How To Clean Roof Stains

clean roof stains

Ignore at your peril

It is something that all homeowners can identify with. One of the less glamorous aspects of owning a home; roof maintenance. However boring or tedious it may seem, keeping your roof in tip top condition is in fact one of the best things you can do for your home and will most likely save you from serious long term costs.

Identify roof stains

The first step of getting your roof clear of stains is to identify what the stains are. You may find that these are simply sun damage – in which case you should keep a close eye on them and possibly consider replacing tiles or switching to a different material.

Some stains can be wiped clean (such as animal droppings) and this can be done either professionally or by yourself. Make sure you double check with your hardware store before purchasing any products or machinery that it won’t damage the roof material you’re working with in any way.

The most common form of roof stain however is usually roof mold or algae. These are black stains and usually appear most on roofs made of asphalt shingle.


You may be able to avoid algae stains by using shingles that have been treated with algicide – this can be highly effective for up to 10 year periods. However if you haven’t been able to treat the shingles or if the algicide has worn off, the algae will start to corrode the asphalt and removes the light reflected granules.

Always prepare properly for cleaning your roof stains. This is done best on an overcast day with minimal wind to ensure that the spray you use on the shingles will hit them and stick. Make sure that your gutters are all clear so that they can drain effectively during the spraying.

Cleaning and Protection:

You should use a solution of 50% water and 50% household bleach to clean the roof stains. Always ensure that the bleach is thoroughly diluted to avoid it corroding the shingles and do not use a pressure washer as this can also damage the shingles.

For long term protection, you can also put strips of zinc or copper under the row of shingles closest to the roof peak – this will mean that when it rains some of the molecules in the metals will wash down the roof and kill algae.


If you have a particular type of roof and want to delve a little further, check out These articles are written by real people too and have proven tips and tricks for roof cleaning.