EFVM® is a low-voltage test method that creates an electrical potential difference between a non-conductive membrane surface and conductive structural deck or substrate, which is earthed or grounded.
Developed by ILD® Germany in the early 1990s, EFVM® quickly became a valuable tool for leak investigations on existing systems. Introduced to North America in 2001, the EFVM® testing procedure has become the standard for waterproofing verification. To date, ILD® has tested over 200 million square feet of membrane worldwide, such as hot or cold liquid applied membranes, coatings, and various sheet membranes. Only ILD® technicians are trained and certified in performing the EFVM® test, utilizing ILD®’s proprietary training manual.
An electric field is created by applying water on the surface of the membrane and using the water as a conductive medium. The EFVM® equipment delivers a low voltage pulsating electrical charge between the non-conductive waterproofing membrane and the conductive structural deck.
A watertight membrane will isolate the potential difference, while breaches in the membrane will cause an electrical connection to occur. Our certified inspectors read the directional flow of the current with a potentiometer to locate the point of entry with pinpoint accuracy.
The EFVM® technicians then complete the test by conducting a visual inspection of all wall junctions, perimeter details, and membrane penetrations. All breaches are numbered to allow for repairs by the waterproofers onsite and are retested to confirm watertightness. A report follows with picture documentation of every breach and a detailed drawing noting the wire placement and breach locations.
Small punctures, membrane splits or mechanical damage to waterproofing membrane result in wet insulation, mold, and costly interior damage. Leaks can go unnoticed and the water exit location might not correspond with the point of entry. Previously, lengthy and costly leak investigations were necessary to locate a membrane breach, especially in protected roof membrane assemblies, garden roofs, or parking and plaza decks.
EFVM® is unique in its ability to test the integrity of waterproofing membranes with overburden or ballast. This non-destructive method is important for green roofing systems because the EFVM® test can read through the overburden and ballast, while still providing perfectly accurate results.
What better way to get peace of mind when it comes to quality control testing or troubleshooting problems in waterproofing membranes?
A. Small electrical pulses are directed onto the membrane. The electricity searches for a ground connection.
B. If the membrane is watertight, the electricity is isolated and does not find a ground connection.
C. If the membrane is not watertight, the electricity makes a ground connection and is pulled toward positive poles.
© International Leak Detection 2012