The short answer
A roof cleaner's charge depends on the roof, so it is priced after a survey rather than off a rate card. Area, steepness, covering, the thickness of the growth, access and anything else the survey finds all move the total. Ask any firm for one written total, and ask whether VAT and access are in it.
What sets the total for a roof clean
Cleaning is a labour job, so the price follows the time the work takes and the equipment needed to do it safely. The first factor is size. A wide, low roof has more tiles to treat, and a tall one with several pitches takes longer to move around. Steepness comes next, because a steep slope calls for roof ladders or a platform and slows every task.
Covering matters too. Concrete, clay and slate tolerate different treatments, and an old tile that has lost its surface needs a gentler hand than a recent one. The amount of growth is the third driver: a film of algae is quick to treat, while moss built up in thick mats, with lichen beneath, needs more time and care.
Finally come the extras around the roof, which are easy to miss from the pavement. Gutters packed with moss, a blocked valley, an overgrown flat section or a conservatory roof beside the main slope can all add work. None of these show clearly in a photograph taken from the road, which is why the figure waits for the survey, and why a number quoted without one is a guess.
Access, scaffold and VAT
Reaching the roof can move the total a long way. A single-storey slope can be reached from a ladder. A house with a long run of high eaves may need a tower or full scaffolding, and that brings its own cost and, over the public highway, a licence from the highway authority. When scaffold is part of the job, it sits inside the written total, so it never arrives as a surprise.
Always ask what a quote includes. Check whether access is in the price, whether the gutters are cleared, whether moss and debris are taken away and whether VAT is added. The standard VAT rate is 20 per cent, and a figure shown without it will look lower than the final bill, so compare like with like.
It is also worth asking how the roof will be treated. A firm that proposes jet washing the tiles is describing a method Marley does not recommend, because forceful water can wear away the tile face. A quote that names a gentler method describes a better job, even if the day on site seems less dramatic.
Comparing quotes sensibly
Citizens Advice recommends collecting at least three written quotes before you settle on a trader. That works for a roof clean too, provided every quote describes the same job, with the same slopes, gutters and clear-up. A price for treating the front slope only is not comparable with a price for the whole roof and the gutters.
Lower is not always better value. A very low price may mean a quick blast with a pressure lance, a thin coat of treatment or no clearing of the gutters. A higher price may include proper access and a roofer's check of the tiles. Judge each by what the firm says it will actually do and how it will reach the roof.
A survey should produce photographs of what was found, a plain-language explanation and a written total. If a firm will not look at the roof before naming a number, treat that number with caution, and if one promises a miracle finish, ask what the conditions are.
Our answer on whether cleaning is worth it covers the other side of the decision.
What happens at a survey
A survey for a roof clean starts from the ground and the loft. We look at the covering from several angles, check the tiles and ridge, inspect the valleys and gutters, and look inside the loft for damp. Where safe access allows, we go onto the roof for a closer look. You see the photographs afterwards.
From that we propose the gentlest method that does the job, and describe what will happen over the following weeks as the treatment works. If the survey finds something that needs repair, you are told, and the repair is kept apart from the clean so you can see what is a priority.
The written price follows the survey, covering the whole job as a single total. You can use it as the basis for comparing other firms. The roof cleaning and moss removal page lists the methods, and the guide to roof cleaning methods compared helps you question anyone else you consult.
If you would like a view before booking, send a few photographs of the roof and gutters and mention the type of house.
