How to avoid costly damaged roofs

Claire Kendall, Trading Standards

Local Trading Standards Services regularly receive complaints about various unsatisfactory home improvement work. A growing area of concern is with roof cleaning services, including jet washing.

Experts and roof tile manufacturers have provided Trading Standards officers with advice to highlight some of the misconceptions associated with these services.


Different roof covering materials have different lifespans, but it is generally accepted that the majority of UK manufactured tiles are fit for purpose for at least 60 years.

You may see lichens, mould and similar growths on your roof, and although you might not like the look of them, they are not generally detrimental to the lifespan of your roof tiles.

If the growths are interfering with the free flow of rainwater from your roof, you may need to take some action by cleaning with a biocide, wire brush or a low pressure wash.

Pressure washing

Roofing experts warn that roof tiles should not be subjected to high-pressure washing or jet washing for many reasons. These include:

  • it will remove the granular surface finish and potentially damage the tile. This process followed by a surface treatment application will invalidate any tile manufacturer’s guarantee.
  • interlocking roof tiles are not designed to be walked on. Foot traffic can cause these interlocks to break, opening the roof up to leaks.
  • inappropriate pressure washing can potentially force water up between the tiles and roofing felt into the roof space. Bedded mortar and flashings can also be blasted off using this method, which could lead to a repair bill for you.


Cold callers are charging consumers around Milton Keynes up to £800 for this service. If the roof is damaged by the process, the final cost may be a lot more.


It is also a very messy business and residents have made aware Trading Standards aware of neighbourhood issues. This includes damage to caused to cars and moss on the neighbours driveways etc.

Make sure you

  • Say not to cold calling traders. Reputable traders do not generally have time for cold calling.
  • Speak to a legitimate company about any concerns relating to your roof.
  • Check out their address on their website, then view it on Google maps to see where they are based. If their post code is the middle of a supermarket car park, you might want to try another trader!
  • Check their membership of trader approval schemes, there are lots of these schemes so check to see what help you might get if something goes wrong, or use the Trading Standards Approved local scheme

If you are aware of one of these companies operating in your area please call 03454 040506 to report them.