Roof Cleaning & Surface Preparation

Yes, but technique is critical. You must use a turbo nozzle and wash down the roof (with the lap of the tile) to stop water driving up into the loft. Never aim the lance upwards.

Pressure washing only removes the visible moss. The roots remain alive in the pores. A biocide soaks in and kills these roots. If you skip this, the moss will grow back under your paint within months.

Yes. If the mortar is crumbling, power washing will blow it out completely. You should re-point any loose ridges or verges after washing but before painting to ensure a sealed, uniform finish.

Bone dry. Concrete holds water. We recommend waiting at least 24-48 hours of dry weather after cleaning before applying any coating.

This is when the factory coating peels back from the bottom edge of the sheet, exposing the steel core to rain. You must grind this loose rust back to a sound surface and spot-prime it before coating the whole roof.

This is oxidised paint resin. You cannot paint over it. You must pressure wash the roof until the water runs clear and no powder rubs off on your hand.

No. You can paint over sound rusted metal (stained but hard), but you cannot paint over flaking rust. Use a wire brush or angle grinder to remove the loose flakes first.

The rubber washers on old screws often perish. Tighten them slightly (careful not to strip the thread) and apply a dollop of "Brushable Sealer" or a focused coat of high-build roof paint over each fixing.

Absolutely not. It is illegal and dangerous. High pressure releases deadly asbestos fibres into the air. You must use a "Soft Wash" method (Biocide spray) and a hosepipe for rinsing.

Saturate the moss with a strong biocide. Leave it to die and turn brown (usually 1-2 weeks). The dead moss will naturally degrade or can be gently brushed off with a soft broom while wet.

You need to stabilise it first. After cleaning, apply a generic "Stabilising Solution" or a thinned first coat of your roof paint to bind the dusty surface together before applying the full topcoat.

Do not try to replace the sheet if you can avoid it. Clean the area chemically, then use a specialised Butyl Fleece Tape or a fibre-reinforced repair paint to bridge the crack safely.

We generally advise against painting clay tiles with a solid colour paint. The glazed surface rejects paint, leading to peeling. Instead, clean them and use a Clear Impregnating Sealer.

These "spots" dig into the slate. Pressure washing often damages the slate before it shifts the lichen. The best method is a chemical "Soft Wash" with a Sodium Hypochlorite-based cleaner, which bleaches the spot and kills the root instantly.

You risk "delamination." Slate is made of layers. High-pressure water can force these layers apart, causing the slate to flake and thin out, reducing its lifespan.

Usually, the nail has rusted through. You can use a "tingle" (a strip of lead or copper) to hook the slate back into place without needing to strip the whole roof section.