Construction Monthly Magazine | Atlanta 2021 Build Expo Show Edition

A flap of excess membrane of the pre-applied
waterproofing must be left exposed above the shoring
wall in the transition area and remain viable so it can be
tied into the podium waterproofing at a later time. That
requirement was ignored. Instead, the transition strip
used to connect the two systems was removed. How
could qualified contractors do this?
The primary reason is that only a handful of people really
understand why that flap of random membrane is so
important. In this case, the concrete contractor did not
understand that the flap was a critical connector for the
two different systems. Because the overarching goal
was to just get the work done, the concrete crew cut the
membrane off at the top of the shoring wall and wadded
up the vertical leg into the corner of the form, making it
completely unusable.
It is at critical junctions like this — better known as
terminations, transitions, and penetrations — that 90
percent of all water intrusion has been documented to
occur. Considering the different contractors working on a
project and the various connections between systems, it
is easy to see why most leaks happen at these junctions.
SERIOUSLY, YOU COULDN’T
CALL FIRST?
By David Leslie, RWC
In the world of roofing and waterproofing, rarely does a
day go by when a colleague or client utters the dreaded
phrase, “So I have this situation …” I feel a pit forming in
my stomach when I hear those words, because they are
typically said long after a painless solution to the problem
is possible. After 30 years in the weather-barrier industry
as an installer, consultant, and manufacturer, I have been
involved in countless “situation” conversations and can
assure you they are no fun. Let me offer an example.
My team has a project right now that has Underseal preapplied,
below-grade waterproofing on the foundation
wall of a parking garage that will be tying into the podium
deck waterproofing. In this case, the “situation” occurred
after the concrete contractor had finished placing curbing
around the podium deck (Fig. 1).
The purpose of pre-applied waterproofing is to maximize
efficiency by casting the concrete wall against it,
eliminating the wasted space of a trench. The membrane
from the top of the shoring wall down (which was never
intended to see the light of day) is sandwiched between
the concrete wall and the surrounding shoring wall.
16 CONSTRUCTIONMONTHLY.COM
What is the fix for a situation like this one? Unfortunately,
the correction is often demanding and sometimes
completely unreasonable to perform. We see it every
day: Major grade beams cast without waterproofing, large
banks of utility lines running through the waterproofing
without being detailed. Truly, the only way to properly
correct those missteps is to jack out the concrete and
start over. But rarely can a project absorb the additional
cost or delayed schedule to make such extensive
corrections.
In the pictured example, the fill under the podium deck
must be excavated, exposing the membrane to install
a transition membrane. Making this correction after
the fact adds time and expenses that could have been
avoided.
Who’s job is it to prevent this type of situation? While it
is everyone’s responsibility, the general contractor must
take ownership. The problem is that the modern-day
construction method of design-bid-build is fragmented.
All the participants are specialists focusing on a single
task, unaware of how their work impacts the building as
a whole. In fact, the contract documents intentionally
silo the individual disciplines and then isolate the lines of
communication. The general contractor is obligated to the
owner to produce a building that meets the contractual
agreement. Ultimately, coordination between the various
trades as well as verification that the project outlined in
contract documents is constructible are the responsibility
of the general contractor.
One would say, therefore, that the general contractor, in
the situation described, should have done a better job,