In Manchester, according to the novelist Jeanette Winterson (in “Why be Happy when you can be normal” – a joyous, sad read ) slate roofs on two up two down terraces are built at 33 degrees – to get the optimum balance for steady draining and no external or internal water damage that happens if the gradient is too great and the water cascades down the roof in a torrent too fast for the gutters to handle.

Why the attention to roofs…read on…

Tags: behaviour