How Does the Low Voltage ELD Method Work?

The low voltage method utilizes the conductive properties of water to create a signal when there is a voltage drop to help test and locate leaks in the roof membrane. The process starts with a conductive boundary cable being laid down on the roof membrane which goes around the perimeter of the roof or designated field you choose to test. All roof penetrations such as roof drains and any other conductive penetrations not coated in membrane or liquid applied products must be shunted off properly to keep the field clear of any potential voltage loss. Then the roof membrane is sprayed down with a thin layer of water so the entire surface in the test field is wet. After wetting the surface, the generator is connected to the positive terminal on unit. The negative terminal is connected to a suitable reference or ground on the buildings structure. There is now a low voltage field created for testing the waterproof membrane.

Low voltage testing has several different terms such as EFVM (Electric Field Vector Mapping), LVIT (Low Voltage Integrity Testing) or just LV Testing. Regardless of what term you choose it is all a form of Electronic Leak Detection and Leak Testing (ELD)

How Does the High Voltage ELD Method Work?

The High Voltage ELD method works with a High-Voltage sweep of a roof and a testing unit producing a current backed by as much as 30,000+ volts of electricity at a very low current. IT is applied using a special electrode brush made with highly conductive metal bristles. If current passes through a hole or breach of the waterproof membrane, the testing unit will then make an audible sound as well as create an electrical arc. Our technicians are trained to understand when an audible signal is created due to either a breach in the membrane and/or areas of some membranes that are installed incorrectly (too thin). This method is very safe, accurate and a very efficient, cost effective way of testing for leaks in waterproof membranes. This high voltage method is commonly and more effectively used on vertical, sloped, small and difficult to reach areas of waterproof membranes.

High Voltage Electronic Leak Testing is performed on dry horizontal, vertical and sloped waterproof membranes. The benefits of High Voltage Testing (ELD) is that it is an especially more accurate way of testing vertical and sloped membranes over the Low Voltage, Electronic Field Vector Mapping Method. Regardless of what you may read or hear, the High Voltage method should be the first choice in testing these vertical and sloped membranes. Unlike the Low Voltage, Electronic Field Vector Mapping method, the membrane being tested needs to be dry. When testing vertical or sloped test areas, it can be very difficult to keep these areas wet. IF the areas are not kept wet during the Low Voltage testing, the procedure becomes ineffective and results can be misleading, incorrect, or completely inconclusive. This is why the High Voltage method achieves more positive results time and time again when testing vertical and sloped waterproof membranes, including very small areas such as planters and difficult to reach areas.

We can locate leaks on the following flat roof surfaces:

  • Asphalt roofs
  • Silicone roofs
  • Hot melt systems
  • White EPDM roofs
  • Built-up felt systems
  • Single-ply membranes
  • Liquid-applied systems