Flood Test
The outlets are blocked with a suitable bung and the roof filled with a limited amount of water to cover the membrane . Dye can be added to differentiate the water from other areas .
When carrying out a flood test the depth should be limited to 25mm to prevent any low upstands being overwhelmed and precautions taken below to make sure the damage is limited .
The leak needs to be monitored from below to prevent extensive damage and the water will need a minimum of 4 hours on the roof to ensure the membrane is intact . A flood test will not pick up potential pathways such as partial laps and a visual inspection should be carried out .
A flood test can be carried out with existing finishes in place but on inverted roofs it should be considered that the flood may not reach all the roof area . Water depth can vary across the surface and some areas will naturally be much deeper than others unless the roof is zero falls and has no sumps , outlets or gutters .
Rainwater Outlet Testing
Rainwater outlets are one of the most vital parts of the roof envelope and their performance and integrity should be checked as part of preplanned maintenance or leak investigations .
The testing should be able to check as many individual components of the outlet separately to isolate any defect and allow an effective repair . This is also important to carry out before a flood test to ensure that the outlets function properly and will allow the water to drain away .
An outlet can be made of up to three parts and the pipework should be tested first , then the spigot ( joints between pipework and interface ) and finally the interface , this should ensure the roof is not leaking because the water backs up or enters the roof due to a perished seal or the interface has failed .
Simulated Rainfall Test
Water is sprayed from a suitable water source such as a hose in a controlled manner to recreate a controlled rainfall . This can be used to test the integrity of roof details and penetrations to the fabric of the building and identify any failures in the waterproofing .
20 Minutes of testing with a hose at standard water mains pressure is an approximate simulation of 7-8 hours heavy rainfall . Care is taken to avoid using unrealistic testing and overwhelming a system .
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