Can Roof Cleaning Void a Tile Warranty?

What a tile warranty covers

Most tile warranties come from the manufacturer, not the roofer. They typically cover the tile against manufacturing faults, such as surface failure or loss of strength, for a stated period. They rarely cover problems caused after the tile leaves the factory, including poor fitting, damage by people walking on the roof, or improper cleaning. Some also require the roof to be maintained in a particular way, and some are tied to the original installation by an approved fitter. The wording differs from one maker to the next, and from one product range to another, so do not assume yours matches a neighbour's.

How cleaning can cause a breach

The common worry is pressure washing. A powerful jet can strip the protective surface layer of a concrete tile, erode the face of a soft clay tile and force water under the laps. Our guide to whether pressure washing damages roof tiles explains the damage. Strong acids, bleach and some household chemicals can discolour or weaken tiles. Scraping and wire brushing can scratch coatings. If a maker finds damage of that kind, it may refuse a claim on the grounds that the tile was harmed after installation.

What to look for in the wording

Check three things. First, whether the warranty names cleaning methods that are excluded, or says anything about pressure washing and chemical treatments. Second, whether it requires you to use an approved method, product or contractor, or to keep records of maintenance. Third, how long it runs and whether it has already expired, as an old roof may be out of warranty and the question moot. If you cannot find the document, contact the maker with the tile name and the date of installation. Our answer on whether cleaning a roof adds value covers another reason to keep the paperwork.

Safe approaches

Methods that avoid abrasion and high pressure are the least likely to cause trouble. Hand removal of moss with a soft tool, followed by a suitable biocide applied at low pressure, is generally gentle on the tile surface. Our guide to moss removal methods compared sets out the choices. Whichever you choose, ask the contractor how they protect the tile surface and ask for the method and product names in writing, so you can show them to the maker if asked.

Coatings and treatments

Some maker warranties say something about applied coatings, because a coating can change how water leaves the tile. If you are thinking of one, our guide to roof coatings on tiled roofs explains the pros and cons. Check the warranty before applying one, not after.

Roofer workmanship is separate

Your tile warranty is not the same as the roofer's guarantee. Our written guarantee runs for ten years and covers the work we carry out. It is a promise from us about workmanship, with no insurer behind it, and it sits alongside the maker's product warranty without replacing it. Keep both documents together.

When the warranty has already run out

Many roofs old enough to need cleaning are also old enough to be out of warranty, because guarantees on concrete and clay tiles run for a set number of years from the date of manufacture or installation. In that case a warranty cannot be voided, and the practical question becomes what the cleaning does to the tiles. An elderly tile with a worn face needs gentler treatment, not harsher, and the cleaner should be told its age before choosing a method. A survey before cleaning shows whether the surface is sound or crumbling, and whether cleaning will help or whether repairs should come first.

Records worth keeping

Keep the original warranty, the invoice for the roof, the tile name and batch numbers if they were recorded, and anything from the cleaner: the date, the method, the product used and photographs of the roof before and after. If a maker ever questions a claim, a clear record of a gentle method on a sound roof is much better than a recollection. Put them in one folder with the house documents, because a buyer or surveyor may ask for them when you sell.

What we do

Tell us the tile make if you know it, and we will help you read the warranty and choose a method that fits. The free survey photographs the tile surface before anything is touched, so the roof's condition is on record. The wider range is on our roof cleaning page.