EFVM

Electric Field Vector Mapping

Jersey Infrared Consultants, pioneers in the infrared inspection industry since 1984, are pleased to offer another form of non-destructive testing – Electric Field Vector Mapping, or EFVM.

EFVM is a type of nondestructive testing used to locate a breach or void in a waterproofing membrane. During testing, a low-voltage electrical current is used to create an electrical potential between a non-conductive membrane and a grounded conductive or conductive substrate.

The most common of the applications for EFVM include:

Q/A inspections of waterproofing membranes prior to installation of pavers or overburden
Locate sources of leaks in IRMA or uninsulated roof systems
Identify breaches or holes in parking deck or patio membranes

Jersey Infrared Consultants’ safety compliance, background checks, and drug screening programs are a part of our commitment to providing an unequaled level of client care and quality service. Although thermography is our core business, we are always on the lookout for complimentary test technologies that help to address our clients’ needs.

Contact us to schedule your EFVM testing.

EFVM Sample Report

EFVM Project Worksheet

FAQs

What Is EFVM?

Electric Field Vector Mapping, or EFVM, is a type of non-destructive testing used to locate a breach or void in a waterproofing membrane. A low-voltage electrical current is used to create an electrical potential between a non-conductive membrane and a grounded conductive deck or substrate.

Used in Europe since the 1980s, EFVM was introduced to the United States in the early 2000s. Since that time, it has gained recognition from waterproofing manufacturers, building owners, and property managers, and roofing professionals.

What are the advantages of EFVM?

There are many advantages to using EFVM. Testing can be performed on sloped roofs and vertical walls.

Some of the advantages include the following:

Able to locate the exact location of the breaches or holes
Testing can be performed as immediately following membrane installation
Defects can be repaired and retested during the same site visit
May be used on IRMA, ballasted, uninsulated roofs, or those covered with overburden
Locate and repair breaches/holes before water has a chance to enter the roofing system

How does EFVM work?

A grid field is established on the area to be tested by laying a low voltage wire directly on the roof surface. Penetrations, such as drains or projections, will be isolated from the grid. An electrical charge is attached to the grid wire and the membrane is sprayed with water. This completes a temporary electrical circuit between the non-conductive waterproofing membrane and the conductive structural deck.

A watertight membrane will isolate the potential difference. Breaches or holes in the membrane will cause an electrical connection to occur. Using test probes, our certified inspectors read the directional flow of the current with a potentiometer to locate the point of entry with pinpoint accuracy.

All breaches are numbered and documented. If qualified personnel are on site at the time of the test, repairs can be carried out and the area retested immediately.

HOW DOES EFVM DIFFER FROM ELD?

Electronic Leak Detection (ELD), referred to as “high voltage” leak detection, relies on a conductive deck as the ground source and the membrane as the insulator. A broom like device consisting of numerous small conductive bristles is used to “sweep” the roof during testing.

ELD requires that the test area be completely dry and be exposed. A good grounding component, such as a metal drain, flashing or rebar, must be exposed and able to provide a solid connection to the deck material.

Advantages of the EFVM method include the ability to test under different weather conditions and with certain types of ballast or overburden in place. Current industry practice prefers EFVM over ELD for investigation of possible seam defects.

Are there any limitations of EFVM?

Candidate roofing systems for EFVM testing include those constructed with metal or concrete decks. If the subject roof has a wood deck or insulation between the deck and the membrane, it must have a mesh of grounding material that was installed at the time of roof construction.

Safe access to all areas to be tested must be provided. Work cannot be conducted if the roof is covered in ice or snow; winds exceed 15 mph; or when daytime temperatures are below freezing.

What must be provided on site at the time of the test?

Upon scheduling your project, we will provide you with a detailed checklist to guide you in preparing for the test and items we require at the time of testing. Typical items include: completion of all membrane installation/repairs, site-specific safety requirements, and scaled drawings of the area(s) to be tested.

At the time of testing, the following are required:

Hose and water available for all areas to be tested
Physical access to all subject roof areas
120v electrical receptacle with ground

How are results provided to you?

EFVM testing provides real-time results. This allows for immediate repairs of any located breaches or holes. In such cases, repaired areas may be retested during the same site visit.

A written report detailing any problems located and results for any retested areas will be provided. This report will also include a drawing of the roof indicating the location of all findings as well as the location of any wire grid (where applicable) to allow for future testing.