When the extension at OCC was built nearly 20 years ago, a hidden flat roof was used, with limited visibility / access… Whilst checking known issues shortly after heavy rain we noticed a problem (tip toes looking out of a Velux window!) – several centimetres of standing water on the flat roof, a patch of grass around a drain and a very tired tennis ball:

e.g. standing water, a bunch of debris & several years worth of moss. There’s a blocked roof drain to the right of the plank…

The drain was cleared (which was really, really satisfying!)

We cleared up the moss & removed the unused tiles:

The flat roof drain was left clean:

We’ve added a check to our regular maintenance checks to ensure that we don’t get a blockage again, and so that our successors know to check this area. There’s been next to no moss or debris build up in nearly 12 months now, leaves don’t seem to collect in this area (unlike most of the other drains around OCC!).

Thankfully there was no harm done – if the roof had overflowed or started to leak whilst flooded, we likely would have seen significant damage.