The Leak Stops Here: Understanding the Methodology of Leak Detection for Roofing and Waterproofing Systems John Posenecker Terracon | Austin, TX John.Posenecker@Terracon.com Marcy Tyler Terracon | Austin, TX Marcy.Tyler@terracon.com Trevor Brown, Dante Marimpietri, and Keith Simon IIBEC International Convention & Trade Show | SeptembeBEr 15-20, 2021 P PoSEnECKEr et al | 89 90 | Poseneck er et al II BEC International Convention & Trade Show | September 15-20, 2021 ABSTRACT This intermediate-level presentation is intended for owners, designers, and contractors. Portions of the building enclosure’s water barrier subjected to hydrostatic water pressure must be waterproofed to prevent water infiltration. For the purposes of this presentation, waterproofing can be in the form of a roofing or waterproofing membrane. Roofing and waterproofing membranes need to be evaluated for continuity prior to the completion of original construction. This matter is of special concern if the application will be covered with a cladding system or overburden that makes access to the application difficult throughout the life of the building. This paper will take a deep dive into water testing and other available test methods, such as high-voltage and lowvoltage electronic leak detection, infrared testing, and electrical impedance testing. Testing does not replace visual observations during construction—it only confirms the initial performance of the membrane. A checklist of critical items to observe prior to, during, and after an installation will be discussed along with the recommended testing methodology. John Posenecker Terracon | Austin, TX John Posenecker joined Terracon in March 2015. A registered mechanical engineer, he is on the Building Enclosure Council (BEC) National Board and is a board member and Technical Committee cochair for the Air Barrier Association of America. His experience includes the design, construction, testing, and forensic investigation of building enclosure systems. Posenecker has participated in a wide variety of projects associated with enclosures, including containment systems for commercial nuclear power plants, noise control systems for commercial and institutional projects, and waterproofing systems for a wide variety of commercial high-rise and low-rise buildings. Nonpresenting Trevor Brown coauthors: Trevor Brown is a quality manager at JE Dunn Construction in Austin, Texas. Dante Marimpietri Dante Marimpietri is a test facility manager at Tremco in Ohio. Keith Simon Keith Simon serves as Terracon’s subject matter expert for hygrothermal modeling and building enclosure commissioning in Austin, Texas. Marcy Tyler Marcy Tyler is building science director at Tremco in Cleveland, Ohio SPEAKERS Portions of the building enclosure’s water barrier that may be subjected to hydrostatic water pressure need to be waterproofed in order to prevent water infiltration. This paper focuses on both horizontal waterproofing membranes and low-slope roofing membranes. Because these are often covered with some type of overburden, the remediation of water leaks can be very expensive and disruptive. Roofing and waterproofing membranes need to be evaluated for continuity immediately following their installation and prior to the completion of the original construction project. This is especially important if the membrane will be protecting occupied spaces or difficult to access during the remainder of the building’s life. Historically, testing of horizontal waterproofing and low-slope roofing membranes has been attempted with flood testing. There are many limitations and difficulties with water testing. If leaks are observed during water testing, it is very challenging to find the actual breach in the membrane that is the source of the water. Also, small leaks may not release enough water during the relatively short duration of water tests to result in the observation of water beneath the supporting structure. This paper will take a deeper dive into flood testing and other available test methods, such as high-voltage and low-voltage electronic leak detection (ELD), infrared testing, and electrical impedance testing. Testing and building enclosure consulting services should be contracted by the owner/ developer directly to help ensure their services are performed in the best interest of the owner/developer and are independent of any contractual or employment obligation to the contractor(s), design team, or manufacturers associated with a project. While test results may validate the performance of waterproofing or roofing systems, testing alone should not be used to replace tough scrutiny of the design or quality assurance measures such as mock-ups, preconstruction and coordination meetings, and confirmatory field observations during construction. Some manufacturers may require testing for certain warranties and require that the testing be coordinated through the manufacturer. In this case, the testing should still be performed by a qualified third-party testing agency and specified as such in the contract documents. There are several ASTM standard guides and practices for evaluating and locating leaks in waterproofing and roofing systems. There is no one method that will provide all the results needed. A strategic approach utilizing several testing methods in combination is typically required. The following provides some explanation of the most widely used tests and how they may be incorporated into a successful strategy for locating breaches in low-slope waterproofing and roofing membranes. TESTING STANDARDS Water Testing: ASTM D5957, Standard Guide for Flood Testing Horizontal Waterproofing Installations1 This guide addresses flood testing of waterproofing membranes installed over habitable spaces on elevated horizontal surfaces having a slope no greater than 2% (¼ in. per foot). It is not intended to be used for testing of building roofing systems. This guide is intended to be used for testing of fully adhered sheet membranes, fluid-applied membranes, or loose-laid sheet membranes. During flood tests, areas may be temporarily subdivided for convenience and drains within the test area may be temporarily blocked. Typically, water (1 in. minimum to 4 in. maximum) is held in the test area for 24 to 72 hours. The test should be constantly monitored so that no unintended changes to the water level are made and to identify any leakage. If leakage is identified before the test period has been completed, the observers should immediately suspend the test and drain the water so that any damage is minimized. A II BEC International Convention & Trade Show | September 15-20, 2021 P oseneck er et al | 91 The Leak Stops Here: Understanding the Methodology of Leak Detection for Roofing and Waterproofing Systems Roofing and waterproofing membranes need to be evaluated for continuity immediately following their installation and prior to the completion of the original construction project. Figure 1. Flood testing. separate, adjacent, small test specimen should be used to compare water-level changes that may result from evaporation. ELD Testing: ASTM D7877, Standard Guide for Electronic Methods for Detecting and Locating Leaks in Waterproof Membranes2 This guide addresses electrical conductance measurement methods that can be used to locate breaches in waterproofing and roofing membranes. It is limited to use on membranes that are considered to be electrical insulators and that are directly over substrates considered to be electrically conductive. Low voltage and high voltage are the two basic types of ELD testing. For this paper, consider low voltage as less than 50 volts and high voltage as greater than 10,000 volts. Several variations of low-voltage ELD testing are covered in this guide. Electric field vector mapping is the most common low-voltage testing technique used and will be the focus of this paper along with high-voltage testing. Low-voltage methods require a path of water across the membrane and through any overburden to any breach in the membrane. Infrared Testing: ASTM C1153. Standard Practice for Location of Wet Insulation in Roofing Systems Using Infrared Imaging3 This practice applies to infrared imaging techniques used at night for the purpose of locating wet insulation beneath a roofing membrane and above a waterproofing membrane. Several weather-related parameters affect the ability of infrared imaging to locate thermal anomalies: 1. Inside to outside temperature difference. The larger the better. 2. The rate of change of temperature in the hours prior to viewing. The larger the better. 3. The amount of sunlight prior to viewing. The more the better. 4. The wind speeds. The lower the better. Many times, these are not present and greatly reduce the effectiveness of infrared imaging. Materials covering the roof membrane also reduce the effectiveness of infrared imaging. The more heat-holding capacity and higher thermal insulating properties of these materials, the less effective the infrared imaging will be. Electrical Impedance Testing: ASTM D7954, Standard Practice for Moisture Surveying of Roofing and Waterproofing Systems Using Nondestructive Electrical Impedance Scanners4 This practice applies to electrical impedance scanning techniques used for the purpose of locating moisture and evaluating the comparative moisture content beneath low-slope waterproofing and roofing membranes. The membranes to be surveyed must be electrically nonconductive and installed over electrically nonconductive thermal insulation. Membranes that include conductive materials such as EPDM or other conductive additives cannot be accurately scanned. Metal and other electrically conductive materials at or near the surface of the membrane may also skew the results of the impedance scanning. ACCEPTANCE TESTING OF NEW MEMBRANES Testing That Relies on Water Many of the methods available for testing newly installed horizontal waterproofing membranes and low-slope roofing membranes rely on water. In the case of flood testing, water is introduced on top of the membrane with the intent of creating water infiltration past the membrane to expose leakage paths. In the case of infrared testing, evidence of water infiltration will only be detected if the substrate near the water leak is relatively wet and there is an adequate temperature differential for the moisture to be detected. In the case of electrical impedance testing, the same conditions must exist as for infrared testing, but the necessity to sense temperature differentials is not required. Flood, infrared, and impedance tests rely on a saturated substrate beneath the waterproofing or roofing membranes to identify water leakage, indicating there is a breach in the membrane. If there is a breach in the membrane but there is not adequate water in the substrate, the test may not identify any problems. In the case of flood testing, the size and location of breaches in the membrane may not pass enough water into the substrate for visual identification. The substrate’s capacity to hold water may also prevent visual identification of leakage if the duration of the test is too short. In the case of infrared and electrical impedance testing, there may be a breach in the waterproofing or roofing membrane, but either the membrane has not experienced a water event 92 | PoseneckCKer et al IIiiBEC International Convention & Trade Show | September 15-20, 2021 Figure 2. Electronic leak detection—high voltage. Figure 4. Electrical impedance testing. Figure 3. Infrared image. resulting in water infiltration or the water from previous infiltration has dried. The result may be that the test provides results indicating there is no presence of water/moisture beneath the membrane and giving the false impression that there are no breaches in the membrane. This is the reason that infrared and electrical impedance testing are not the best choices for performance/acceptance testing of new waterproofing and roofing membranes. These tests are good diagnostic tests if there are known active leaks in the membrane. They may help focus other testing methods more suited to locating breaches in the membrane to areas that have water/moisture beneath the membrane. Most low-voltage ELD testing requires the entire top of the membrane being tested to be kept wet for the duration of the test and requires a conductive substrate in direct contact with the membrane being tested. A low voltage potential is created across the membrane being tested by connecting one side of a direct-current voltage source to the structure/substrate beneath the membrane being tested. The other side of the voltage source is connected to two testing probes. Electrical current induced by the voltage potential will flow from the test probes through the water on top of the membrane and down to the structure below through the completed electrical circuit at breaches in the membrane. This type of testing can very accurately locate very small pinholes or thin spots in the membrane. There are, however, several other considerations before selecting this method of testing: 1. The area to be tested by low-voltage ELD requires that it be electrically isolated from the surrounding areas and the structure below so that other sources of low voltage do not interfere with the test. The result is that many times, items penetrating the membrane that are electrically conductive are isolated from the test. These items typically are rebar, sleeves, piping/conduit, and drain bowls. Unfortunately, penetrations in a membrane are the source of a large percentage of water leaks. 2. Because water is required on top of the membrane, it is difficult to maintain wetness on vertical surfaces. This results in vertical turn-ups, which are another source of a large percentage of water leaks, being isolated from the test. 3. Because water is required on top of the membrane, if there are breaches in the membrane, water infiltration may occur, resulting in additional damage to the substrates. 4. Because water is required on top of the membrane and many membrane repair methods require the surfaces to be dry, repairs to identified breaches in the membrane must be conducted at a different time. This may result in additional unplanned mobilizations for testing. While ELD is a very accurate means of finding breaches in waterproofing and roofing membranes, for the reasons discussed previously it is not viewed as the best option available for performance/acceptance testing when compared with high-voltage ELD testing. Testing That Does Not Rely on Water High-voltage ELD testing is very similar to low-voltage ELD except that water on the surface of the membrane is not required and there is no need to electrically isolate the area of membrane being tested. This eliminates the difficulties caused by the introduction of water and allows testing of 100% of the membrane, including portions around penetrations and vertical transitions, which are the source of a large majority of leaks. Our testing crews experienced in both high-voltage and low-voltage ELD testing prefer the high-voltage ELD. The benefits they cite for high-voltage testing as compared with low-voltage testing are as follows: 1. The setup and cleanup times are much less because there is no need for a continuous application of water and there is no need to install perimeter isolation wires. 2. One person can easily test alone, therefore increasing productivity. 3. Breaches in the membrane can be identified, repaired, and retested the same day. There are two limitations to both types of ELD testing that must be considered. The substrate beneath the waterproofing or roofing membrane must be conductive so that the only resistance preventing a flow of electrical current is the membrane being tested. For instance, if there are layers of material (insulation or cover board) beneath the membrane that block the flow of electrical current, then the flow of electrical current will be prevented by the insulating materials. This will prevent the identification of breaches in the membrane. II ii B E C International Convention & Trade Show | September 15-20, 2021 P PoseneckCKer et al | 93 Figure 7. Typical low-slope roof section. Figure 5. High-voltage electronic leak detection. Figure 6. Low-voltage electronic leak detection. The second limitation is that the membrane being tested must be nonconductive or, in other words, have a high resistance to the flow of electrical current. For example, membranes that include conductive materials such as EPDM or other conductive additives cannot be accurately tested. TESTING OF IN- SERVICE MEMBRANES ASTM D7053, Standard Guide for Determining and Evaluating Causes of Water Leakage of Low-Sloped Roofs,5 addresses methods for evaluating and identifying sources of water leakage in low-slope roofing systems that have active water leaks. Infrared and electrical impedance testing are both methods recognized by this guide that may be considered for use during the inspection phase to identify the suspect portions of the roofing system. Once the suspect portions of the roof system have been identified, diagnostic water testing to reproduce water leaks may be employed. ELD testing may now be useful if previously nonconductive substrates become conductive in the presence of water. It should be noted that this guide is not intended for construction quality control performance/acceptance testing. Because most waterproofing membranes do not tolerate exposure to ultraviolet light, they are covered with a variety of different materials. These materials, which we call overburden, are costly to remove when the membrane must be exposed in order to locate the source of leakage or repair the membrane. Without special provisions for monitoring water/moisture beneath the waterproofing or roofing system, low-voltage ELD is the only testing method available that may be capable of locating breaches in the membrane. Many times, removal of overburden is determined necessary to allow inspection and testing of the membrane. CONCLUSION For new waterproofing and roofing membranes that have a conductive substrate beneath the membrane, high-voltage ELD testing is the most comprehensive, efficient, and accurate method of locating breaches in the membrane. Unfortunately, for waterproofing and roofing membranes that have a nonconductive substrate beneath the membrane, there are no testing methods to locate breaches in the membrane without recreating the leak with water. REFERENCES 1. ASTM Subcommittee D08.22, Standard Guide for Flood Testing Horizontal Waterproofing Installations, ASTM D5957. West Conshohocken, PA: ASTM International, 2013. 2. ASTM Subcommittee D08.22, Standard Guide for Electronic Methods for Detecting and Locating Leaks in Waterproof Membranes, ASTM D7877. West Conshohocken, PA: ASTM International, 2014. 3. ASTM Subcommittee C16.30, Standard Practice for Location of Wet Insulation in Roofing Systems Using Infrared Imaging, ASTM C1153. West Conshohocken, PA: ASTM International, 2015. 4. ASTM Subcommittee D08.20, Standard Practice for Moisture Surveying of Roofing and Waterproofing Systems Using Non-Destructive Electrical Impedance Scanners, ASTM D7954. West Conshohocken, PA: ASTM International, 2021. 5. ASTM Subcommittee D08.20, Standard Guide for Determining and Evaluating Causes of Water Leakage of Low-Sloped Roofs, ASTM D7053. West Conshohocken, PA: ASTM International, 2017. 94 | PoseneckCKer et al IIiiBEC International Convention & Trade Show | September 15-20, 2021 Figure 8. Low-slope roof with vegetative overburden.
