Cost of Roof Cleaning using a Pressure Washer

All you need to know about having your roof cleaned using a pressure washer including costs of materials, costs of labour and time frames.

pressure washing roof clean

What the job entails

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.

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Roof Pressure Washing Cost

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


Cost Breakdown

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

35%

Materials
£210

40%

Tradesmen
£240

25%

Access Tower
£150

FAQ's

Yes the cleaning of roof moss using a high pressure hose will indeed be messy with moss flying everywhere! But a professional company will use tarpaulins as protection and remove all debris as part of the job -so don't let this put you off!
Professional companies will use pressure which is too low to damage your roof and will also check the condition of the roof tiles beforehand. However, many tile manufacturers do not recommend using pressure washing as this can damage roof tiles causing premature wear, so this has to be checked beforehand.
Yes, chemical treatments such as Benzalkonium chloride are cheap and widely available. These biocides will kill moss and algae then prevent moss growth for many years. A little goes a long way with most of these compounds being diluted 1:20 with water. However, be aware that protective clothing, gloves, googles and mask are required if spraying as part of a DIY project. In most cases, once moss etc has been removed and the roof treated, you only need to treat the roof every 3 years or so, further cleaning either manual or pressure washing should not be necessary except in areas with very high pollution.
Manual cleaning obviously involves more elbow grease, plus complete access to all areas of the roof, it is less messy too. But pressure washing is easier and often faster, plus the washer itself gives a much greater reach for easier access. But on certain types of roof tiles, you will need to clean the roof tiles manually as pressure washing will cause damage/wear to the tiles - so check with the tile manufacturer before carrying out any cleaning on the roof using a high pressure hose.