- Electrical field vector mapping (EFVM®) is suitable for electrically conductive and electrically grounded roof decks such as steel and reinforced concrete roofs. EFVM® can be used on wooden roofs or precast concrete slab roofs if a conductive layer of metal foil or mesh is applied to the roof deck before the waterproofing layer is installed. The decision to use EFVM® must therefore be made at the design stage.
- Destructive testing is used for preformed waterproofing membranes. The membrane is perforated at the lowest parts of the roof deck to check for the presence of any water beneath the membrane. The penetrations made through the waterproofing must then be repaired to restore the membrane’s integrity. Destructive testing may be the only method that can be used on older existing green roofs. For new projects, EFVM® should be considered during design, as it is simpler, safer and non-destructive of the waterproofing system.
- Flood testing is suitable only for flat roofs with slopes of up to 2 per cent. Flood testing involves temporarily blocking the roof drains and flooding the roof membrane with a known depth of water for a set period of time. The weight loading of the roof must be checked against the weight of water that will sit on the roof during the test. This ensures that the structural integrity of the building is not compromised.
It is advisable to perform an additional leak test prior to installation of the growing substrate if significant time has elapsed since the waterproofing was completed, or if there has been construction activity or other traffic on the roof. The repair of leaks presents a greater challenge once the growing substrate and vegetation are installed. However, EFVM® leak detection should be performed at this time (project completion).It may also be carried out prior to the expiration of membrane warranties.