Flood Test
A simple but effective way to check if the membrane is intact and has any defects . Once the outlets have been blocked and the roof filled with a limited amount of water it is simply a case of waiting to see if a leak occurs below .
There are many limitations and pitfalls in flood testing and it should always be carefully carried out . Due consideration has to be given to the weight loading that a flood test will add to a roof , and when releasing the flood will the drains and outlets be able to cope ?
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 . There should be an alternative way to get the water off the roof and help remove the water once the leak starts . The flood can also saturate large areas of insulation and the deck which could cause issues in the future if the moisture is trapped .
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 completely flat with no undulations in the surface .
.
ADVANTAGES Finishes do not have to be removed .
Summary
All a flood test will reveal is that there is a leak and the cause of the leak is very unlikely to be identified meaning the search for it the cause will still have to occur . Flood testing can be a very useful tool in a leak investigation to eliminate sections of membrane as the cause of a leak . A flood test is a very crude way of testing a roof and the potential for damage to the roof and leak site has to be considered before it should be undertaken .
DISADVANTAGES
Not an accurate test no indication of the leak pathway .
Not weather dependent . Potential damage from flood / leak .
Potential damage / failure of roof from flood test .
Will not work on pitch roofs .
Areas potentially left untested .