How To Kill Moss On Roofs

Moss loves to grow on roof tiles. The surface of roof tiles are generally rough and this is a perfect place for moss spores to hide and grow. Moss loves a cold, damp and inhospitable environment so north facing roofs are usually the worst affected. There are many types of roof moss killer on the market however, not all are easy to apply and can be expensive.

Will moss damage my roof?

Moss soaks up water like a sponge. Now this is not a problem in the summer however in the winter, when the temperature drops, the moss can freeze and when things freeze they generally expand. The expanding and contracting of the moss covered saturated area can eventually lead to the damage of your roof tiles.

Don’t worry! You don’t need to rush up a ladder armed with a sprayer filled with roof moss killer at the first sign of frost. The damage can take years to occur. Killing moss on roofs is more of a “damage limitation exercise”.

How much does it cost to kill or treat moss on roofs?

The simple answer is, it should not cost a lot of money. Professional roof moss killers can be expensive as can the professional roofers needed to apply the chemical. The use of professional roofers should not be underestimated. Clambering up ladders and on to delicate roof tiles at 25 feet up is best left to the professionals. This should be the main cost of killing moss on roofs.

One of the most effective roof moss killers is Sodium Percarbonate. It’s an easy to apply granule which, when mixed with water, produces oxygen. It’s this reaction that breaks down the small roots (rhizoids) which moss needs to survive. It also has the added benefit of killing off the spores which the moss releases in order to reproduce, therefore reducing the chances of moss multiplying and populating your roof.

As a rough guide, 5 Kg of Sodium Percarbonate will treat the roof of an average size semi-detached house. It should take half to one day to apply depending on ease of access for a professional roofer.
Scroll down for the Latest Sodium Percarbonate Prices.

There are many benefits to using Sodium Percarbonate as a Roof Moss Killer.

  • Sodium percarbonate can be used in the rain or if rain is imminent.
  • Sodium percarbonate is eco friendly.
  • There is no damage to grass or plants.
  • There is no damage to septic tanks if the there is roof run off to these systems.
  • It prevents moss regrowing on your roof.
  • Easy and quick to apply. No going up and down a ladder refilling spray tanks.
  • Direct application. No spray drift of nasty chemicals.

How to use Sodium Percarbonate as a Roof Moss Killer.

  1. Sodium Percarbonate is best applied in damp conditions. If it’s not raining use a hose pipe to damp down the tiles, this enables the granules to stick to the tiles and starts the oxygen producing process.
  2. Wearing gloves, spread the sodium percarbonate by hand over the whole roof. After about 15 minutes the roof will turn white as the water reacts with the sodium percarbonate. Sometimes there is a white residue left which is the by-product of the water and oxygen reaction. This is soda ash, an inert substance which will get washed down by the next rain shower.
  3. What happens next? Over the following days the moss will turn brown and die. Over time it will slowly disintegrate. Sodium percarbonate is a powerful cleaner so your tiles will start to look cleaner as it works it’s magic.


how to get rid of moss on roofs
Roof sprayed with Water and then sprinkled with Sodium Percarbonate
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  1. Great to read this – do you have any advice on how to spread? My roof is on a single story barn so happy to do myself using roofing ladder so should I start at the top and work down the ladder then move ladder across a few feet and repeat?

    • Hi Thank you for getting in touch, yes as you suggest, work from the top down and then move across and down the roof again. Its a great product and will kill the moss, let me know if I can help further.

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