Soft Wash Roof Cleaning questions answered in plain English

A 3-bed semi-detached roof typically costs €300 to €1,800, a 4-bed semi €900 to €2,300, a bungalow €600 to €1,800, and a detached house €450 to €3,000+. Prices include the reduced 13.5% VAT rate.

Soft washing cleans a roof at low pressure (similar to a garden hose) using a biodegradable surfactant and either a sodium hypochlorite wash or a slow-acting residual biocide (DDAC/BAC), after any heavy moss cushions are scraped off by hand.

Yes. High-pressure jet washing strips the factory protective granule layer off interlocking concrete tiles, making them porous so moss regrows faster, and can force water up under the tile laps onto the sarking felt.

Yes, when cleaned from a scaffold tower, cherry picker or ridge-hooked roof ladder without walking directly on the slates. Older fibre-cement slates must never be hit with high pressure as they can delaminate.

A manual moss scrape followed by a soft wash or residual biocide treatment typically keeps an Irish roof clear of heavy moss for 3 to 5 years, depending on local rainfall and overhanging trees.

Yes — scraping and soft washing a roof always involves bagging or plugging the downpipes and clearing all dislodged moss from the gutters afterwards (€80 to €200 when booked on their own).

Yes, provided the crew keeps sodium hypochlorite away from anodised aluminium solar frames and EPDM skylight seals, using pH-neutral biocide and de-ionised water rinsing around the panels.

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Walking directly on concrete tiles or slates cracks brittle noses and hip tiles, while firing a 3,000 PSI pressure-washer lance down or across the roof strips the protective surface of concrete tiles, tears aged sarking felt and drives dirty water over the headlap into your attic insulation.

A sodium hypochlorite soft wash sanitises the roof and lifts black algae and yellow lichen spots on the day of cleaning so you see an immediate colour transformation. A DDAC/BAC residual biocide treatment after manual moss scraping leaves no bleach smell, is gentler on surrounding gardens, and lets natural rainfall wash dead lichen and algae away gradually over 3 to 6 months.

A careful soft wash crew bags or bungs every rainwater downpipe before spraying, pre-wets all surrounding flowerbeds and grass with clean water, sheets delicate shrubs or ponds, and rinses and neutralises any overspray immediately. Pets are simply kept indoors until the roof and patio are rinsed dry.

Yes, provided the downpipes are disconnected and diverted before a single drop of cleaner is sprayed. Never allow roof biocide or sodium hypochlorite runoff to enter a rainwater harvesting cistern or a biological septic tank.

Once heavy moss is scraped off and the porous tile surface is sanitised deep in the micro-pores, a roof typically stays clean for 3 to 5 years. A light 1-hour top-up biocide spray from the ground or gutter line every 3 years keeps moss from ever re-establishing.

Yes — red, green and black algae streaks on K-Rend, monocouche and painted sand-and-cement walls are caused by the exact same airborne spores as roof algae. Soft washing the walls alongside the roof and gutters saves a separate access set-up and stops roof spores washing back onto clean walls.