So the roof is finished! Well the waterproofing layer and the installation of the rooflights that is. Before we move on to the final phase of the roof (creating the garden), we have decided to have our roof leak tested as once the soil, gravel and plants are in place, it would be very difficult to find and then rectify any leaks.
We’ve had Thornton Consultants on site to run a series of tests to check all the joints and laps on the roof system for any signs of leakage.
We’re doing three kinds of test:
- Visual inspection: this involves looking at all the joints and highlighting any areas that could be susceptible to leaks
- Wet test (also known as earth leak detection): This method of testing is more environmentally-friendly than a flood test method as it uses much less water (using tens of gallons of water rather than the hundreds used for a flood test). It’s based on the electrically conductive properties of water. Most membranes are insulators and do not conduct electricity, but if there is a leak and water is seeping through the membranes, the electrical current running through the water can be measured as it earths to the concrete layer below the membranes, pinpointing the exact location of the leak.
- Differential pressure test: This test involves air being drawn through a surfactant (a substance, such as a detergent, which can reduce the surface tension of a liquid and allow it to foam) which is applied over the laps of the bitumen. If bubbles form on the seams it suggests air is being drawn up through the mineral layer and that the lap’s integrity needs to be improved.
Next, we’ll add protective drainage layers then it’s time to get started on the final layers of the green roof, including gravel, soil and plants.