Cleaning roofs can be a dangerous and difficult task!

especially if you have a high pitch roof and are afraid of heights. However, it is a task that must be completed to avoid damage which can lead to leaks and expensive repairs. Algae, moss, and lichen can grow on almost any surface and once these nasty organic growths have developed they can be tough to remove.

To treat these organic growths and stop them from damaging the paint and functionality of your roof it is important to use proper methods in order to ensure longevity.

Not every roof is the same so make sure you are using correct methods for your particular type of roof.

Heres a quick guide on how you can clean your roof. Note, that there is a separate method for Asphalt Shingle Roofs. These methods below are only soft wash methods and do not include any pressure washing. 




Acquire a concentrated Benzalkonium Chloride based product and mix with water according to the product's instructions.

Benzalkonium Chloride is great for treating algae, moss, and lichen. Even though it can take a few months to achieve results, it will act to stop regrowths.

Protective equipment should be used when handling Benzalkonium Chloride products. This includes: gloves, goggles, a respirator, and protective clothing.


Cover all Plants that are at risk of over-spray.

Even though Benzalkonium Chloride is not as harsh as Sodium Hypochlorite, it is better to be safe rather sorry


If on tank water, down pipes or the tank should be disconnected. You should allow at least 3 weeks and a few good rain showers before reconnecting.


When dealing with heights, make sure you use appropriate safety equipment to minimise the chance of injury.

This means that the ladder you are climbing up should be secured properly with multiple anchor points to stop the ladder from falling over or slipping out from underneath you. Even if you are using rope to tie your ladder in, it is still better than nothing.

If you are climbing onto your roof to spray or spraying from the edge of the roof from a ladder, it is wise you use a safety harness.


Spray the target area thoroughly.


Once you have finished, wash down the surrounding areas/ plants and equipment with water.

You are not required to wash your roof with water after spraying.


In 2 months time; inspect your roof to see if the algae, moss and lichen has started to die.

If you think that the volume or concentration was not enough, you may need to reapply at a slightly higher volume or concentration.

A treatment every 1-2 years will ensure you keep those organic growths away.