Roof Cleaning Cost – Roof Moss Removal Cost

roof cleaning costA clean roof not only improves the look of your home, it also gets rids of any accumulated moss and lichen that can cause damage to the structure of the roof in the long term.  It is a quick and easy process and can soon have your roof looking as good as new.

Before you decide to go ahead and arrange for your roof to be cleaned you need to do some research on roof cleaning cost and also to make sure that you are getting the job done to the highest standards.  So that you know you are going to get a top roof cleaning job done we have created the following tips to help:

What is involved in roof cleaning?

The main aim of roof cleaning is to remove all the mold, algae, moss, lichen and any other accumulated debris from the surface of the roof.  In metal roofs it will remove any signs of oxidation.  Not only does cleaning improve the look of the roof it also increases the lifespan and improves the functionality of the roof structure.   Most of the build up of unwanted materials on the roof appears on the north and west sides of the house where it is exposed to less sunlight.  The roof’s ability to absorb heat from the sun is affected by the presence of lichens and moss, etc., and can therefore act to increase the costs of heating the home.

The most commonly used solution for roof cleaning is either sodium percarbonate solution or bleach.  However, there are many cleaning products available and professional roof cleaners often have their own preferred products.  ARMA (The Asphalt Roofing Manufacturers Association) recommends that a solution of 50/50 water and 12.5% sodium hypochlorite (the same chlorine that is used in swimming pools)  be used to clear moss and algae from asphalt roofing.  Zinc sulfate applied annually can reduce the regrowth as can the installation of zinc strips near the peak of the roof.

Roof Types & Cleaning

There is a wide variety of different roof types and roofing materials and you will need to ensure that you use the correct type of roof cleaning solutions and methods for your own type of roof.


Asphalt shingles create a protective roof when applied in layers over the roof.  They provide resistance to the elements and is one of the most common types of roof we see.  The way the shingles are layered and the fact that they are breakable means that you need to pay special attention to maintaining the roof and take care when cleaning.  If a shingle breaks there is an immediate lack of protection in the structure of the roof.  In order to clean an asphalt roof safely you will need to maintain the water pressure at that similar to a garden hose, or no more than 30 psi.

There are many suggestions of how to clean an asphalt roof and also a wide variety of cleaning products available.  However, most of the DIY solutions that can be formulated at home have drawbacks including relying very heavily on bleach.  Although this will clean the shingles it will also damage vegetation underneath and corrode metal fixings.  It is always safest to use a properly formulated asphalt roof cleaning product.

Ceramic Tile

If you have a Spanish style home, you are likely to have a ceramic tile roof.  This type of tiles is less sensitive to water pressure than their asphalt counterparts and are resistant to high pressure cleaning.  However, you will still need to take a certain amount of care with the psi settings on the power washer as extremes of pressure can lead to damage and cracking in the ceramic roof tiles causing additional expense to repair the roof.

Clay Tile

Clay tiles are popular and common in both the Southern and Southwest USA and give a similar look and feel to ceramic tiles. They are a great choice for warmer areas because they help to insulate against the heat and keep the house cool. However, as far as cleaning goes it is important to remember that the clay tiles are not formed in the same was as the ceramic tiles and are a combination of clay and sand.  You have to adjust your cleaning method to accommodate the fact that clay tiles are more porous and more prone to breaking under higher water pressures so ensure that you keep the water pressures low.

Concrete Tile

Concrete tiles are the tile of choice in more temperate regions such as the Pacific Northwestern areas of the US.  Concrete tiles combine standard and asphalt tiles which sets them apart from other roof tile types.  The tiles are formed with a sandy finished over a porous concrete base.  The finish wears off over time and because of this these tiles can be easily damaged by any form of pressure washing technique.


Slate tiles are a natural roofing material and are extremely delicate.  The tiling technique for slate is that they are not layered, and they provide a sleek and smooth look to a roof.  They are very hard wearing and can last anywhere from 75 to 200 years.  Because of this they cost a lot more than other tiles and are mostly used on luxury, top of the range homes.  Slate tiles do not respond well to any kind of pressure washing or any of the formulated cleaners which can both damage the roof, causing splitting and separation of the tiles.


Metal is a low maintenance roofing solution which is becoming more and more popular.  It is incredibly low maintenance and easy to clean.  Installation is the main challenge for this roof and you will need an experienced contractor, however once installed it is a lightweight and environmentally friendly roofing solution.  These metal roofs also retain their looks well, and although the color can fade over time, simply painting the roof returns it to an as-new condition.

Reasons To Clean Your Roof

roof cleaning pricesProbably the most obvious reason to have your roof cleaned is that it improves the look of the roof and the overall esthetic of your home.  In addition it helps maintain the value of the property and makes sure that the roof does not break down and need replacing more quickly than necessary.  If a roof is not kept clean the tiles will start to break down quite quickly.  The algae growth not only looks unpleasant, it can also feed on some of the components of the tiles, it can create space between shingles or tiles, allowing water ingress which can damage wooden structures and décor inside the property.

Although it obviously costs money to clean your roof the cost will be offset by the fact that the overall lifespan of the roof is increased and you will save money on repairs to your roof or even a replacement roof.  The cost will therefore pay for itself over time.

Roof Cleaning Process

Step 1: Roof Analysis

The first step is to inspect the roof.  This should be a thorough inspection so that you can ascertain the type of roof and the nature of the cleaning problem.  A good first analysis helps to avoid using incorrect cleaning agents or high water pressures which could ultimately cause permanent damage to the roof.  The best advice is to hire a professional roof cleaning firm to get first-rate results.

Step 2: Cleaning the roof

After you have completed the first step and discovered the type of roofing you need to clean, you need to use the appropriate cleaning methods:

  • Roof tiles are cleaned with hot water directed onto the roof via a pressure cleaner. The water then washes away all of the dirt, algae and moss.  If there is a lot of debris to be removed an extra cleaning product may be added..
  • Roofing sheets are cleaned in the same way as roof files. The sheets are suited to high-pressure cleaning because of their strong and sturdy nature.
  • Slate roof tiles are a lot more fragile so you need to take care to avoid damaging them. A lower water pressure is therefore needed to clean these roofs..
  • Thatched roofs do not require any sort of water or chemical based cleaning, instead any moss, algae or other unwanted debris is removed by shaving off a thin layer of the roof..

Step 3: Finish and protect

Once the roof is thoroughly cleaned, a disinfectant is squirted on to the tiles to keep any regrowth at bay and maintain the cleanliness of the roof.  You can also choose to use a roof coating to further protect the property which involves spraying a thin layer of product directly on the roof.  This is either transparent or you can choose a color if you prefer.  The roof will be better protected as a result and will also stay looking as good as new for longer.

Cost to Clean a Roof by Pressure Washing

This gives an example of the cost for a thorough cleaning of your roof tiles using a pressure washer.  This was last updated in 2018.

A typical roof cleaning work schedule would look something like this:

  • Access equipment – this would need to be erected to gain access to the roof and includes equipment like ladders, specialist roof ladders, access towers and so on.
  • Ground protection – the ground beneath would be covered with a tarpaulin to protect it from damage.
  • The roof is completely cleaned using a power washer.
  • Roof inspection – the roof should be checked for any damage, broken tiles replaced and any major repairs carried out as needed.
  • Roof treatment – the use of a chemical to inhibit moss growth should be used.
  • Making good – the removal of any waste material and access equipment used.

The average cost to pressure wash a roof is currently around  £480.00 +vat on average.

Price to Remove Roof Moss Manually With Scraper and Brush

If your roof is not suited to power cleaning there is a manual process for removing the moss.  The advantage of this is that it eliminates the risk of high-pressure water damage to the roof.  The process for manually removing moss is:

  • Installing all the ladders and access equipment to gain access to the roof.
  • Placement of protective sheeting across any flower beds/patio or other structures beneath the roof.
  • Manual moss removal using a scraper.
  • Cleaning the roof by brushing away any residual dust.
  • Making sure the roof is not damaged, carrying out any necessary repairs.
  • Application of a fungicidal roof treatment to delay regrowth.

Leaving the site clean, tidy and free from waste materials.