Visual inspection is critical at least once every three months (or after a storm or bad weather) to look out for instances of ponding, bubbling of membranes, tears or cracks or for any area of the roof that may have been damaged. If you see any of these issues, your roofing membrane probably needs replacing. Keep an eye on the interiors of all flat roofing, whether it’s the garage, garden office or home extension. The first sign of water damage is a signal that the roof has been leaking for some time and requires immediate attention.