Are you thinking of having your roof tiles jet done? Think again.

As stated by several roof tile manufacturers and the UK's Trading Standards organization, pressure washers Tin damage roof tiles, strip the surface granules from the tiles and SHORTEN tile life expectancy. There is too a gamble of flooding to the loft infinite.

Read more than about why pressure washing a roof is a very stupid thing to do

Roof cleaning tin can be achieved by manually removing any excess moss and then applying the right chemicals to the tiles. This arroyo doesn't involve any water (no mess!) and won't damage the tiles. Whatever individual tiles that are damaged during this process can be replaced cheaply as roof tiles are not that plush to supercede if all the scaffold and access equipment is already in place.

It does involve using some chemicals (such equally Moisture and Forget) and also a good dose of patience!

Roof Cleaning by Using the Correct Chemicals

One of the virtually gentle notwithstanding effective ways to remove roof moss and clean the roof is past way of scraping. A normal 9″ trowel is suitable, if your roofing contractor chooses a dry day any moss will flake off the roof much easier and in that location won't be any scratch marks on the tiles. This approach is recommended past Forticrete who are 1 of several roof tile producers in the United kingdom.

If you are concerned nigh scuff marks to the tiles then a safe scraper and stiff brush can be used. Remember – with this method there is no damage to the tiles and no flood run a risk, unlike other roof cleaning methods such as high-powered pressure washing.

Look at the photo below, the moss was removed with nothing more a trowel and a hand castor, the deviation compared to the mossy section of roof is striking.

Roof cleaning doesn't need to involve power jet washing.

This photograph was even taken before any chemicals were practical – what a difference! As yous can see, there is no damage to the tiles, no scratch marks and the tiles accept not been dislodged by the process.

Roof cleaning

And so Why Utilize Chemicals?

If yous apply a fungicide/moss killer after the moss has been scraped off, it will soak into the tile and more than chiefly into the overlaps of the tiles and kill off whatever tiny moss spores. Information technology will also kill off lichen and other organic growth on the tiles. This roof cleaning process can take some fourth dimension after the excess moss is initially removed only in that location is no harm to the surface of the tile.

The awarding of roof cleaning chemicals will also forbid the moss from growing back for several years.

Every bit a bonus, this chemical will as well kill lichen, so those black marks on the tiles volition fade abroad a few weeks after the handling.

Which Chemicals are Recommended?

RoofCoatingScam recommends the following moss handling chemical for roof tiles, paths, patios, fence panels, driveways and virtually hard surfaces:

No Pressure Washing. No Flood Risk. No Expensive (and Useless) Roof Coatings

Equally stated in other pages, roof coatings are oft an expensive and brusque term approach to roof renovation/roof cleaning. There is a real flood risk, the coatings often look terrible after a few years and they being mis-sold by many many companies in the Britain.

The transmission approach to removing moss and applying a chemical may be considered an old fashioned roof cleaning method but it is time-proven and yous certainly won't accept to worry nearly paint peeling off the tiles.

Did I mention that manually removing the moss/applying a fungicide is oftentimes the cheapest cleaning method?

Expect to pay around £500 for a semi-discrete house in Southern England. Compare that to £2000 for a roof cleaning and coating.

Moss removal from rood
Moss removed past way of scraping on the right side of the roof
Moss removal in progress
Moss removal, past hand, in progress.
Moss removed from roof by way of scraping
Moss removed from roof by way of scraping

How Long Does the Moss Killer Last?

Assuming that the roof isn't under tree cover, the moss shouldn't grow back for about iii years, after 4 years there will be lite growth.

For this reason, the homeowner should instruct a roofing visitor to re-use the chemical every 3 years, thus preventing any moss growth and keeping the roof looking clean.

Moss killing chemicals are non expensive, await to pay around £30 for enough to care for a semi-detached property. A backpack sprayer costs around £25 and the work takes around an hr.

If you lot purchase a more expensive haversack sprayer (Hozelock 12 or sixteen litre) and then you volition find they have a very long reach, nearly 6 metres! That is enough to reach the top of the roof from access towers erected to gutter peak.

So once the moss is initially removed nobody e'er needs to go on the roof over again. This reduces the amount of foot traffic on the roof tiles. Remove the moss once, re-employ the chemicals from gutter height with a sprayer every few years – unproblematic and cost-effective!

This type of work is oftentimes carried out by traditional roofing contractors, although few roof cleaning/blanket companies recommend this approach as it doesn't involve pressure washers and expensive roof coatings/sealants.

It is possible to complete a roof cleaning project without pressure washing, but the chemicals practise take a little time to work. Remember: the "dirt" you see on a roof is usually moss and lichen which can exist treated and prevented with chemicals.

Can a Moss Killer exist Practical Before the Moss is Removed?

This is a common question, tin/should a moss killing chemical exist practical to the roof earlier the moss is removed?

The answer is no.

First, you would need much more of the chemical every bit the moss would soak it upwards.

2d, thick layers of moss will forestall the chemical from soaking into the tile/overlaps.

Third, if you lot were thinking of applying the chemical instead of manually removing the moss with a scraper, then you lot would have a big problem – the dead moss would gradually launder down into the gutters and block them. It could take months if not years for all the moss to launder off the roof. Your gutters would need frequent cleaning and fifty-fifty and then they are still likely to get blocked.

Advice From Tile Manufacturers

Marley Eternit, one of the  largest roof tile manufacturers in the United kingdom of great britain and northern ireland responded to an e-mail enquiry nearly how to make clean their popular "Double Roman" blazon roof tile with the post-obit statement:

We DO NOT recommend pressure washing your roof covering.

Forticrete, which manufacturers a variety of concrete tiles for the UK market responded to a similar request with the post-obit statements:

Removal of moss should exist washed manually off proper roof access equipment to protect the tiles and operators.
This should be done with a scraper and stiff hand castor.

They added:

Ability washing the tiles will remove fines in the concrete which will affect the lifespan of the tiles…. Equally a manufacturer of physical roof tiles nosotros would not abet ability washing or recoating tiles every bit this would invalidate any guarantee.

You can read more guidance from tile manufacturers, regime bodies and consumer protection agencies here.

Which Chemicals are Best?

Equally nosotros have previously stated, in most cases moss will not impairment the roof tiles just tin block gutters and drainage points. On certain roofs, such as those with a very shallow pitch, moss tin can potentially reduce the flow of water off the roof.

If this is the example (and very few roofs endure from this upshot) then gently removing the excess moss via traditional methods and treating the tiles/remaining moss with a fungicide is the best pick.

Try any of the moss killers listed hither, they can exist used on tiles, patios and driveways etc. I have used all of them previously.

Equally full general advice: RoofCoatingScam does not recommend regular roof cleaning just for the sake of improving the advent of the roof. Foot traffic can damage roof tiles and then we only recommend roof cleaning/de-mossing when it is absolutely necessary, ie when the moss is preventing water from draining off the roof.

Farther Reading

Did you similar this article? Why not "like" us on Facebook and then effort one of the post-obit links:

Is it safe to force per unit area launder a roof? (Communication directly from tile manufacturers)

Practise concrete tiles need to exist re-sealed?

Roof blanket scammers found guilty in £2.4million scam (wow!)

Yet some other confidence in the roof coating industry

Are thermal roof coatings the biggest scam in the roofing manufacture?

Cost and price guides for roofing related work tin be institute at Roofer's Rates

(Page updated Feb 2022)