Thread: Chemicals to clean moss off hut roof

I'm after the most aggressive moss killer known to man !

West Coast cabin with moss like shag pile carpet on the shady side
I did the front/ sunny side with the water blaster this week and for most off. But some still stuck on the colour steel.

The back / shady side is epically thick and hard to blast off
This is not a 30 seconds and it dissolves

Who among you actually knows what will kill this stuff ?
Maybe a pre treatment or two.
Treat and blast and the treat again to get at the roots as well

Going back hunting, fishing and golding in January and want to take something that will do everything except melt the roof !

Bleach is the answer.

The primary active ingredient in the moss and mould killers is Benzalkonium Chloride. 30 Seconds concentrate is <10% of this active ingredient.
I'd say just buy a 50% solution here : https://thesourcery.co.nz/products/b...onium-chloride
It'll kill any moss or mould it contacts so if it is thick it may take a few applications simply by the fact of you can't get the solution through it all in one go.

That'll sort it. Don't breath it in or get too much on your skin it's pretty unpleasant stuff.

Originally Posted by Makros

The primary active ingredient in the moss and mould killers is Benzalkonium Chloride. 30 Seconds concentrate is <10% of this active ingredient.
I'd say just buy a 50% solution here : https://thesourcery.co.nz/products/b...onium-chloride
It'll kill any moss or mould it contacts so if it is thick it may take a few applications simply by the fact of you can't get the solution through it all in one go.

That'll sort it. Don't breath it in or get too much on your skin it's pretty unpleasant stuff.

interesting... will give it a try, hopefully it won't peel off my roof paint. thanks for the info.

wet n forget rapid. pink bottle that connects to garden hose. pulled moss/mold/lichen off caravans like crazy
wait for a day when no rain is expected for 3-4 days
spray and thats it. you can hose it off after a while but no high pressure wash

Bleach is pretty much instant, it's alkalinity and the chlorine destroy moss on contact. "quats" (like benzyl alkonium chloride) takes several months to work but does have some residual activity. Break down product of bleach is salt, benzyl ac will make the water foam like beer. That's only important if you collect drinking water mind you.
In a perfect situation bleach water blast then benzyl ac to get some long term activity.

Buy Surrender from Bunnings/Mitre10 and use it at the rate of 15ml to the litre , but make sure the moss is wet beforehand so that the moss will fully absorb the spray .
Or if you already have 30 Seconds use it at the rate of 75 ml to the litre and add a squirt of dish washing liquid as well ( for both).

Copper spray is what I used to use. I forget what it was actually used for maybe orchids? It was a blue powder that you mixed with water.

Washing powder

Thats what people use here,even at the museum on 500 year old ceramic tiles.

A Copper wire along the ridge line will keep it at bay. For moss on your lawn use Iron Sulphate when its raining

Originally Posted by norsk

Washing powder

Thats what people use here,even at the museum on 500 year old ceramic tiles.

That will work in the long term , but will need a regular application . The use of Surrender will give a hard hit and with the washing powder used regularly as a maintenance program it will work as a preventative.

All the above suggestions will work but the 'carpet' will remain until the active ingredient has broken down or washed away. Once the moss is dead, you will need to remove the carpet or it will act like a germinating medium for new moss.

Regular treatments and maintenance is the key for future south aspect roof happiness.

Thanks to all who have given input on this problem.

There are plenty of products and techniques there for me to try in January when I am back over there

Actually it was pretty ok up until 2020 and then the last 3 years I didn't visit often and then when I did I camped elsewhere on the property
Now I'm using the cottage again as a hunting and fishing base
Three years of exponential moss growth and it looks like a corral reef up there

Ideally you might want to treat it now (chlorine, 30 seconds, dairy sanitizer etc) then water blast it when you go back in a months time. Give the moss and lichen some time to break down and release.


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Originally Posted by Harryg

A Copper wire along the ridge line will keep it at bay. For moss on your lawn use Iron Sulphate when its raining

Excellent on timber shingles and tiles but not on a iron roof though, it creates a battery and the iron rusts. Funnily enough an unpainted galvanized iron roof resists moss pretty well as zinc is toxic to it