found that is creating the moisture
source for mold growth.