Caecilius wrote:
On Sun, 22 Dec 2019 17:28:28 -0000, "Mr Pounder Esquire"
wrote:

Bungalow, back end south facing. I was unhappily on the roof about 5
years ago scrapping and brushing the moss off. The tiles are very
rough and are like steel.
I'd read that stringing a length of copper wire over the ridge kills
moss, so I did it. The moss returned on the back end of the roof,
never mind and ******** to it, I'm not going up there again. Since
Autumn chunks of moss have been falling down almost every day. Maybe
the copper wire takes time to work?

The best thing I've found for killing moss is benzalkonium chloride.
It's the active ingrident in most patio and decking treatments, but is
available much more cheaply as "BAC 50".

I buy 5 litres each year, which is enough to treat my drive at patio.
I've not tried it on my roof yet though.

No moss on the drive. I'm too bloody old to climb back on that roof again.