EFVM testing requires that the substrate in which the membrane being tested is placed over is conductive and earthed. Reinforced concrete buildings with concrete decks roofs are earthed through the reinforcing steel and are easily tested.
Modern lightweight construction materials which are non-conductive, like plywood and fire cement sheets, require ILD Vector Grid installed beneath the membrane prior to the membrane being placed. Should the roof system include insulation (Thermal or Acoustic) the Vector Grid ise directly beneath the membrane to provide ILD to conduct an EFVM test.
- Geotextile layer
- ILD Vector 9 cable
- Waterproofing layer
- ILD Vector Grid
- ILD connection box
- Insulation buildup
- Damp proofing
- Primer or separation layer
- Concrete Roof/Deck
When the roof is of lightweight design with no overburden the buildup would read:
3. ILD Vector 9 cable on surface
4. Waterproofing layer
5. ILD Vector Grid
10. Plywood/lightweight roof deck
Many large scale greenroof developments now utilize EFVM testing prior to and after overburden placement.