Hiring a roof cleaning firm: what to ask, VAT, safety and guarantee

Hiring someone to clean a roof sounds simple: a crew climbs up, washes and applies a product. But it is work at height, it has its own VAT rate and, if the firm promises a guarantee, it has to be in writing. This guide says what to ask, what the quote should contain, what the law says about the safety of the people working and about warranty, and what we could not confirm. We do not recommend firms: we only say what to ask for.

Updated 2 November 2026. General information, not legal advice.

The essentials

• Ask for a written quote, after the firm has seen the roof. See the quote checker for the list of what it should contain.
• VAT on cleaning is 23%, not 6%. Cleaning is excluded from the reduced rate.
• Working on the roof is work at height. Portaria 101/96 requires measures against falls from height, collective protection first. Ask how the crew protects itself.
• If the roof is old asbestos-cement, stop. It is not pressure-washed. See the asbestos guide.
• Guarantee: only what is written counts. What it covers, for how long, under what conditions, and who gives it.

What to ask the firm

1. Will you see the roof before giving a price? A phone price knows nothing about area, height or condition.
2. What method? Pressure washing or brush? At what pressure and on what kind of tile? See the guide to methods.
3. What products? Name of the anti-moss and of the protective coating, data sheet and safety data sheet. How many coats and in what weather.
4. What fall protection? Scaffolding, guard rails or lifelines and harnesses. Do not accept “we have done it for years and nobody ever fell”.
5. Where do the water and the product go? And the dirt removed, and any tiles that get broken?
6. What does the price include? Gutters, downpipes, scaffolding, waste removal, travel.
7. What if you find broken tiles? Who tells you, who decides and how much it costs.
8. What guarantee, and what does it cover? See below.
9. Do you have public liability and workplace accident insurance? You can ask for proof.

Safety: why nobody climbs up “just to look”

Portaria 101/96 of 3 April, which sets safety and health rules for temporary or mobile construction sites, has an article on falls from height (article 11): where there is a risk of falling, collective protection must be used if suitable and effective, and individual protection if that is not possible.

A Supreme Court of Justice ruling of 18 April 2007 (appeal 52/07), on a workplace accident, says that work on roofs requires fall measures only when the roof, because of its slope, nature, condition or the weather, presents a real danger of falling, and that this is judged before the worker goes up. A sloped, wet, mossy roof is, as a rule, a roof with real danger.

For you, the owner: do not climb up to “help” or to clean. And if a firm tells you it does not need protection, be wary.

Documents and VAT

• VAT: 23%. The guide to VAT on roof works explains why cleaning is excluded from the 6% rate.
• Permit: maintenance of the roof, which includes cleaning, is exempt from a permit. See the guide to the roof works permit.
• Invoice: ask for an invoice with your tax number (NIF) and a description of the work.

Guarantee: what should be in writing

The most common request is a guarantee of several years on the wash and the coating. It may exist, but it is a promise from the firm or from the maker of the product. We state no period. Ask in writing for:

• who gives the guarantee: the firm, the product maker, or both;
• for how long and from when (completion date);
• what it covers (that moss will not return? that the coating will not flake?) and what it excludes (gutters not maintained, shade, trees, cleaning with harsh products);
• how to claim: whom to write to, within what time, and who pays the call-out;
• the brand and batch of the product applied.

The law already gives rights in a works contract. The Civil Code regulates the works contract (article 1207 onwards): the contractor answers for defects, and the owner must check the work and report defects within 30 days of finding them. For works on buildings there is a five-year period (article 1225). We did not confirm that this period applies to a wash or a tile coating, which are not construction works in the strict sense. See the guide to the warranty on roof works and, if the sum is large, talk to a lawyer.

After the work

• Check the work before paying the balance: gutters clear, no broken tiles, no product left behind.
• Photograph the roof before and after, and keep the quote, the invoice and the product sheet.
• If defects appear, report them in writing and within the deadlines.

What we could not confirm

• Any “normal” guarantee period for roof washing and coating.
• The text of Portaria 101/96 in its current version: we read it through search results, not on the Diário da República, which we could not open directly. Check it before quoting it to others.
• Which authority and exact rules apply to anti-moss and protective products in Portugal. Ask for the safety data sheet.

Sources (read on 2 November 2026)

• Portaria 101/96 of 3 April, article 11 “Quedas em altura”: cited through search results, not read directly on the Diário da República.
• Supreme Court of Justice, ruling of 18-04-2007, appeal 52/07, 4th Section: summary. In Portuguese.
• Civil Code, articles 1207 to 1226, through our guide to the warranty on roof works.
• Our guides on asbestos, VAT and permit, with their own sources.