Page 379 - Construction Waterproofing Handbook

REMEDIAL WATERPROOFING 8.39
If the divertor system has failed completely, the cladding must be treated with a barrier
waterproofing system that is likely to completely change the appearance of the facade.
Barrier systems that are applied to masonry walls include the cementitious systems
described in previous sections. In addition, an elastomeric coating can be used, providing
that deteriorated mortar joints are treated first. Both these repair methods will change the
aesthetics of the existing cladding.
In certain situations, testing and investigation might reveal that infiltrating water is
caused by water entering an adjacent envelope component and traveling to the divertor area,
exceeding the capability of the system to adequately control the flow of water. For exam-
ple, precast panels above a window or curtain wall might permit water to travel through the
precast and down into the integral window head flashing. While it might appear the window
is contributing to the leakage, the leak investigation should confirm that the precast is caus-
ing the problem. In this situation, the precast should be repaired and sealed to properly elim-
inate the water infiltration.
When retrofits or additions are involved to existing structures, care must be taken to
preserve the integrity of the existing envelope. Manufacturers should be consulted to deter-
mine appropriate transition details between new envelope components (including water-
proofing systems) and existing systems. In addition, building owners are to verify any
current warranties that might be voided by renovation work adjacent to or on the existing
systems. Chapter 10 presents in detail appropriate termination and transition details that
can be used in retrofits and remedial applications.
Anywhere that a new envelope component meets an existing component, the applica-
tions methods presented in the previous chapters should be closely followed. For example,
installation of a new concrete wall adjacent to an existing wall should not prevent the instal-
lation of waterstop to adequately seal the envelope. There are remedial waterstop systems
to properly tie the concrete placement together as shown in Fig. 8.42.
It is important to remember that all proper waterproofing practices presented in
Chaps. 1 through 7 should be implemented on remedial applications. Since many remedial
repairs are necessitated by these principles, superior installation methods for remedial work
can prevent the 90%/1% and 99% principles from reoccurring.

RESIDENTIAL BASEMENT RETROFITS

Residential basements often experience leakage, often because of the 90%/1% and 99%
principles, but also due to residential contractors not taking necessary precautions in the
original construction to protect the interior areas. Since most basement walls are con-
structed of concrete or concrete block, all the products covered in Chap. 2 are applicable
in residential construction. This includes both positive- and negative-side applications.
For remedial treatments, if the interior side of the basement is accessible (including
through removal of paneling or drywall), negative cementitious applications make excel-
lent choices for repairs. Often the critical floor-to-wall juncture is the point of least resis-
tance to leakage, and installing a cove or cant with metallic or high-strength cementitious
grout will correct the leakage problem. However, it is important to recognize that the entire
basement floor-to-wall joint must be repaired, otherwise the leakage will just move to the
next path of least resistance.