Roof cleaning & moss removal · A focused guide
How should cleaning be assessed on a slate roof with old repairs?
Published by Big Ben Roofing Ltd
Ask for the existing slate covering and earlier repairs to be considered before the cleaning method is selected. Growth can draw attention to a slope without explaining the condition of fixings, repair pieces or junctions beneath it. Share the repair history and identify any slipped or cracked slates already visible. The proposal should distinguish inspection, cleaning and separate repairs, with suitable access planned; do not walk the slate roof or try a test scrape yourself.
Show repairs as well as growth
Provide existing photographs or invoices for patched areas, metal repair pieces or a previously renewed section. State whether the concern is general appearance, repeated debris or a new change in the covering. A cleaner needs context for the areas that may respond differently to disturbance. If the slate product or repair material is uncertain, record that instead of choosing a method intended for a different covering.
Agree what happens when a defect is found
Ask how the contractor will record a loose or damaged component before continuing nearby, and who can authorise any roofing work. Cleaning should not conceal an unresolved repair discussion inside a broad service description. Establish whether the quoted inspection can assess the relevant connections or leaves some areas unconfirmed. HSE’s fragile-surface guidance is relevant to access planning, even when the intended task is described as surface maintenance.
Useful details to record
- Mention slipped slates and earlier patched areas.
- Share repair records and material details already held.
- Separate cosmetic aims from drainage or leak concerns.
- Agree a process for documenting defects before further work.
Use information already available from indoors or ground level. Do not climb onto the roof or disturb materials to complete this checklist.
Can a cleaning company promise all old slate repairs will stay unaffected?
A distant image cannot establish every repair’s condition. Ask what the pre-work assessment covers, how vulnerable details are treated and how unexpected defects will be reported, rather than relying on an unrestricted assurance about retained repairs.
Background reading
General guidance helps frame the questions. The cause, suitable materials and scope depend on inspection of the particular roof.
Related questions
Should cracked or slipped tiles be assessed before roof cleaning?
Separate visible covering defects from a cleaning brief and agree how existing damage will be recorded before a roof surface is disturbed.
Does visible moss need removing if the roof is not leaking?
Separate appearance, drainage and roof condition when deciding whether visible moss calls for cleaning or a more limited maintenance task.
Discuss what you have noticed
Include your postcode, the affected roof section and when the concern appears. The team will review the enquiry and confirm the next step, scope and availability.
Request a roofing assessment