Sadly, it is all to often that we get a job requiring us to either re-waterproof a roof, or roof terrace, or even an entire building itself!
There does not seem to be enough focus on ensuring that waterproof membranes are installed to last, and that drainage systems are built big enough to handle the amount of water run off required to stop the water backing up against the property.
What we can assure you of, is that when we fix a waterproofing issue, it is fixed to last.