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Risk Mitigation and Loss Control Using Electronic Leak Detection

August 17, 2023

IIBEC Interface August 2023
Feature
Interface articles may cite trade, brand,
or product names to specify or describe
adequately materials, experimental
procedures, and/or equipment. In no
case does such identification imply
recommendation or endorsement by the
International Institute of Building Enclosure
Consultants (IIBEC).
Risk Mitigation and Loss
Control Using Electronic
Leak Detection
By David Vokey, PEng, and Shaun Katz, CSI
SOME EXPERTS ESTIMATE that 75% to
80% of all construction-defect disputes are
related to roof failures, and that more than
70% of construction litigation involves water
intrusion.1,2 These issues are particularly
concerning for low-slope roof systems, which
are typically installed on large commercial and
residential buildings. Even the most carefully
constructed roof systems can suffer damage,
which often leads to water penetration into
the building interior. The costs associated
with the roof repair can be significant, and
water damage to the contents in the building,
particularly if it involves priceless artifacts
or expensive critical equipment, can be
staggering.3,4
There are several reasons that a roof system
can leak. These include:
• Design: Errors and omissions; conflicting
codes and guidelines
• Execution: Poor contractor quality of work,
inadequate training, and lack of quality control
• Materials: Sequencing, storage, and
manufacturer quality control errors
• Maintenance: Operating deficiencies,
maintenance oversights, and gaps in technical
knowledge
• Natural events: Heavy rain, hail, and snow
Historically, flood testing (Fig. 1) was the
traditional method of testing the integrity of
a roofing membrane.5 Over 25 years ago, an
international standard (ASTM D59576) was
developed to provide a guide for flood testing
horizontal waterproofing installations. While
providing some assurance of watertightness,
this type of testing is often difficult to perform
and should only be used on waterproofing
membranes that are installed directly on top
of a structural deck. Membrane breaches that
allow water to reach the deck but do not leak past
the deck will not be detected by flood testing.
However, that type of membrane breach could
become a leakage problem during the service
life of the roof system.
The National Roofing Contractors
Association7,8 and Canadian Roofing Contractors
Association9 do not recommend flood testing
of conventional low-slope roofs because there
is a risk of structural failure due to the weight
of water required. The Canadian Roofing
Contractors Association also states that flood
testing a roofing membrane is not a reliable
quality assurance method and that the risks
associated with flood testing far outweigh any
potential benefits.
During the last few decades, several methods
of detecting potential leaks in roofing and
waterproofing membranes using electronic
testing equipment commonly referred to as
“electronic leak detection” (ELD) have rapidly
been gaining acceptance.5,10,11 The four methods
used for locating membrane breaches are
described in the ASTM D7877, Standard Guide
for Electronic Methods for Detecting and Locating
Leaks in Waterproof Membranes.12 These four
ELD methods are low-voltage scanning platform,
low-voltage vertical roller, low-voltage vector
mapping, and high-voltage ELD (also known as
spark/holiday testing).
The four ELD testing methods operate using
the same physics and basic requirements. For
valid testing in new construction, each ELD
method requires the following:
• A conductive substrate directly under the
membrane to serve as a ground return path
for the test currents. Conductive substrates
are structural concrete, metal, or a conductive
medium designed to facilitate testing.
• A ground connection to the conductive
substrate. Typical ground connections include
metallic penetrations in direct contact with the
conductive substrate.
• An exposed membrane. The principle of ELD
is the establishment of an electrical potential
Figure 1. Flood testing a roofing membrane.
August 2023 IIBEC Interface • 19
between the membrane and underlying
conductive substrate. Electrically insulating
layers above the membrane interrupt any
electrical path/leak-locating signal.
• An electrical path from the surface of the
membrane to the conductive substrate.
Low-voltage ELD methods wet the surface of
the membrane. Water used during the test
carries the electrical current to the conductive
substrate. High-voltage ELD requires a dry
testing area and a direct vertical air gap
for the electrical path to travel through the
membrane to the conductive substrate.
While all four ELD methods employ the same
science (Fig. 5), they have different testing
procedures and limitations.
THE FOUR ELD METHODS
FROM ASTM D7877
Low-Voltage Scanning Platform
and Vertical Roller
The low-voltage scanning platform and lowvoltage
vertical roller units were created in the
early 2000s to simplify the ELD testing process.
Both the platform and roller are included in a
kit. These methods were designed specifically
for quality control testing of roofing and
waterproofing membranes.
In 2017, the scanning platform was modified
to “drown out” the conductivity of a membrane,
enabling the ability to test semiconductive
membranes such as black ethylene propylene
diene terpolymer (EPDM). This new ability
and technical advancement are reflected in
ASTM D8231-19, Standard Practice for the Use
of a Low Voltage Electronic Scanning System for
Detecting and Locating Breaches in Roofing and
Waterproofing Membranes,13 which provides
a more detailed description of both units.
Additionally, in 2022, the platform and roller
became the first and only FM-approved ELD
methods (Fig. 2).14
To test horizontal surfaces, the area is wetted
down. The scanning platform applies a lowvoltage
electrical current to the wet membrane.
For vertical surfaces, the roller sensor is moistened
and applied to the surface of the membrane.
The electrical current flows from the equipment,
through the water to the conductive substrate
below, resulting in an audible and visual alert.
The primary limitation of the low-voltage
scanning platform is that it only works on a
horizontal surface, and the surface must be wet.
Excessive water on the membrane may cause a
false positive if the water has a continuous path
from the platform to an electrically grounded
penetration such as a drain.
The roller attachment is used on
nonconductive areas where the scanning platform
cannot be used (such as transitions and verticals).
Excessive water from the moistened sensor to a
grounded object may cause the equipment to
alarm.
Low-Voltage Vector Mapping
Electric field vector mapping (Fig. 3) was
created in Germany in the 1970s. This method
was originally developed to test pond liners
and geomembranes. This method was later
adapted for use on nonconductive roofing and
waterproofing membranes.
The low-voltage vector mapping method
requires a perimeter wire (also known as
conductor cable) loop to be installed around
the perimeter of an area to be tested. Metal
penetrations and drains must also be isolated by
looping a separate cable around them and then
connecting these isolating cables to the main
perimeter wire. The membrane area within the
perimeter wire must have a continuous layer of
water. A generator is connected to the perimeter
wire, charging the area with up to 40 volts. A pair
of handheld probes are used to track the leakage
current to the breach.
There are some limitations with vector
mapping. Vector mapping method requires a
continuous layer of water on the membrane
within the perimeter wire, and any gaps in the
water coverage can result in missed breaches.
On new membranes, water tends to bead and
pool, which can often impede the formation of
a continuous water path. Some vector mapping
testing agencies will mix dish soap with the
water to assist with creating the required
continuous film, but this approach can cause
safety concerns.
Compared with the other ELD methods,
vector mapping has a lengthy setup process.
This is the only method in which the testing
area and all grounded objects must be
isolated before testing is performed. This
isolation area also eliminates the ability to test
critical areas such as transitions and details.
Testing verticals is also challenging and is
Figure 2. Low-voltage scanning platform (left) and roller (right). Figure 3. Low-voltage vector mapping.
20 • IIBEC Interface August 2023
not something that is recommended by the
equipment manufacturer.15 Most ELD testing
agencies use either high-voltage ELD or the
low-voltage vertical roller for testing verticals.
Vector mapping cannot test semiconductive
membranes such as black EPDM.
Some ELD testing agencies that use vector
mapping claim that it can be used to test through
overburden. Additional layers such as insulation,
drain mats, and root barriers can interrupt the
leak-locating signal because these layers are
electrically insulating and block the tips of the
probes from contacting the actual membrane.16
The presence of the left-in-place perimeter wire
does not guarantee future successful testing with
overburden.17,18
The vector mapping equipment manufacturer
in the United Kingdom does not support the
claim of testing through overburden, but some
ELD testing agencies continue to promote its
use. While the equipment might be used as
a troubleshooting feature, it is important that
expectations are managed and that all parties
should be made aware of the requirements and
limitations of testing through overburden.
High-Voltage ELD
High-voltage ELD (Fig. 4), also known as spark/
holiday testing, was created in Europe in the
1960s. This method was originally used for
locating breaches in coatings on pipes and later
adapted for testing roofing and waterproofing
membranes.
High-voltage testing is performed on a dry,
nonconductive horizontal or vertical surface,
and uses up to 40,000 volts. This method uses
either a broom or brush electrode apparatus
made of conductive metal bristles. The unit
is swept over the surface of the membrane.
At the location of a breach, an electric arc will
jump from the electrode. The arc requires a
direct vertical air gap to spark. Because of this
requirement, seam void detection is more
suitable with low-voltage ELD.
The most notable limitation of highvoltage
ELD is that the testing can only be
performed on a dry membrane surface. Any
moisture on the membrane such as dew or
frost will cause the equipment to alarm (a false
positive). This method is also not capable of
testing semiconductive membranes such as
black EPDM. Additionally, excessive voltage
can cause damage to the membrane if the
equipment is not calibrated for the correct mil
thickness. It is suggested that this equipment
should not be used in combustible areas as it
could result in an explosion; also, individuals
with electronic implants should avoid using
this method.16
Figure 4. High-voltage spark/holiday testing.
Detecting and repairing membrane
breaches (Fig. 6) during construction is
critical for the long-term viability of the
roofing system. ELD locates breaches in
the membrane during construction and
for the life of the building. ELD can be
performed on nearly all membranes,
including thermoplastic olefin membrane
(TPO), polyvinyl chloride (PVC), EPDM,
styrene-butadiene-styrene (SBS) modified
bitumen, hot fluid waterproofing, and cold
fluid waterproofing coatings, traffic coatings,
high-density polyethylene (HDPE) liners, and
geomembranes.
CONDUCTIVE MEDIUM
ELD requires a conductive substrate directly
below the membrane for a valid test; therefore,
some assemblies require the addition of
a conductive medium to enable testing.
Nonconductive substrates such as cover board,
insulation, wood, or lightweight insulating
concrete require this specially developed
conductive medium to provide the return path
for the test currents. Conductive media come
in numerous forms, such as an electrically
conductive primer or metal grid (Fig. 7). The
sole purpose of these products is to create
the required conductivity directly below
the membrane to enable valid and reliable
ELD quality control testing. Placement of a
conductive medium below cover board or
insulation will interrupt the electrical path,
resulting in an invalid test.19,20
The conductive medium used should
comply with appropriate building codes and
industry standards such as the Florida Building
Code, ASTM, UL listings, or FM Approvals. The
membrane manufacturer and type of assembly
(for example, adhered, fastened, torched) will
determine which conductive medium can
be used.
CONTINUOUSLY MONITORED
SYSTEMS
ELD has further evolved in the form of
embedded roof-monitoring systems. These
systems are installed in the roof assembly
August 2023 IIBEC Interface • 21
during construction and are often specified
for critical roof structures on facilities such
as hospitals, data centers, and museums.
Monitored systems can include sensors
arranged in a grid array (typically 15 × 15 ft
[4.6 × 4.6 m]) to form leak detection zones
(Fig. 8).
Monitoring systems provide continuous
status of the watertightness of the roof system
and will alert the responsible personnel of any
developing moisture-related problems (Fig. 9).
Because a monitoring system can detect
potential moisture problems long before
significant wetting of the roofing components
occurs, prompt corrective action can be taken,
thereby avoiding costly property damage.
To monitor a conventional roof,
temperature and humidity sensors can be
placed strategically in the assembly. The
monitoring software will then automatically
calculate the potential for condensation within
the roof assembly and within each zone. The
monitored system detects any areas where
moisture is located, typically at the vapor
barrier or vapor retarder, and provides a time
frame. Once moisture is detected, the building
owner can take action to determine the source
of moisture intrusion and arrange for removal
of moisture from the assembly.
In July 2022, FM Approvals updated
standard FM 774514.21 to include requirements
for products designed to prevent and mitigate
potential damage due to roof leaks. This
document requires that products and services
meet specific performance conditions ensuring
consistency and reliability to assist with risk
mitigation and loss control.
SUMMARY
Leaks occur. With the advent of ELD, valid and
reliable quality control testing and monitoring
can be performed to locate breaches, holes, and Figure 5. Electronic leak detection comparison chart.
Note: Membrane testing prior to installation of inverted roof components or overburden.
Figure 6. A breach is located and repaired.
22 • IIBEC Interface August 2023
seam voids. While each ELD method has its pros
and cons, the key to successful ELD is ensuring
that valid testing is part of the commissioning
process. Best practice is to perform ELD in new
construction on exposed membranes, which
provides a valuable option for risk mitigation and
loss control.
ELD quality control testing and continuously
monitored systems provide real-time data,
analytics, and insight required to help maintain
the health of the roof. This advanced technology
is critical to realize both the environmental
performance and design life of the roof while
avoiding preventable losses caused by roof
failures and moisture damage.
REFERENCES
1 Seward, A. 2011. “When It Leaks It Pours.” Architect.
https://www.architectmagazine.com/technology/
when-it-leaks-it-pours_o.
2 Hoch, J. 2016. “Water Intrusion Is the Largest
Generator of CDL Claims and Insurance Losses” (Tech
Alert blog post). QualityBuilt. https://www.qualitybuilt.
com/resources/tech-alert-water-intrusion-isthe-
largest-generator-of-cdl-claims-and-insurancelosses.
3 Benoy, D. D., P. Jergenson, and G. C. Patrick.
2020. “Low-Slope Roofs Are Rotting: Case Study
Resolution.” IIBEC Interface (January): 25–34.
4 Patterson, S. L., and M. Mehta. 2018, “Roof
Drainage Design, Roof Collapses, and the Codes.” In:
Proceedings 33rd RCI International Convention and
Trade Show, March 2018, 121–131. https://iibec.org/
wp-content/uploads/2018-cts-patterson-mehta.pdf.
5 Smith, T. L. 1995. “Flood Testing Roof Systems.”
Professional Roofing (February): 42. https://www.
nrca.net/Technical/PDF?id=65374&k=449903.
6 ASTM International. 1998. Standard Guide for Flood
Testing Horizontal Waterproofing Installations.
ASTM D5957-98. West Conshohocken, PA: ASTM
International.
7 Wilen, J. P. 2012. “The Art and Science of Electronic
Leak Detection.” Professional Roofing (November):
24–29. https://www.professionalroofing.net/
Articles/The-art-and-science-of-electronic-leakdetection–
11-01-2012/2170.
8 Crowe, J. P. 2006. “Water, Water Everywhere.”
Professional Roofing (February). https://www.
professionalroofing.net/Articles/Water-watereverywhere–
02-01-2006/800.
9 Canadian Roofing Contractors Association.
2009. “Bulletin: Flood Testing.” Roofing Canada
(November). https://roofingcanada.com/bulletin/
flood-testing.
10 IIBEC. 2021. Technical Advisory: Electronic Leak
Detection. IIBEC-TA-018-2019 (updated 2021).
https://iibec.org/publication-post/iibec-technicaladvisory-
no-018-2019-electronic-leak-detection.
11 Western States Roofing Contractors Association
(WSRCA). 2021. A Guide for Electronic Leak Detection
of Roofing and Waterproofing Membranes. Technical
Bulletin No. 2021-WC1. Morgan Hill, CA: WSRCA.
12 ASTM International. 2014, Standard Guide for
Electronic Methods for Detecting and Locating Leaks
in Waterproof Membranes. ASTM D7877-14. West
Conshohocken, PA: ASTM International.
13 ASTM International. 2019, Standard Practice for the
Use of a Low Voltage Electronic Scanning System
for Detecting and Locating Breaches in Roofing and
Waterproofing Membranes. ASTM D8231-19. West
Conshohocken, PA: ASTM International.
14 FM Approvals. 2021. Examination Standard for Liquid
Leak Detectors. FM Approval Class 7745. Norwood,
MA: FM Approvals.
15 Hoverman, C. 2021. “Roof Leak Detection
Inspection” (webinar). LDM Buckleys. https://youtu.
be/FhV2G3oKpXwm.
Figure 8. Moisture detection sensors being installed on a vapor barrier and a vapor retarder.
Figure 7. Examples of conductive medium.
August 2023 IIBEC Interface • 23
Figure 9. Moisture
detection sensors (before
roofing is completed) and a
monitoring center.
16 “Electronic Leak Detection High vs Low Voltage.”
Waterproof! Magazine. October 13, 2013. https://www.
waterproofmag.com/2013/10/electronic-leak-detectionhigh-
vs-low-voltage.
17 Brooks, P. 2017. “Electronic Leak Detection: Sound Science,
Not a Magic Wand.” RCI Interface (July): 20–24. https://
iibec.org/wp-content/uploads/2017-07-brooks-2.pdf.
18 Sika Corp. 2015. “Electronic Leak Detection Testing
Limitations.” Technical Bulletin 15-8 (August 11, 2015).
https://usa.sika.com/dms/getdocument.get/74f5300ef397-
4850-96d5-cd063ef213ee/15-8-eld-testing-limitations.
pdf.
19 Baskaran, B., and D. Lefebvre. 2019. “Good Codes vs.
Durable Roofs—Which Is the Missing Link? Where Is
the Sweet Spot?”: Presented at the RCI International
Convention, Orlando, FL, March 17, 2019.
20 Sika Corp. 2017. “Electronic Leak Detection Testing on
Roofing Projects.” Technical Bulletin 17-09 (August
2, 2017). https://usa.sika.com/dms/getdocument.
get/3f21a134-bdf5-47ee-aed8-684a8fb422a1/ELDTesting-
Limitations-15-8.pdf.
21 FM Approvals. 2022. “Updated Standard: FM 7745, Liquid
Leak Detection” (news release, July 18, 2002). https://www.
fmapprovals.com/product-alerts-and-news-events/news/
updated-standard-fm-7745.
ABOUT THE AUTHORS
DAVID VOKEY, PEng
David Vokey, PEng, is a
founder, president, and CEO
of Detec Systems. He
graduated from the
University of Manitoba with a
bachelor of science in
electrical engineering in
1973 and master of
engineering from the
University of Manitoba in
1984. Prior to co-founding
Detec Systems, he worked for Siecor Corp. (now
Corning Cable Systems) as the manager of R&D for
cable development, responsible for the design and
development of fiber optic cables. He holds over 40
patents worldwide relating to fiber optic cables and
moisture detection in building envelopes. He is a
member of IEEE, IIBEC, ASTM, and the Association of
Professional Engineers and Geoscientists in both
British Columbia and Manitoba.
SHAUN KATZ, CSI
Shaun Katz,CSI, has over
20 years of experience in
customer service and
business administration. He
has assisted contractors,
architects, engineers and
consultants, manufacturers,
facility/property managers,
and building owners with
forensic leak investigation, as
well as leak detection in new
construction. He is a member of IIBEC and CSI.