Page 396 - Construction Waterproofing Handbook

9.6 CHAPTER NINE
The standing water increases humidity levels in the warm interior areas or actually penetrates
the envelope through joints adjacent to the window or between the windowpanes themselves.
A recurring situation in residential basement construction is installation of a laundry
room in the basement without proper detailing to provide adequate ventilation for the dryer
to prevent moisture and humidity from reaching levels that can create conditions for mold
growth. Dryer vents are often installed through venting that rises above the basement level
and out through outside walls above grade. This is necessary because venting is not possi-
ble through outside walls that are backfilled with soil against them. If the venting is not
deigned properly, the moisture-laden air from the dyer may not be removed and may cre-
ate high humidity in the basement. This also occurs in bathroom areas below grade that do
not have sufficient mechanical ventilation to move the moist air out, leading to mildew and
mold growth in the bathroom and possibly surrounding areas.
Many residential basements may not have been designed as a finished area, but later the
homeowner applies organic building materials such as drywall, and soon mold contamina-
tion affects the entire structure. In older basements, particularly those with sump pumps,
standing water often collected from groundwater drainage stands in the sump pump area to
be pumped outside when the water reaches a certain level. The sump pump area provides
constant moisture that easily could lead to mold growth if organic finishes are present in the
basement. Usually these areas were never intended to be finished but rather were designed
to remain with nonorganic, nonpermeable surfaces such as concrete. For such areas to be fit-
ted out for typical building interior finishes, the sump pump area would have to be removed
or isolated prior to finishing of the basement area.
It is also common in older residential construction that the basement areas were con-
structed using damproofing protection only, not waterproofing materials, and again, they
were meant only for storage or for use as a laundry area. Application of organic finishes in
such basements without prior application of remedial waterproofing systems often leads to
mold and mildew problems.
In all types of older structures, mold often is found during interior renovations when
organics finishes such as drywall or paneling are removed from exterior walls. It is therefore
recommended that in any below-grade area that is being renovated for interior building fin-
ishes as a living or working space, the entire below-grade structure should be examined for
water infiltration and that both surface water and groundwater controls should be reviewed
or installed as necessary prior to the start of renovations.
Below-grade structures should follow the guidelines presented in Chap. 2 anytime
there is an intention to use organic interior finishes in those areas to prevent the forma-
tion of mold and mildew. Particular attention should be paid to ensuring that the enve-
lope is continuous around the foundation forms a watertight and moisture-tight barrier
between the vertical and horizontal areas. Often in residential construction the founda-
tion is constructed with no attention to proper waterproofing details for the transition
between the horizontal and vertical areas of the basement. For example, rarely will you
find a residential builder using the water stop required in a common basement construc-
tion detail.
All too often residential contractors will merely apply a vapor barrier to the horizontal slab
portions and neglect to add a proper waterproofing membrane below the slab (refer to the sec-
tion on vapor barriers in Chap. 2). When organic carpet and padding are installed on the