How to Choose a Roof Cleaning Company Without Getting Stung

The checks to make before anyone visits

Confirm public liability insurance and ask for the certificate, not a verbal assurance. Work at height on someone else's property without adequate cover is a serious risk to you as the homeowner. A figure of £5,000,000 is a reasonable expectation for this trade.

Look for a verifiable trading identity: a real address, a landline or long-standing mobile number, a website with genuine project photographs rather than stock images, and reviews across more than one platform. Consistent reviews over several years matter far more than a burst of five-star ratings in one month.

• Public liability insurance certificate, sighted
• Verifiable address and contact details
• Genuine before-and-after photographs of their own work
• Reviews spread over time and across platforms
• Written quotation, not a verbal figure

The questions that reveal competence

Ask what method they will use on your specific roof and why. The answer you want involves manual removal and a biocide, and an explanation of why pressure washing is inappropriate for tiles. If the answer is 'we'll jet wash it', you have your information.

Ask what happens to the debris, whether gutters will be cleared afterwards, how they will access the roof safely, what protection goes down for planting and paths, and what happens if a tile breaks during the work. Competent contractors answer all five without hesitation because they think about them every day.

What a proper quotation contains

It should itemise the scope: inspection, manual moss removal by elevation, valley and gutter clearance, biocide application, debris removal, and any tile repairs identified. It should state the access method, the price basis — fixed or variable — and payment terms.

Deposits should be modest or absent for a job of this size. Requests for large upfront payments, or for cash only, are a well-known warning sign in this trade. Reputable contractors invoice on completion.

Red flags

The clearest is the unsolicited doorstep approach: someone 'working in the area' who has 'noticed a problem with your roof'. This is the standard opening of roofing fraud in the UK, and the correct response is to decline and seek your own quotes.

Others include high-pressure sales with a today-only price, refusal to provide anything in writing, quotes given without seeing the property or photographs, claims that moss is causing structural failure requiring immediate work, and any promise of a lifetime guarantee against regrowth, which no biocide can deliver.

• Unsolicited doorstep or cold-call approaches
• 'Today only' pricing or pressure to decide immediately
• No written quotation or insurance details
• Quoting without seeing the roof or clear photographs
• Promises of permanent, lifetime moss prevention
• Cash-only demands or large upfront deposits

Comparing quotes fairly

Get three quotes and compare scope rather than headline price. One quote at £450 covering scraping only and one at £750 covering scraping, biocide, valley clearance and gutter clearing are not the same product, and the second is usually the better value.

Ask each contractor to confirm in writing that no pressure washing will be used on the tiles. That single line filters out the majority of the risk in this trade, and any firm that hesitates to put it in writing has told you something important.

The bottom line

If you only do two things from this guide, ask to see the insurance certificate and ask for written confirmation that no pressure washing will be used on the tiles. Between them, those two requests filter out most of the genuine risk in this trade, and neither is remotely unreasonable to ask of a professional contractor.

Beyond that, trust the quality of the conversation. Someone who explains why your roof does or does not need work, sets realistic expectations about how a biocide develops over weeks, and tells you honestly when the answer is to wait another two years is the sort of contractor worth keeping the number of. That is the standard we try to hold ourselves to, and it is a fair standard to hold anyone else to as well.

Frequently asked questions