Waterproofing Design and Construction Coordination and Sequencing

Waterproofing Design and Construction
Coordination and Sequencing
Jerry L. Abendroth, RRC, RWC, RRO, CDT; and
Matthew R. McElvogue, RWC, PE
Building Exterior Solutions, LLC
6975 Portwest Drive, Ste. 100, Houston, TX 77024
Phone: 713-467-9840 • Fax: 713-467-9845 • E-mail: jabendroth@besgrp.com and mmcelvogue@besgrp.com
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Abstract
In designing waterproofing solutions, architects and waterproofing consultants often
introduce problems with interfacing systems. Failure to plan for these conditions prior to
preparation of bid documents and to coordinate with contractors early in the construction
process can create significant issues with budgets and schedules and adversely affect the
performance of the systems. Broad issues, specific conditions, and case studies related to
some of these challenges will be presented. Waterproofing consultants, architects, and engineers,
as well as building owners with intermediate-to-advanced waterproofing knowledge
and experience will come away with an increased awareness of avoidable waterproofing
design and construction pitfalls.
Speakers
Jerry L. Abendroth, RRC, RWC, RRO, CDT — Building Exterior Solutions, LLC – Houston, TX
Throughout his 35-year career, Jerry Abend roth has managed waterproofing and
roofing projects on a diverse portfolio of buildings in a variety of roles in the construction
and consulting fields. He has performed design peer reviews of building envelopes, as well
as building envelope commissioning for many commercial, medical, and industrial projects.
In addition, he has performed evaluations of building envelope system failures on projects
throughout the U.S. and provided associated repair recommendations and designs. His
experience resolving designs and construction-related issues has provided resolutions to
unique problems encountered with building roofing and waterproofing systems.
Matthew R. McElvogue, RWC, PE — Building Exterior Solutions, LLC – Houston, TX
For nearly half of his almost 20-year career in building engineering, Matth ew
McElvogu e has focused on building envelope investigation, remediation, water infiltration
mitigation, and forensics. His combined experience includes geotechnical investigation,
foundation design, structural design, and building envelope design and evaluation for new
construction, renovation, and restoration. This experience has provided McElvogue with
unique knowledge and understanding of proper construction and specification, poor detailing
and execution, and most points in between.
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PURPOSE A ND S COPE
Purpose of Paper
Although waterproofing methods and
materials have improved by leaps and
bounds in the past 50 years, the process by
which construction projects are developed
and managed has remained generally the
same. Some improvements have allowed
systems to be more forgiving; however, the
need to make solutions more cost-effective,
lighter, and more environmentally friendly
has actually increased the susceptibility of
below-grade waterproofing systems to failure.
In this paper, we will discuss a number
of conditions that should be considered and
coordinated during the predesign, design,
and construction phases of the project. We
will also discuss a number of special considerations
related specifically to remediation
of below-grade waterproofing systems
for existing construction.
Basics of Waterproofing/Scope of
Discussion
Before we discuss coordination issues in
more detail, we should review the definitions
of the systems we are discussing. According
to ASTM D1079-10, Standard Terminology
Related to Roofing and Waterproofing,
waterproofing is defined as “treatment of a
surface or structure to prevent the passage
of water under hydrostatic pressure.” Most
applications of these systems involve belowgrade
structures including building pits
(i.e., elevators and sumps), floors, walls,
and overhead horizontal surfaces, as well
as other structures such as underground
tanks and vessels. Applications may also
extend to components of structures such as
protection of piers, piles, footings, and other
structures.
Systems and products for these applications
include positive-side waterproofing,
which is defined by ASTM D1079 as “an
application wherein the waterproofing system
and source of hydrostatic pressure are
on the same side of the structural element.”
They also include negative-side waterproofing,
which is defined by ASTM D1079 as
“an application wherein the waterproofing
system and the source of hydrostatic pressure
are on opposite sides of the structural
element.” Typical positive-side waterproofing
products include hydrophobic (waterresisting)
systems such as asphaltic/organic-
based rubber and plastic fluid-applied
and sheet-good systems; and hydrophilic
(absorptive/swelling) systems such as bentonite
panels and sheets. Modern improvements
have resulted in significant development
in these systems, including several
“hybrid” products (combined hydrophobic
and hydrophilic sheets).
Also important are the documents used
to convey the designer’s intentions and—as
permitted by the relevant agreements—to
legally bind the parties in the project.
As previously mentioned, although significant
advancements have occurred in
construction technologies and in the systems
themselves, the project design and
delivery process has remained generally
the same. These instruments include but
are not necessarily limited to the following:
outline specifications, front-end documents,
technical specifications, drawings,
submittals, construction change directives,
change orders, mock-ups, test and inspection
reports, and closeout documents. Some
advancement in project design and delivery
such as building information management
(BIM) are occurring but has not significantly
impacted waterproofing to date. Although
project coordination may also occur in
the form of various face-to-face and teleconference/
web conference meetings, final
outcomes should be reflected in these documents
that represent the standard of care in
the construction industry.
PREDESIGN/PROJECT SCOPE
DEVELOPMENT
Before we can begin the design process,
we must have an understanding of the
project requirements. Although the concept
seems fairly simple and obvious, this step is
most often left out or only partially completed
by waterproofing consultants. To better
illustrate this issue, let’s consider buying a
car. Although the car sales representative
does not have to be told that the customer
is interested in buying an automobile, some
additional information is necessary such
as car, truck, or SUV; desired gas mileage;
how many passengers; and if the car will
be kept for a long time or just a few years
(i.e., purchase or lease). Depending on the
answers, the performance and price of the
automobile can vary significantly. Also,
factors such as reliability, service history,
and even manufacturer’s track record come
into play.
The same concept applies to waterproofing.
Depending on the answers to questions
like required service life, required maintenance,
degree of redundancy, chemical
resistivity, and movement capability, the
price and range of applicable products vary
greatly. Unfortunately, there are no current
standard instruments to capture this information;
however, tools such as Construction
Specifications Institute’s UniformatTM can
assist with organizing these project requirements
early in project development. One
of the biggest challenges is that “you don’t
know what you don’t know.” If the architect
or owner were insightful enough to recognize
the need to engage a waterproofing
consultant, he or she recognizes the importance
and/or complexity of the project,
but may not be aware of relevant quesions
that need to be addressed. In The Manual
of Below Grade Waterproofing, Justin
Henshell presents ten considerations he
refers to as a “Designer’s Checklist.”1 This
section presents some standard questions
that should be addressed, as well as recommendations
for identification of issues that
may be unique and project-specific.
Taking the time to educate architects
and owners with important considerations
such as the applicability, differences, and
limitations of waterproofing systems will go
a long way in improving the understanding
Waterproofing Design and Construction
Coordination and Sequencing
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and communication regarding the owner’s
needs, intentions, and limitations. This can
and will reduce conflicts later in the project
if cost reduction is required. Although clarifying
project conditions and requirements
during the project scope development phase
of the project (or “predesign”) is preferred,
these items can also be clarified during
project design or even construction phases.
However, delays in clarifying these conditions
may increase the complexity and cost
for resolving issues. For our purposes, we
will assume that these issues will be clarified
to the greatest extent possible during
predesign and confirmed later in the project
delivery process.
Existing Conditions
Before ground is even broken, issues
such as the properties of the soil and water
chemistry should be known.2 Coordinating
early in the project with the design team
and geotechnical consultant will allow relevant
testing and sampling to be performed
in conjunction with other planned testing.
These tests may include soil permeability,
advanced groundwater elevation measurement
and logging, and the presence
of contaminants such as certain organic
compounds that may adversely affect some
waterproofing materials. In the Houston,
TX, area, numerous below-ground pipelines,
tanks, and other hazardous materials
handling systems are present. Older
systems may not be properly documented
in the public record and, therefore, may
not be detected during Phase I environmental
studies. Required and/or recommended
below-grade soil and water testing
will depend, to some degree, on the final
system(s) specified. Discussions with product
manufacturers early in the process will
help the consultant determine the minimum
level of testing that should be performed.
Construction Methods and Schedule
The architect or owner may not be able
to answer questions such as, “Do we plan
to use blind-side waterproofing?” or, “Do
we need below-slab dewatering systems?”
However, they will likely be able to provide
statements such as, “We are limited in our
ability to excavate on the west side and will
have to cast the wall directly on the soil or
stabilization,” or, “Given the time of year for
construction, we plan to slope the subgrade
to the exterior and use granular fill directly
below the floor slab.” This type of information
will help the consultant
to make determinations
regarding
the applicability of
various systems and
should serve as documented
basis for product
selections. If the
assumptions change,
so may the specified
systems. Other factors
that can significantly
impact the type
of system(s) specified
include the length of
time the waterproofing
systems will be
exposed to sunlight;
the type and degree
of foot or machine traffic to which the systems
will be exposed; location, frequency,
and type of construction joints; ambient
temperatures during construction of waterproofing
systems; use of admixtures or
curing compounds; and compatability with
adjoining systems.
Quality Assurance and Quality Control
Quality assurance and quality control
are two related concepts that are often
used interchangeably; however, the scope,
strategies, and tactics associated with each
are very different. This confusion is exacerbated
by the lack of uniformity among
generally accepted standards. According
to the American Society for Quality
(ASQ)—a trade organization often associated
with the International Organization for
Standardization (ISO)—quality assurance
is defined as “the planned and systematic
activities implemented in a quality system
so that quality requirements for a product
or service will be fulfilled.”3 This term is
often confused with quality control, which
is defined by ASQ as “the observation techniques
and activities used to fulfill requirements
for quality.”4 Although the general
duty of quality assurance typically falls to
the general contractor, quality control is
generally fulfilled by the subcontractor performing
the work, but it may be assigned to
an independent agency or the waterproofing
consultant. Quality control varies greatly
from the periodic observations that are typically
defined in the waterproofing consultant’s
scope of services.
However, according to the Asphalt Roofing
Manufacturers Association (ARMA)
and National Roofing Contractors Association’s
(NCRA) “Quality Control Guidelines
for the Application of Polymer-Modified
Bitumen Roofing,”5 a slightly different set
of concepts is used. Here, quality control is
still discussed as being the responsibility
of the roofing contractor (subcontractor);
however, the duties associated with quality
assurance are stated as being the responsibility
of the building owner’s representative
(architect, engineer, or consultant) or the
manufacturer’s representative.
It is not necessarily critical that the
project team develop completely uniform
definitions for these concepts. However, the
team should clearly understand the differences
between concepts, how they relate to
the project, who is responsible for each, and
the specific tasks and deliverables related
to each.
Tolerance for Infiltration and
Performance Envelope
This may sound like a strange concept,
as we specify waterproofing products to
prevent bulk water and water vapor infiltration
(Figure 1). However, not all projects
are created equal. For example, one building
may have a single-level basement that
consists solely of mechanical equipment
with numerous floor drains, while another
building may have several below-grade levels
housing sensitive research or medical
equipment. Although both systems require
waterproofing for their below-grade construction,
the impact of some water infiltration
varies greatly for these two buildings.
Following a recent hurricane, we were
asked to evaluate the basement-level water-
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Figure 1 – Evidence of minor water infiltration at a column.
proofing for a museum of art. On the basement
level, millions of dollars of artwork
were being stored, and the question was
asked, “Under what conditions could waterproof
integrity of the system be assured?”
In this case, the waterproofing systems and
redundant drain systems could perform to
a reasonable degree, provided power was
available and for limited times without
power (due to capabilities of backup generators
and fuel stores); but if power failure
occurred, water infiltration could build to
unacceptable levels within several hours,
and the floor slab could breach under
hydrostatic pressure. Therefore, regular
storm conditions were considered acceptable,
but hurricane conditions were not.
A determination was made to develop contingency
plans to move the artwork in the
event of a hurricane.
Vapor transmission can also present
challenges in certain situations. Sensitive
flooring materials may be susceptible to failure
if vapor transmission through concrete
exceeds certain limits. Additionally, the
presence of special-use conditions such as
certain surgical suites and computer data
centers with critical temperature controls
can exacerbate condensation with excessive
vapor transmission. Flooring system
manufacturers are generally aware of these
conditions and have requirements or procedures
in place to ensure the substrates are
acceptable for their products. However, for
various reasons, these issues are occasionally
not properly addressed; and significant
problems—including damage to finish materials
and significant disruption of operations—
may ensue. Therefore, the consultant
should ensure that the general contractor,
waterproofing and finish subcontractors,
and relevant manufacturers are well
coordinated, and that resulting plans are
in place and are being properly executed.
ASTM F710, Standard Practice for Preparing
Concrete Floors to Receive Resilient Flooring,
should be part of the process.
Redundancy and Water Management
In cases where even small amounts of
water and/or vapor transmission through a
system cannot be tolerated, redundant (or
backup) systems may be employed. Rarely
do we see the need for these systems in new
construction, given the ability to achieve
superior performance with today’s waterproofing
systems and diligent quality assurance
and quality control. However, redundancy
can often be employed for waterproofing
remediation of existing structures.
Often, negative-side waterproofing with targeted
chemical injection is employed for
existing below-grade waterproofing systems,
given the relatively low cost of construction
compared to excavation and application of
positive-side systems for walls. However,
these systems generally do not provide for
“complete” waterproofing in that some limited
water infiltration occurs under certain
conditions. Recognizing this potential and
providing means for directing this ancillary
water away from finished construction can
be effective (Figure 2). There are special considerations
for water management systems
such as required maintenance to reduce
odor, fungal growth, and build-up of salts.
Chapter 6 of The Manual of Below-Grade
Waterproofing Systems discusses some of
these considerations in more detail.6
In considering
basement waterproofing
options for an
existing medical facility,
we recognized
that isolated areas
of water infiltration
historically occurred
at specific locations
with more widespread
water infiltration during
periods of heavy
rainfall. Additionally,
we noted that numerous
joints and partial
floor repairs
were present in the
floor slab, which had
resulted in water infiltration
through the
floor slab. Negativeside
waterproofing of
the exterior walls was
employed as well as a
maintenance corridor
around the perimeter
of the exterior wall.
Additionally, we utilized
a new floor slab
over uniformly graded
fill, with an integral
drainage system and
blind-side waterproofing
below the new
floor slab to manage
water infiltration from
the floor-to-wall interface
and through the exterior wall itself
(Figure 3). Floor drains in the maintenance
corridor were also incorporated to direct
ancillary water infiltration into the basement
drainage system. Other less extensive
measures such as gutters below expansion
joints and curbs at known locations of
isolated water infiltration may also prove
effective in providing redundancy and water
management.
These systems provide significant benefits,
often at very reasonable cost; and
in the case of the maintenance corridor,
they can also provide the added benefit of
facilitating utility runs. Significant coordination
is required with the design team to
determine where these runs will occur and
where interfaces between the utilities and
waterproofing systems will occur. Since
significant change often occurs in the exact
placement of piping, conduit, and other
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Figure 2 – Gutter below expansion joint.
Figure 3 – Drainage system below maintenance corridor.
utility components, constant monitoring
and coordination are required during the
construction phase of the project to ensure
waterproof integrity is maintained throughout
project delivery.
Service Conditions and Service Life
The performance of a waterproofing system
may depend on what it is doing. For
example, many waterproofing systems are
susceptible to deterioration from groundwater
contaminants. If systems are well
drained and sources of contamination are
not present, these systems will likely have
good service lives. But if drainage systems
fail and contaminants are present or new
sources of contaminants emerge, the waterproofing
system may be compromised and
experience early failure. If the owner knows
that an adjacent property may be developed
for an industrial coatings manufacturer,
it may be prudent to select a system with
more robust resistance to the types of contaminants
resulting from this future change
in service conditions.
No systems are designed to last forever,
and even systems with outstanding
overall service lives experience variations
in their levels of service. Also important is
understanding what “service life” means
for the system. For example, certain types
of coatings can be recoated at the end of
their regular service lives to extend the
lives up to twice their original service lives;
but after recoating once, the entire system
will require removal prior to installation of
a third application. Urethane and silicone
coatings typically fall into this class of coatings.
On the other hand, some tank and
swimming pool coatings can be reapplied
numerous times without full removal. These
include various cementitious, crystalline,
and epoxy coating systems.
Construction and Life Cycle Costs
Too often, waterproofing consultants
make the leap to construction costs early
in the project development coordination
process without first understanding the
owner’s requirements. This typically has an
adverse effect in communicating with the
waterproofing consultant’s client in that
both parties begin to filter thoughts and
considerations with regard to performance
based on stated cost parameters. If the client’s
wants and needs as reflected in his or
her documented performance requirements
do not appear to line up with the anticipated
costs of the systems, then productive discussions
can take place to redevelop stated
requirements. Consultants should also take
care to review alternative systems with their
clients, even if they are somewhat below or
above their stated acceptable cost. In some
instances, the client may not be aware of
the benefits of certain systems, such as
available special warranties or hybrid systems
that can reduce risk and maintenance
or potentially reduce cost while still providing
a reasonable level of service and life
cycle cost.
The cost components should also be
clarified with the waterproofing consultant’s
client. It is important that the owners clarify
their needs with regard to additional costs
such as follow-up inspections and maintenance,
anticipated partial replacements or
“recoating,” and other soft costs and general
conditions, including building access and
loss of use. Only with this complete picture
can the waterproofing consultant make
truly informed recommendations.
Warranties
According to the collective wisdom of
Wikipedia, for business and legal transactions,
a warranty is defined as “an assurance
by one party to the other party that
specific facts or conditions are true or will
happen; the other party is permitted to rely
on that assurance and seek some type of
remedy if it is not true or followed.”7 First,
a warranty is only as good as the business
behind it. Construction documents should
require specific disclosure from bidding
contractors regarding their experience performing
similar work, including projects
similar in scope and size. References submitted
for this purpose should be contacted
to determine if the contractor has properly
represented his or her experience.
Next, knowing exactly what is covered
by a particular warranty is important.
Requirements for warranties should
be clearly noted in project documents,
but should be specifically reviewed with
system manufacturers to ensure they can
comply with the warranty requirements.
Several common types of warranties include
materials, labor, and no-dollar-limit (NDL)
warranties. Special warranties can often
be issued for unique needs or conditions
such as extended times or special service
conditions. Care should be exercised to
ensure that warranty language is reviewed
early in the project delivery process in the
form of specimens or samples and that
any additional requirements such as fees,
special inspections, or special requirements
such as recoating are clearly understood
by all affected parties. However, it should
be noted that provision of warranties in the
project documents in no way relieves the
owner from good system selection or relieves
the project team from sound design and
system delivery. Warranties are a very complex
legal topic; however, The Construction
Waterproofing Handbook provides some
sound discussion related to specific warranty
types, considerations, clauses, and
other provisions, with a focus on building
waterproofing.8
PROJECT DESIGN AND
CONSTRUCTION PHASES
As previously noted, clarification of
design parameters and coordination with
other designers and trades should happen
as early in the project development process
as possible. However, some issues such as
identification of utility-to-building interfaces
may not be adequately developed to facilitate
this coordination until the design, submittal
review, or even actual construction
phases of the project. Waterproofing consultants
should not consider an architect’s or
design consultant’s unwillingness to cooperate
with needed coordination or to “do it
the way I normally do” in the same manner
as necessary development required for basis
of coordination and design. Requests for
documents and other information should
be put in writing for the waterproofing
consultant’s client to ensure the request
is properly conveyed to the relevant party
and to ensure that proper “paper trails” are
present. These trails can come in handy
later in the project when change orders and
resulting disputes occur.
Even after receiving information in the
predesign or design process, this information
should be reviewed during each step of
the project design and delivery. Statements
by the architect and/or owner should be
reflected in the design documents; requests
for information or architects’ and engineers’
(AE) supplemental instructions; in the submittals;
and in submittal reviews, approvals,
and delivered work. Special care and
consideration should be given for projects
where “loose” clarification and supplemental
instructions occur. Although waterproofing
consultants understand that their instructions
are to be conveyed in the proper
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instruments, they need to be aware of other
methods of communication and instruction
that are essentially approved for the project.
In other words, just because information is
presented in an e-mail does not mean that
it can be disregarded because it is not in a
standard construction document.
Discussions With Waterproofing System
Manufacturers
Product manufacturers are one of the
greatest sources of information and assistance
to waterproofing consultants; however,
they are generally underutilized. Prior
to developing design documents, the waterproofing
consultant should reach out to
waterproofing system manufacturers and
begin discussing the parameters of the
project. Good representatives of reputable
waterproofing systems will readily discuss
project needs, identify systems that may
meet the project requirements, and note differences
and limitations of the various systems.
We often find that quality manufacturer
representatives will refer us to other
systems and manufacturers if they cannot
efficiently meet project requirements.
Contractors who are qualified and experienced
in installing and maintaining systems
under consideration are important
to project delivery. Quality systems without
a sufficient base of quality installers
can result in unanticipated project costs,
unacceptable work, and project delays.
Also important is the presence of similar
projects with similar construction in the
same “region” as the subject project. In
the Construction Waterproofing Handbook,
Michael Kubal presents a number of specific
points for selection of waterproofing contractors
that should be considered in addition
to price.9 Manufacturers should be able
to provide a shortlist of contractors qualified
to deliver the project.
Types of construction, construction
materials, workforces, groundwater, and
climatic conditions can influence the success
of a system. Waterproofing consultants
need to be cautious about use of “proven”
systems that are not in the same general
area as the subject project. Research,
including following up on references provided
by waterproofing system manufacturers
and subcontractors, can provide insight
into undisclosed problems or glowing successes
that may influence acceptance of
a system or contractor. In The Manual
of Below-Grade Waterproofing Systems,
Justin Henshell provides
sound caution
and research points
related to this.
Structural Response
For new construction,
determination
of design structural
movement in terms of
settlement/consolidation,
shrinkage, creep,
deflection, thermal
changes, and seismic/
wind loading is
generally straightforward.
The waterproofing
consultant must
coordinate with the
structural engineer of record and architect of
record to determine what movements are to
be expected and where they will be resolved.
Waterproofing systems intended to provide
service over these joints must be capable of
providing required waterproof integrity while
accommodating these building movements.
Chapter 6 of the Construction Waterproofing
Handbook discusses and illustrates a number
of considerations related to expansion
joint design and presents a handful of
standard details for various joint geometries.
However, one of the more robust
libraries for waterproofing details is the
NRCA Roofing and Waterproofing Manual,
Fifth Edition.10 System manufacturers will
often develop similar details in conjunction
with their proprietary systems. It is always
a good idea to require details as part of the
submittal package.
For existing construction, determination
of building movements
is not quite
so simple. Review of
documents—including
original construction
documents and
building maintenance
records—can provide
insight into locations
where building movements
were anticipated,
as well as the
expected order of the
movement (Figure 4).
Additionally, observation
of existing construction
can reveal
locations where building
movements were not anticipated, yet
occurred. Often, conditions such as lines
of vertical cracks in concrete and masonry
wall systems, lines of spalled concrete and/
or masonry, and tensile stress and buckling
of metal flashings can evidence building
movement that requires accommodation.
Crack bridging is often more challenging
to determine, given the numerous factors
that can influence the presence of concrete
cracks. Even though cracks and breaches
in waterproofing systems can be far more
detrimental than insufficient application
thickness or inconsistent application, proper
identification and treatment are often
overlooked. Coordination with waterproofing
subcontractors and quality assurance
personnel is critical to ensure these conditions
are identified. One very useful tool
in this coordination is the construction
mock-up. By selecting an area of the struc-
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Figure 4 – Custom expansion joint replacement.
Figure 5 – Utility penetration at exterior wall.
ture with a variety of crack sizes that can
remain uncovered until the end of the project,
partial treatment of such cracks can
be performed. This allows workers to see
both the original crack size and geometry
as well as the treatment method employed.
“Calibration” of this type is instrumental for
successful project delivery and long-term
system performance.
Underground Utilities
As waterproofing consultants, we understand
that addressing interfaces between
below-grade utilities and waterproofing
systems is a critical part of our scope.
However, we often overlook aspects of these
interfaces that can prove problematic for
waterproof integrity. Numerous methods
exist for extending utilities through the wall
structure, such as pipe sleeves, formed/
cast-in-place, and flexible junctions (Figure
5). Factors such as spacing (horizontal and
vertical) between pipes and conduit, as
well as approach or interface angles, can
significantly complicate interface detailing.
Coordination—including shop drawings of
“bundled” utility interfaces at wall lines—
can improve results at these locations.
During a recent project, bundled electrical
service into the building required that
concrete-cased conduit pass through the
exterior wall of the building below-grade.
After study of this condition, we determined
that the original plan to simply cut an opening
in the exterior wall and run the duct
bank continuously through the opening
would not ensure waterproof integrity at
this location. The reason is that although
the concrete pour encasing the conduit
was to be continuous through the wall,
water infiltrating around the perimeter of
the conduit at any point along the exterior
of the duct bank could infiltrate the building.
The determination was made to cut
the wall, place the conduit, pour the wall
repair, and tie-in the individual ducts at
the wall interface prior to pouring the entire
casing (Figure 6). In this manner, water
infiltration around the conduit would be
mitigated. As this method of construction
varied from that typically performed for this
type of system, careful coordination with the
general contractor and utility engineers and
subcontractors was required to ensure that
plans were in place to facilitate the staged
construction of this interface.
In another recent project, the interface
between a drain service exit and the
exterior wall was in question. The geotechnical
consultant anticipated that several
inches of vertical structural movement
was expected, which could result in up to
twice that amount in differential movement
between the building and adjacent soil. To
accommodate this condition, a larger-diameter
pipe was sleeved through the exterior
wall and extended a
significant distance
away from the building.
This construction
would allow the building
waterproofing systems
to be effectively
tied into the sleeve,
allowing the drain piping
to move within the
larger sleeve while still
receiving the appropriate
link-seal at the
exterior side of the
sleeve. Coordination
with the mechanical
design team and
subcontractors was
required to ensure the adjacent pipe joints
could withstand the anticipated movement/
rotation and perform as required.
Site Dewatering and Soil Compaction
Although waterproofing systems are
inherently designed to resist hydrostatic
water pressure often throughout their service
life, construction conditions must be
controlled to ensure proper application
(Figure 7). This proves extremely critical
with most hydrophilic waterproofing systems
that rely on confinement pressure to
provide the “seals” required for system integrity.
Premature hydration of these systems
without confinement in place can result in
damage to the system. Coordination with
mechanical engineers, geotechnical engineers,
and general contractors early in the
process is important to ensure that engineering
and other drainage controls are in
place to remove or draw down below-grade
and surface water during critical phases
of the project. These types of controls can
range from very simple passive systems
such as sloping of subgrade soils and use
of gravity drainage systems to more complicated
draw-down wells.
It is important to understand the relationship
between ground and surface water
and required subgrade soil compaction.
Geotechnical engineers determine the type
and degree of compaction required for various
soils below the structure. Most measures
of compaction include density of the soil at
a given moisture content. Compaction above
or below the optimum moisture content can
prove under- or overeffective, both of which
can be unacceptable for a project. In addition
to maintaining proper moisture content
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Figure 6 – Section detail at duct bank penetration.
Figure 7 – Failure to properly drain subgrade.
during compaction, certain soil types can
lose compaction with the introduction of
water after compaction. Clear statements
and metrics regarding permissible water
and soil moisture conditions should be
provided by the geotechnical engineer as
well as remedial recompaction requirements
for “wet soils.” Provisions for site drainage
should be coordinated with the general
contractor to comply with the geotechnical
engineer’s recommendations to the greatest
extent feasible. Failure to properly plan
for site water conditions can result in significant
damage to and required replacement
of waterproofing work. Additionally,
administrative controls such as pour size/
construction area and drainage breaks during
construction can be developed to reduce
the potential impact from uncontrolled site
water. Contingency plans for recompaction
of wet soils should also be developed
to limit downtime due to these conditions.
American Concrete Institute (ACI) Standard
302, Guide for Concrete Floor and Slab
Construction, provides some specific considerations
regarding floor slab construction.
The U.S. Army Corps of Engineers offers
several standards regarding soil preparation
and drainage, primarily for roadways;
however, some of these approaches can be
applied to floor slab construction as well.
Concrete Curing and Form Release
Agents
Desired methods for curing concrete
slabs and walls are often determined early
in the design process, given the type of
construction, general site location, climatic
conditions, and time of year of construction.
Although proper concrete curing is critical
to ensure proper hydration of cementitious
materials and to prevent unwanted cracking
of walls and cracking and curling of slabs,
the methods and materials used for curing
concrete can pose challenges to waterproofing
products and certain finishes. Curing
compounds such as film-forming liquid
products are designed to retard evaporation
of water within the concrete. These
properties can also retard the development
of needed chemical and mechanical bonds
between positive-side waterproofing materials
and the concrete. On the negative side of
the structure, these compounds can block
pores within the concrete, which can reduce
the ability of crystalline waterproofing systems
to effectively migrate into the concrete.
Moisture curing of concrete is often preferred,
especially for
floor slabs on grade,
as it is generally economical
and effective
(Figure 8). The waterproofing
consultant
should understand
that the effect of curing
is to retain moisture
content within
the concrete to slow
the hydration process.
Therefore, depending
on the required curing
process, the time
at which the concrete
vapor transmission
will reduce to acceptable
levels for the
application of certain waterproofing products
will also vary. Coordination with the general
contractor, waterproofing contractor, quality
assurance personnel, and waterproofing
system manufacturer should be facilitated.
This coordination will help determine the
anticipated duration of concrete curing,
required surface cleaning or preparation,
and the manner in which the waterproofing
system manufacturer requirements for concrete
curing and vapor transmission testing
will be applied to the project. ASTM D5295,
Preparation of Concrete Surfaces for Adhered
(Bonded) Membrane Waterproofing Systems,
provides guidance for cleaning and preparation
of substrates to receive waterproofing
products, and the ACI 546 family of documents
specifies materials and methods for
addressing problematic concrete surfaces.
Form release agents are typically of one
of two categories of products: barrier types
and reactive types. Barrier-type agents typically
consist of oils, fuels, waxes, or other
hydrocarbons that prevent a bond from
developing between the hardened concrete
and the concrete form. Reactive agents
include a wide range of products that
interact with compounds in the concrete
such as calcium and lime, resulting in
conditions that prevent bond or actively
separate the hardened concrete from the
form. Coordination with the design team in
specifying form release agents with input
from waterproofing system manufacturers
can prevent significant labor costs associated
with excessive surface preparation
required to mitigate the effects of form
release agents. Waterproofing construction
mock-ups and adhesion testing at locations
where form release agents are used should
be specified in the construction documents
and coordinated with the general contractor,
waterproofing contractor, and concrete
subcontractor to ensure proper bond of
waterproofing system is achieved.
Expansion Joints and Unsupported
Waterproofing
Expansion joints are common in building
waterproofing systems and can be properly
designed with coordination among the
structural engineer of record and architect
of record as noted above. However,
sequencing of expansion joint construction
and interface with the waterproofing
components can be more challenging.
Often, seemingly good provisions such as
“prewelded” or “prefabricated” corners and
transitions are included in project specifications,
but consideration is not given in
the procurement process to the lead time
required for delivery of these products.
In several projects, consideration was not
given to the possible lead time required in
developing required submittals/shop drawings,
approval of submittals, and fabrication
of special components. These unplanned
delays can result in excessive exposure of
waterproofing construction and unwanted
change directives to convert prefabricated
elements to field-installed. Coordination
with the waterproofing contractor early in
the project delivery process can help him
or her understand which components may
have excessive lead times, and efforts can
then be undertaken to expedite critical path
steps to achieve their timely delivery.
Understanding schedule and sequence
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Figure 8 – Wet curing of concrete repairs in below-grade
concrete storage tank.
of construction and backfilling is important
in ensuring that expansion joints are delivered
as intended. In some cases, partial
backfills are required to facilitate some other
manner of the project, such as installation
of utility or perimeter drainage systems.
Waterproofing systems and expansion joints
should be properly constructed and terminated
prior to backfilling. However, certain
construction sequences may require partial
waterproofing installations and progressive
backfilling. This will require temporary tieins
and protection of waterproofing materials
at subsequent tie-in locations. These
conditions should be sufficiently detailed
and specified; however, special attention
and coordination should be facilitated to
ensure the general contractor, waterproofing
contractor, and other trades such as
landscaping contractors are aware of these
special conditions.
In a recent renovation project, two different
expansion joint types were required
between a concrete stem wall of a new
floor slab and an injection system below
the expansion joint of an existing floor slab
expansion joint. The interface between these
two systems consisted of a blind-side application
of chemical injection combined with
a positive-side application of a sheet-type
expansion joint system that transitioned
to a blind-side application at the new floor
slab. To make matters worse, these joints
and transitions occurred at a concrete column.
Coordination between the waterproofing
contractor and general contractor was
facilitated, and a staged mock-up was performed
at one joint condition (Figure 9). The
mock-up consisted of the installation of the
positive-side expansion
joint with partial
backfill and the blind
chemical injection of
the lower expansion
joint at the transition.
Prior to pouring the
new floor slab, the
backfill was carefully
pulled back to ensure
the desired bond or
interface between
the chemical injection
and expansion
joint was achieved.
Application of the
same proven methods
was then employed at
other joint locations.
On paper, bellows, flashings at laps, and
other smaller provisions for movement seem
like good practices. However, consideration
is often not given to support these elements.
When hydrostatic or soil surcharge
lateral loads are imposed on waterproofing
systems, these elements must have
proper substrate support to resist the loads.
Additionally, manufacturers often limit the
“free span” of flashings and sheet-good
systems based on systems testing. Too
often, waterproofing consultants rely on
statements in waterproofing drawings or
specifications such as “limit gap to 1 inch
or less.” However, trades such as concrete
subcontractors typically do not reference
these documents but refer to structural
documents and Division 3 specifications.
Therefore, waterproofing contractors
need to be familiar with these documents,
specifications, and related standards such
as ACI 117, Specification for Tolerances
for Concrete Construction and Materials.
Important waterproofing joint widths and
tolerances should be reviewed with relevant
design consultants and contractors
to ensure specification of these provisions
is coordinated throughout the design and
construction phase documents.
Submittals and Submittal Schedules
Submittals are instrumental for the
waterproofing consultant to confirm that
the relevant contractor(s) understand the
intent of the construction documents.
However, the degree of confirmation is limited
to the extent that the contractor preparing
the submittal denotes specific systems
to be used and indicates on drawings and
markups where systems are to be installed.
Again, technical specifications should enumerate
exactly what is to be conveyed on
project submittals. Too often, architects
and consultants approve very broad and
vague submittals, even when more detailed
documents are required by project specifications.
Consultants should understand that
this type of broad-brush approval typically
does is inconsistent with the consultant’s
standard of care. Often, brief phone calls
with the general contractor and/or his
subcontractor(s) to review technical specification
requirements can reduce the lack of
compliance and delays resulting from poor
submittals.
Another helpful instrument is the submittal
schedule. This document, which may
be incorporated into the project delivery
schedule, serves as a checklist and reminder
for submittals required by the construction
documents.
Proof of Concept/Test Repairs and
Mock-Ups
Throughout this paper, references have
been made to performing and testing of
mock-ups. In addition to developing mockups
to clearly establish acceptability standards
for delivered work, performing proofof-
concept mock-ups or test repairs prior
to developing design documents is important.
Particularly for remediation work,
these mock-ups provide insight into work
steps required to achieve desired outcomes.
In a recent plaza waterproofing remediation
project, we observed existing cladding,
weather barriers, concrete topping, and
waterproofing systems and presented conceptual
repair options. After coordinating
with the architect of record and landscape
architect, we provided drawings and specifications
for remedial waterproofing that most
adequately addressed the owner’s requirements.
Following construction of the repair
area, flood testing of the waterproofing and
interfaces was conducted in general conformance
with ASTM 5957, Standard Guide
for Flood Testing Horizontal Waterproofing
Installations, for 48 hours with regular
observation of the areas below (Figure 10).
Although several conditions required minor
modifications, the test proved the system
was successful.
As noted above, determination of mockup
locations, conditions to be constructed,
and required testing should be coordinated
with the general contractor early in the con-
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Figure 9 – Review of blind-side chemical injection mock-up.
struction phase. Although it should go without
saying, the mock-up construction and
successful testing of the mock-up should
precede delivery of work. This basic premise
often escapes general contractors and
subcontractors, and it should be confirmed
early in the process to help limit adverse
impacts to construction schedules or waivers
of mock-up construction by the architect
or owner. Mock-ups are one of our most
powerful tools as waterproofing consultants
and one of the most common aspects of
the project that are taken out due to cost
and time limitations. If mock-ups that were
agreed to earlier in the process are removed
by the architect or owner, the waterproofing
consultant should inform the architect or
owner in writing of this noncompliance, and
state consultant’s requirements (if any) for
execution of limitation of liability and of any
potential effects on system warranties.
The purpose of the construction mockup
is not only to clearly define construction
acceptance but also to test the constructability
of various interfaces. Construction
documents should clearly convey the components
to be incorporated into construction
mock-ups; however, early coordination
should be conducted with the general
contractor and waterproofing contractor
to identify in-place construction that may
serve as sound construction mock-ups.
Factors such as completion of work based
on construction schedule, time that area
can remain visible, and access to the mockup
should be considered.
Ingress and Egress
and Waterproofing
Protection
Coordination with
the general contractor
should be facilitated
to understand how
and where foot and
equipment traffic will
move across the site.
If pour sizes are reasonably
limited, the
amount of exposed
blind-side waterproofing
can also be limited.
This can help
mitigate the impact of
traffic on the waterproofing
systems. Traffic
areas should be clearly marked with
barricades, caution tape, or other means as
necessary to help direct foot and equipment
traffic away from installed waterproofing.
At locations where installed waterproofing
must be trafficked, clear pathways
should again be set up, and adequate
protection layers should be installed. For
trades such as concrete subcontractors who
are required to move across the entire area
when placing steel reinforcing and forms,
entrance and exit from the work area should
be directed through aprons consisting of
pads or sheets of sticky shoe-cleaning material
to reduce the amount of debris
trafficked onto the installed waterproofing.
Most blind-side waterproofing
sheet materials have protective layers
or films designed to protect the
waterproofing layers until the concrete
can be cast. Preconstruction meetings
should be specified in the construction
documents. In the meeting, a discussion
of how membranes will be protected
should be facilitated (Figure 11).
Typically, retaining these protective
layers until steel reinforcing is to be
tied will prove effective. However, typical
activities by concrete subcontractors
such as dropping bundles of reinforcing
and tools on the waterproofing
membrane can result in breaches in
the membrane. Preventive measures,
such as the use of wood dunnage to
bolster bundles of steel reinforcing
above the waterproofing, can improve
the protection of the waterproofing.
Inspection Milestones
During the preconstruction meeting
for the basement waterproofing and basement
structure, milestones at which critical
inspections must occur should be clearly
defined. These milestones may include
mock-up construction; completion of final
finishing of grade soils, drainage layers,
or excavations; completion of tieback or
retaining assembly construction; surface
preparation of substrates; pretreatment of
cracks and voids in concrete and masonry
systems; placement of cants and/or flashings;
interim coats or layers of waterproofing
materials; final coats or layers of
waterproofing materials; and installation of
insulation, drainage mats, and/or protection
boards. Frequency of inspection and
resolution of deficient construction should
also be discussed and coordinated with the
relevant trades.
Depending on the construction schedule,
backfill against basement structure
may follow completion of work in short
order. Although it is important that the
general contractor inform the project team
prior to backfilling, miscommunication or
lack of communication can result in failure
to do so. It is the waterproofing consultant’s
obligation to maintain frequent contact with
the general contractor during waterproofing
system construction to ensure work that
should be observed is not covered prior to
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Figure 10 – Flood test of partial plaza waterproofing
replacement.
Figure 11 – Failure to protect waterproof
sheet during adjacent concrete pour.
inspection. In some instances such as work
in confined spaces, extremely prompt or
immediate protection of work or backfilling
is necessary. These special cases should
be clearly identified; and, if necessary, the
waterproofing consultant should be on site,
standing by to observe construction as it is
completed.
Drains and Weeps
Some systems and assemblies employ
the use of drain and/or weep systems to
manage water, mitigate water levels and
hydrostatic pressure, or serve as redundant
systems. Coordination with the general contractor
and relevant subcontractors should
be performed to observe all drain locations
prior to covering work, including, but not
limited to, pouring of slabs and installation
of positive- or blind-side waterproofing.
Markups of as-built
conditions should be
made by the waterproofing
contractor;
and upon completion
of the work, the
waterproofing contractor
should again
observe the completed
construction to make
sure all of the drains/
weeps are visible and
open.
During a recent
basement level renovation
project, we visited
the site to observe
a unique field condition.
Prior to meeting
the contractor, we walked the site and
noted that the drains were not visible in
the sump pits, but we had noted clearly on
field notes and documented with photos the
locations of drain pipes entering the sump
pits. Following an “oops”-type statement,
the contractor slid down an access ladder
and began hammer-sounding the concrete
in the area where the drain should have
been located. He found a shallow area, and
when he pounded the concrete firmly with
the hammer, a half-full, 4-in.-diameter pipe
began draining rapidly into the sump pit
(Figure 12).
CLOSING
Numerous conditions throughout the
project delivery process require coordination
with a variety of design and construction
professionals as well as building owners
and their representatives. Through this
paper, we have presented concepts and
examples of waterproofing concerns and
considerations that will hopefully serve not
as a fixed checklist, but as a general work
process that will help waterproofing consultants
foresee and work through challenges
before they can become problems.
References
1. Justin Henshell, Manual of Below-
Grade Waterproofing Systems (John
Wiley & Sons, Inc., 2000), 61-65.
2. Ibid., 52-53.
3. “Quality Assurance and Quality
Control,” accessed August 31, 2012,
http://asq.org/learn-about-quality/
quality-assurance-quality-control/
overview/overview.html.
4. Ibid.
5. ARMA/NRCA, “Quality Control
Guidelines for the Application of
Polymer-Modified Bitumen Roofing,”
1996.
6. Henshell, 89-91.
7. “Wikipedia-Warranty,” accessed August
31, 2012, http://en.wikipedia.
org/wiki/Warranty.
8. Michael T. Kubal, Construction Waterproofing
Handbook, Second Edition,
(The McGraw Hill Companies, Inc.,
2008), 11.11-11.16.
9. Ibid., 11.1-11.9.
10. National Roof Contractor’s Association,
The NRCA Roofing and Waterproofing
Manual, Fifth Edition
(NRCA, 2001, 2003, 2006), Volume
4, 1454-1505.
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Figure 12 – Opening of concealed drain at sump pit.