Rainwater problem with roof

Benzalkonium chloride sprayed on from the ground. It will kill the moss and keep it clear for a few years, so spray every 2/3 years.

The moss will be killed almost immediately and turned to a dust over three months or so - the rain will wash it off. You may/will need clear gutters before treating.

Reputable companies don't pressure was roofs by walking over them. They will set up scaffold towers and use long poles

Thanks for the info. I liked the idea of the chemical solution, but my wife has put me in the dog house for even considering it.

I hope Mrs Halmarack doesn’t use a deodoriser/sanitiser in the washing machine…they can contain circa 2% BAC…

That may eventually swing it.

Unfortunately, since moss was reclassified as a plant it is illegal to use BAC to kill it. However, as far as I'm aware there is nothing to stop you using the detergent properties of BAC to clean the roof tiles (other than The Management, of course...).

Or indeed many kinds of domestic antibacterial cleaning sprays or wipes, eg:

Or eye drops

about 1/10th the level

Isn't there a trick with a length of copper wire along the apex ?

Possibly, but if the intention is to use "leached" copper from the wire to kill the moss, that would come under the COPR.

There's always that powerful chemical H20.

I think dettol was full of it. Or jeyes fluid.

I have found it the only thing that clears black patio pox

Put it up there for its decorative effect?

Which will work. Do this only if the gutters etc. are copper (or plastic, I guess) as well: otherwise the copper runoff "eats" the zinc, steel, or galvanized steel guttering...

Thomas Prufer

I've always resisted this idea because all our down pipes have diverters to water butts attached. Excess rainwater then goes to soakaways so it probably won't do them any good either & I don't really want to experiment to find out.

Doesn't seem to mention lichen which often lives along side moss.

Until you become sensitised to the awful stuff and wake up in the night looking like one of those chinese dogs with lots of flappy skin in their face.

Then you need the NHS to provide the preservative-free versions, but the label on Cosopt or its generic versions says 'Do not refridgerate or freeze, or store above 25C'.

Tricky this summer.

Spraying BAC onto the roof of a 3 story building from the ground sounds like a really daft idea, unless you are wearing a full Nuke/Biological protection suit.

The professionals use long hollow poles to deliver the diluted chemical to the roof and a brush type head to spread it on the tiles. It's a similar method that window cleaners use these days use to deliver de-ionised water to the brush to clean to upper storey windows.

BAC is even found in many mouthwashes. Fairly safe stuff.