You will be pleased to know that when it comes to removing roof moss, concrete tiles are by far the easiest to work with.

Moss growth is often significantly worse on the north facing side of your roof, underneath hanging tree branches or other more shaded areas of the roof.

This is a popular option with many professional roof cleaning companies when cleaning concrete roof tiles. The moss and any roof contaminants are forcibly removed with a high power water pressure washer. Often this method is the messiest as the watery mud can quickly overflow gutters and tends to splash all over walls, windows and patios - A thorough and professional clean up of the surrounding area is required after pressure washing a roof.

One of the biggest problems with pressure washing is the colour of the roof afterwards. Roofs typically have a brown/grey colour after only a few years of natural "weathering". By using a high powered washer most of this colour is removed and the roof looks "bleached" - an unappealing yellow/white colour.

Pros

• Easy for local roofer to carry out such work
• Inexpensive
• Very effective at removing all moss/mould from roof
• A good opportunity to check the roof and replace any broken concrete tiles

It is always recommended that a fungicide is applied to the concrete tiles afterwards as this will inhibit any moss growth for several years. Check out our moss killer chemicals page for more information.

Cons

• A high powered pressure wash can ruin the weathered look of the roof
• Incorrect use of washer can lead to flooding of the house
• Extremely messy
• Expensive roof coatings are often sold as a package with a pressure clean

Here you will find lots more information specific to roof coatings.

Many roofing contractors prefer to remove the roof moss by hand without the use of specialist pressure washing equipment. Typcially a trowel or even a wire brush is used. A moss killer chemical or other preventitive should be used afterwards to inhibit re growth.

Pros

• Inexpensive
• Can be done by any roofing contractor
• Minimal mess
• Minimal change in roof colour

There are however a few important things to consider:

Cons

• You can only apply roof coatings after a roof has been thoroughly cleaned - ie with pressure washer
• Manual moss removal will not dramatically improve the appearance of the roof

Further Reading:

Copper - A Natural and Organic Moss Killer
Moss Killer Chemicals
Do Roof Coatings Really Work?
The Truth About Gutter Guards