The nitty gritty on how electronic leak detection works.

At ILD, we use a leak detection method called EFVM.  It's a low voltage test method, which is more accurate than flood testing.


What's EFVM?

EFVM is a state of the art testing method that enables us to locate defects in roofing membranes. 

Sometimes these defects happen during or after installation – perhaps due to mechanical damage caused by others, or workmanship defects, material defects, design faults, weather related defects or membrane deterioration.

By using EFVM, you’ll be able to pinpoint your leak and repair it more effectively.

How does EFVM work?

EFVM creates an electrical potential difference between a non-conductive membrane surface and a conductive substrate, which is earthed or grounded.

By applying water on the membrane surface and using the water as a conductive medium, an electric field is created and a breach in the membrane creates a vector (ground fault connection).

Your EFVM technician then reads the electric flow travelling across the membrane, enabling breaches to be mapped with pinpoint accuracy.


Some nifty diagrams to explain this further.


This membrane is watertight ...

If the membrane is watertight, the electricity can't find a ground earth connection. In other words, there's no leak.


... this one is not.

If the membrane isn't watertight, the electricity makes a ground connection and is pulled towards the positive pole, effectively locating the leak.

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The substrate of your building will determine how we go about testing for leaks.


Membrane on plywood (non‐conductive substrate)

EFVM® requires (VMG™) Vector Mesh Grid between the plywood substrate and the membrane. If there is a breach in the membrane this will create a connection to the VMG™ beneath.  
The VMG™ is a stainless steel grid that is a patented conductive medium when used with roofing/waterproofing systems that incorporate Electric Field Vector Mapping (EFVM®) leak detection systems. 

Membrane on insulation (non‐conductive substrate)  

EFVM® requires (VMG™) Vector Mesh Grid between the insulation and the membrane. If there is breach in the membrane this will create a connection to the VMG™ laid on top of the non‐conductive insulation.



Membrane on concrete (conductive substrate) - no mesh required

EFVM® electronic leak detection can be performed on the membrane  application after the installation of the membrane. The concrete and reinforcing steel will create an electrical potential difference if there is a breach in the membrane.