Page 30 - Construction Waterproofing Handbook

1.12 CHAPTER ONE
contraction while maintaining a watertight facade. Note that the brick also has been
detailed with through-wall flashing, diverting intruding water vapor and moisture that was
collected by the dampproofing back out through the provided weep holes. Additionally,
sealant at the window perimeters acts as a transition between brick facade shelf angle and
the window frame. The window frame then acts as a watertight transition between the
frame and glass, both being waterproof themselves.
To transition between the barrier waterproofing system used below grade to the
drainage system (brick facade), a reglet is installed. This reglet provides the detailing nec-
essary to transition between the two systems while maintaining the watertight integrity of
the envelope. Additionally, sealant is installed in the reglet to allow the systems to move
independently at this point but still remain waterproof.
Even the waterstop shown in the concrete foundation provides a very important transition-
ing and waterproofing detailing that is often overlooked. In this wall section, the waterstop
effectively ties together the vertical waterproofing to the horizontal slab waterproofing,
providing a watertight seal by prohibiting the lateral movement of water along the concrete
wall to foundation joint.
The Fig. 1.9 wall section also details divertor systems by sloping of the adjacent soil or
landscaping and installing a French drain system. Each system, while not in itself neces-
sary for the waterproofing of the building envelope, quickly removes water away from the
structure, eliminating unnecessary hydrostatic pressure against the foundation walls.
As illustrated in Fig. 1.9, each separate waterproofing material effectively joins
together to form a watertight building envelope.

THE MOST IMPORTANT WATERPROOFING PRINCIPLE

Each separate envelope trade contractor’s work, regardless of its being thought of as a
waterproofing system or not (e.g., exterior mechanical apparatus), must become part of a
totally watertight building envelope. Equally important, all individual envelope systems
must be adequately transitioned into other components or provided with watertight termi-
nations. Often the tradesworkers completing this work are not aware of, trained in, or super-
vised in enveloping a building properly. And this is the number one cause of water
infiltration in all types of structures.
The resulting improper attention to details is responsible for countless problems in con-
struction. Properly detailing a building’s envelope presents an enormous task. From incep-
tion to installation, numerous obstacles occur. Highlighting this interrelationship of
various envelope systems is the most important principle of waterproofing:
The 90%/1% principle: 90 percent of all water intrusion problems occur within
1 percent of the total building or structure exterior surface area.
This 1 percent of a building’s exterior skin area contains the termination and transition
detailing, as discussed previously with Fig. 1.9. This 1 percent area all too frequently leads
to breaches and complete failure of the effectiveness of the building envelope and is the
main cause of all waterproofing problems.
Industry members, including contractors, designers, and manufacturers, now are recog-
nizing the importance of the 90%/1% principle first introduce by the author. Architects must