Low voltage leak detection
Low voltage leak detection finds a breach through a wetted membrane. A thin film of water carries a small signal across the roof; wherever water can get through, so can the current, and a probe pair traces the field straight to that point. It tests finished roofs in service, including many membranes under pavers or vegetation, without lifting the overburden.
When this is the right test
The roof that already leaks
Water is getting in somewhere, and the method that traces current the way water travels finds the same path water uses. The breach is marked where it is, not where the stain shows up two bays away.
Under the overburden
Pavers, ballast, vegetation. Lifting them to inspect is its own project with its own cost. Where the assembly allows, we test with pole electrodes worked across the finished surface, so the overburden stays where it is. Scanning-platform testing needs direct contact with the membrane, so on those roofs it happens before the overburden goes down.
Close-out on a wetted field
New membranes certified before sign-off, mapped to the square inch, without a flood test: no standing water, no loading the structure, no waiting a day to drain it.
How the test works, in plain terms
A boundary cable is laid around the perimeter of the test field, with drains and penetrations isolated. A thin film of water goes down on the membrane, and a small signal is applied across the assembly. An intact membrane keeps the circuit open. A breach closes it, because water in the breach conducts, and the current creates a readable field on the surface.
Two hand-held probes read the voltage differential, which points along the direction of the current like a compass needle. The technician follows it to the point where the readings converge: the breach. Each one is marked, photographed and mapped in the report, then re-tested after the repair.
A dry membrane, vertical surfaces, or pinhole hunting on a new install calls for high voltage leak detection instead. If you are not sure which the roof needs, start at electronic leak detection; the roof decides.
Low voltage questions
What is low voltage leak detection?
A water-assisted electronic test, sold under several names: EFVM (Electric Field Vector Mapping), LVIT (Low Voltage Integrity Testing), LV testing. All are the same idea: a thin film of water on the membrane carries a small test signal, and wherever the membrane is breached, current flows through. Technicians read the voltage field with a pair of probes and follow it, vector by vector, straight to the breach.
Does it work on a roof with pavers or a green roof?
In many cases, yes. This is the method for it. Because the signal travels through moisture rather than needing brush contact with the bare membrane, low voltage can test through overburden that would otherwise have to come up. Whether it works on a specific roof depends on the assembly; tell us what is on the roof and we will give you a straight answer.
What does the roof need for the test to run?
A conductive path under the membrane (most roof decks provide one) and a test field isolated by a boundary cable around the perimeter, with drains and penetrations accounted for. Setup is most of the craft: the method is only as accurate as the field, which is why specifications require an experienced agency.
Which membranes can be tested?
Single-ply membranes, hot melt, liquid-applied systems, built-up felt, asphalt, torch down, silicone, and white EPDM, the same range as the dry method. If the membrane is exposed and dry, high voltage may be the better tool; the roof decides.
Tell us about the roof
Membrane, deck, what sits on top of it, and what you are seeing inside. If the dry method fits better, that is the answer you will get.