A slate roof sheds rain because each piece overlaps the courses beneath it. The exposed face can look robust, yet the edges are thin and the nails or hooks holding each slate are small. Driving a powerful jet across that surface risks lifting edges, pushing water into the laps and loosening growth in a way that carries grit across the face. Soft washing reverses the priority: the treatment does the work and the water simply rinses away what has been loosened.
Older slate roofs often have a few pieces that have slipped, cracked or been replaced with a different type over the years. Those details matter. Point them out in your photographs if you can see them from the ground, and mention any past repair work you know about. Cleaning is not a repair, so a slipped slate should be identified rather than discovered halfway through the visit.
Moss on slate usually gathers along the lower edges and in the shaded courses, where moisture lingers. Lichen forms flat crusts that grip the stone and can look unchanged straight after cleaning before it dies back with the weather. Green and black algae tint whole slopes, especially on the side facing away from the sun.
Loose moss is removed with care where it can be reached safely, then the soft wash treatment is applied. Lichen responds slowly, which is why a biocide is often discussed for slate as the separate line it always is. The lichen removal guide explains why the part you can see is only half of that growth.
Before work starts, the area below is considered. Paths, conservatories, plants and parked cars are protected or moved, and gutters and outlets are cleared after the roof clean so the loosened material does not stay at the eaves. Where a slate roof has a lead valley, a dormer or a chimney stack, those junctions are approached with the same low-pressure care.
Anything needing specialist access is discussed and priced before work starts. You will know from the quotation how the roof will be reached, which slopes are included and whether biocide is part of the scope.
Tell Jordan whether the roof is on a house, a terrace with neighbouring roofs on either side, or a commercial building. Explain whether you want appearance improved, moss stopped from reaching the gutters, or both. Send views of each slope from safe positions on the ground, and include the ground below the eaves so access can be judged.
Price depends on the roof area, pitch, height, the amount of growth and whether biocide is added. The roof cleaning cost guide explains how those factors combine. Quotes are free and written for the roof in front of us, not taken from a standard figure.
