Page 424 - Construction Waterproofing Handbook

10.26 CHAPTER TEN
It is the lack of such systems, or inattention to proper application of these transitory
materials, that leads to most leakage in an envelope. It is the 1 percent of detail problems
that causes 90 percent of water infiltration problems.
After all the major envelope components and their transitions and termination details
are complete, a review of the total envelope is made to ensure it will act cohesively. This
review should begin by ensuring that all types of water reaching an envelope drain away
quickly. This prevents unnecessary infiltration and weathering of envelope components.

DRAINAGE REVIEW

An important point in reviewing any particular building envelope, existing or in design, is
that water should be shed and removed from a building as quickly as possible. From below
grade to roof, faces should be sloped whenever possible to shed water quickly.
Drainage must be provided to remove this water from surrounding areas. This not only
prevents water leakage but also prevents premature weathering or wear of building
envelopes from sources such as acid rain, chloride contamination, algae attack, and stand-
ing ponding water. Refer to Fig. 10.27 for recommended drainage requirements.

FIGURE 10.27 Below-grade envelope drainage detailing.