Last updated 9th April, 2020
All you need to know about having your roof cleaned using a pressure washer including costs of materials, costs of labour and time frames.
Roof tiles can suffer from moss or lichen growth, or just a general build up of dirt and pollution over the years. Generally this growth or dirt is just cosmetic and rarely causes any damage to the roof itself. But if a pristine roof is desired, then it is possible to remove moss and grime with a high-pressure hose or you can remove moss manually by using a scraper or brush. Roof cleaning has become popular recently with moss growth on the rise in the UK (caused partly by improvements in air quality as less chemicals such as lead in the air).
Once the moss and dirt has been removed, chemicals to inhibit future moss growth can be sprayed onto the tiles which can keep moss at bay for several years. Typically the job will entail the erection of access equipment to allow safe access onto the roof, covering the ground with a tarpaulin, carry out any minor roof repairs, cleaning the roof with a power washer, treat roof tiles with chemicals, then a final clean up the area and the removal of all waste.
Prior to any pressure washing the roof should be inspected carefully for any damaged or missing tiles or flashing. In fact the entire roof needs to be in pretty good condition otherwise high pressure water will find it's way under the tiles and into the structure of the roof itself. So replace any broken or missing tiles and ensure roof is sound before any pressure washing.
If you own (or can hire) a high pressure hose and can safely access the roof, then you can wash the roof tiles on a DIY basis. After all there are no restrictive laws, permissions or restrictions when it comes to working on roofs in the UK. But be aware that working at heights is dangerous and this job should not be attempted unless you are comfortable working at heights and are clear on how to carry out the work safely. If unsure about any aspect then please leave this job to a professional!
Roofs are incredibly important and if you feel that the moss growth on your roof is hindering water flow than you should indeed get it removed. But be aware that roofs can be damaged during maintenance, especially by inexperienced amateur DIY'ers! Falling through the roof will cost much more than any potential savings that could have been realised by going the DIY route, or by hiring the cheapest unqualified contractors around!
Roofing is not an area in which you should attempt to cut corners on maintenance, do not let anyone on your roof unless you have verified they have the necessary qualifications, experience and insurance - even with something as simple as pressure washing. With some roof tiles high pressure washing can actually wear the tiles prematurely, thereby reducing their effective lifespan, if in doubt consult a roofing professional or the roof tile manufacturer to ensure pressure washing is safe for your roof.
Assuming a typical roof construction such as a 3 bed semi-detached home with no access problems, then you are looking at around £500 to clean the roof using a pressure washer. To remove dirt and moss manually using a scraper and brush will cost around £100 less. These prices include erecting ladders and other safe access equipment, covering flower beds/patio with a tarpaulin, checking roof for damage, pressure washing, treatment using a fungicide chemical, then cleaning of the site and removal of debris and waste material.
Be wary of any prices quoted which are drastically cheaper, this type of roofing work is popular amongst cowboys or unqualified and inexperienced tradesmen. In the UK, Trading Standards have put out several warning notices in the last few years advising home-owners to be wary of cold callers offering roof cleaning services due to a large number of complaints from customers having their roofs damaged and shoddy ineffective work. The prices mentioned on this page are examples of the costs quoted by reputable traders and not dodgy cold callers.
Roof cleaners tend to charge around £200-£250 per day, and depending on how badly the moss has built up it can take anywhere from 4-9 hours to remove the moss using a pressure washer and treat it with chemicals to prevent future build up.
Here are a few average costs for hiring someone to pressure wash your roof clean:
|House Type||Roof Type||Avg. Cost||Duration|
|Terraced||Not Applicable||£450||4-6 hours|
|Semi-detached||Gable Roof||£450||4-6 hours|
|Detached||Gable Roof||£550||5-7 hours|
|Semi-detached||Hip Roof||£600||6-8 hours|
|Detached||Hip Roof||£850||7-9 hours|
Individual costs for hiring a tradesman to pressure wash the roof of a 2-storey semi-detached house with a hip roof and easy access - Total Cost: £600