Slate roofs are an attractive feature of many older British buildings but their dark colour means that bird droppings can be very obvious, even from a distance. Although bird droppings on external surfaces such as a slate roof are unlikely to cause a health hazard, removing them is an important part of general roof maintenance. Droppings provide the nutrients that encourage the growth of moss and lichen which can block gutters and make your roof look unsightly.
Ensure you can access the roof area safely. If the roof is low, for example on a porch or single-storey extension, an ordinary ladder may be sufficient, but if it’s higher you may need to consider using scaffolding and a specialised roof ladder. Do not add extra risk to the job by attempting to clean your roof in windy weather.
Fill a bucket with warm water and a squirt of washing-up liquid. Carry it up to the roof and prop it in a stable place where it cannot slip or fall.
Begin cleaning the slates with the sponge,wearing the gloves. Start from the roof line and work downwards. You should be able to remove most bird droppings using this method, although more stubborn marks may require a weak bleach solution. Exchange the dirty water in your bucket for fresh water every so often.
Rinse off the roof using a hose or clean water from a bucket. Chris Thomas from the Tiled Roof Consultancy in Surrey, recommends directing the water from above rather than below if you’re using a pressure hose. This will avoid blasting dirt and debris under tiles and into the underfelt beneath.
If droppings are a problem because birds are sleeping or frequently perching in a particular place, such as your chimney, consider installing a deterrent such as bird wire, bird spikes or netting to prevent them gaining access to the area. The RSPB warn that deterrents must not kill, trap or injure birds.