# Roof cleaning: when it is needed, how it is done and what to ask > Moss, lichen and full gutters: what the sources say, what it costs and what to ask before you hire. Three short guides. - Page: https://telhadoseguro.pt/en/roof-cleaning - Language: English - Updated: 2026-11-03 ## Summary - APICER and CTCV recommend a yearly routine of roof inspection and cleaning. - Moss, weeds and leaves can block drainage, move tiles and hold water. - On old asbestos-cement roofs, do not pressure-wash or scrub. - Cleaning is not repair: broken tiles need repair. A roof with moss, lichen and piled-up leaves is not only a question of looks. The technical guide of the Portuguese ceramics association (APICER) and the Ceramics and Glass Technology Centre (CTCV) says roof faults come mostly from a total lack of maintenance, and recommends a yearly routine of inspection and cleaning. This section explains what cleaning a roof means, when it is needed, what it costs according to the sources we found, and what to ask whoever does the work. We do not clean roofs: we give information, with sources. *Updated 2 November 2026.* ## The essentials - **Cleaning the roof is maintenance.** The APICER and CTCV guide asks for inspection and cleaning once a year, and drainage (gutter) maintenance twice a year. - **Moss, weeds and leaves can block the water.** The same guide describes vegetation that blocks drainage, moves and breaks tiles and holds water, especially at the eaves and in the gutters. - **Asbestos-cement roof: do not pressure-wash or scrub.** Any handling can release fibres. See the [asbestos guide](https://telhadoseguro.pt/en/guides/asbestos-roof-law-removal). - **Cleaning is not repair.** If tiles are broken or displaced, cleaning does not stop a leak. - **Working on a roof is work at height.** Falls are the main risk. Do not climb up without protection; hire people who work with their own safety equipment. ## When cleaning is needed Signs that need attention, according to the APICER and CTCV guide: **vegetation growing on the roof**, **gutters and eaves full of soil and leaves**, and **water that no longer runs off as it should**. In all three cases the guide treats the situation as a warning sign that may need a deeper intervention than a simple wash. Moss and lichen alone, with no broken tiles and no leaks, are mostly a matter of upkeep and looks. DECO Proteste, the consumer association, said in a 2022 article that moss damages ceramic and slate tiles and lets water in more easily. ## Where to start: three questions 1. **What roof do I have?** Ceramic or concrete tile, slate, asbestos-cement sheet, sandwich panel? If it is old asbestos-cement, stop here and read the asbestos guide. If you do not know, do not climb up; ask someone who does to look from the ground or from scaffolding. 2. **Is the problem only on the surface?** Moss and dirt are one thing. Broken tiles, rotten battens, loose flashings and holed gutters are another, and need repair. The [guide to leaks](https://telhadoseguro.pt/en/guides/roof-leak-causes) helps tell them apart. 3. **Who will work, and with what protection?** See the guide on [hiring a cleaning firm](https://telhadoseguro.pt/en/roof-cleaning/contractor): documents, VAT, safety and what the quote should say. ## The guides in this section - [How a roof is cleaned: methods, risks and when not to](https://telhadoseguro.pt/en/roof-cleaning/methods) - [What it costs to clean a roof: what we found](https://telhadoseguro.pt/en/roof-cleaning/price) - [Hiring a roof cleaning firm: what to ask, VAT and safety](https://telhadoseguro.pt/en/roof-cleaning/contractor) ## Other guides that overlap - [Roof checklist before winter](https://telhadoseguro.pt/en/guides/roof-checklist-before-winter) - [VAT on roof works](https://telhadoseguro.pt/en/guides/roof-works-vat): cleaning is outside the 6% rate. - [Warranty on roof works](https://telhadoseguro.pt/en/guides/roof-works-warranty) - [Quote checker](https://telhadoseguro.pt/en/roof-quote-checker) and [check a contractor](https://telhadoseguro.pt/en/roofing-contractor-check) ## What we could not confirm - **Official cleaning prices.** There is no state table or trade-association table we could read. The figures we quote come from a private portal and are in the price guide. - **One "right" method or pressure for every roof.** The APICER and CTCV guide gives none. The DECO Proteste article is consumer advice, not a standard. - **How many years a protective treatment lasts.** We found no independent source. Ask the product maker for the data sheet. ## Sources (read on 2 November 2026) - APICER and CTCV, [Guia para Projeto e Aplicação de Telhas Cerâmicas](https://www.apicer.pt/apicer/media/5c06bd0e8d436.pdf), 2nd edition, 2018 (section 7.4.2, page 95: yearly inspection and cleaning; case 6, page 102: parasitic vegetation). In Portuguese. - DECO Proteste, [Máquinas de limpeza de alta pressão: dicas para trabalhos de manutenção da casa](https://www.deco.proteste.pt/casa-energia/manutencao-casa/dicas/maquinas-limpeza-alta-pressao-dicas-trabalhos-manutencao-casa), 3 February 2022. In Portuguese. - Our guides on [asbestos](https://telhadoseguro.pt/en/guides/asbestos-roof-law-removal) and [VAT](https://telhadoseguro.pt/en/guides/roof-works-vat), with their own sources. ## FAQ ### Can I wash the roof myself? We do not advise it. It is work at height and the main risk is a fall. If the roof is old asbestos-cement, never: any handling can release asbestos fibres. ### How often should a roof be cleaned? The APICER and CTCV guide asks for inspection and cleaning once a year, and drainage maintenance twice a year. ### Is cleaning charged at 6% VAT? No. Cleaning is excluded from the reduced rate and carries 23%. --- Source: https://telhadoseguro.pt/en/roof-cleaning. Independent information, not legal or tax advice.