Soft Washing Cardiff

What soft washing actually is

A pressure washer moves dirt by force. A soft wash kills what is growing and lets the surface release it. The pump on our soft wash gear sits between about 100 and 500 psi at the nozzle, against the 2,000 psi and upwards a rotary surface cleaner runs at on a concrete driveway. Standing in front of the fan feels like a strong garden hose.

The mix does the work. We blend a sodium hypochlorite cleaner or a quaternary ammonium biocide with a surfactant so it clings to a vertical surface instead of running straight off. It goes on elevation by elevation, bottom up, and then it sits. Nothing is scrubbed, nothing is blasted, and no water is driven into a joint, under a tile or behind a board.

Why the biocide does the work

Algae, lichen and moss are not dirt sitting on top of a wall. They anchor into it. Lichen pushes fine strands down into the pores of a concrete roof tile or a textured render, which is why scraping it off leaves a pale ghost behind and why the colour comes back the following winter. A biocide gets into the surface and kills the organism outright, so there is nothing left to grow on from.

Dwell time is what allows that to happen. Ten to twenty minutes on most surfaces, longer on heavy lichen, and on some jobs the treatment is deliberately left on rather than rinsed. That is not a corner being cut. A leave on biocide keeps working after we have packed up, and the surface carries on lightening for weeks as the dead growth weathers off in the rain.

The payoff is regrowth, or the lack of it. Jet washing a north-facing render wall takes the green off and leaves every spore sitting in the pores, so it is back within a season or two. A soft wash kills at the root, so the wall stays clean for years rather than months. That is the whole argument for treating porous vertical surfaces this way.

What grows on Cardiff walls and roofs

Rainfall does most of the damage here. Wet westerly weather off the Bristol Channel keeps render damp for days at a time, and the growth follows the water. Green algae take the shaded north-facing and east-facing elevations first. Orange or rust coloured staining on a west-facing wall is usually Trentepohlia, an orange pigmented algae that gets mistaken for rust bleeding out of a fixing. Black spotting on concrete roof tiles is lichen, and the moss on a north pitch or in a gutter almost always starts under overhanging trees in the older, leafier streets around Penylan, Lisvane and Llandaff.

Which of those you have changes the mix and the dwell, not the method. Heavy lichen on a tile roof needs longer contact and often a second look a few weeks later, once the first application has weathered. Thick moss gets brushed or scraped off dry before anything is applied, because biocide cannot reach the tile through a wet sponge of it. On a pebbledash wall the growth sits deep in the aggregate, so the mix has to be worked in and left rather than flashed over.

Which surfaces need soft washing

If a surface is porous, painted, coated or fixed with something water can get behind, it needs a soft wash. These are the ones we will not put a pressure washer near.

• Render of every type. Thin coat silicone systems such as K Rend, monocouche, pebbledash and older sand and cement all fail the same way under a lance. The thin topcoat blows off, the base coat is exposed and the water repellency goes, so the wall then wets through and stains worse than it did before.
• Roof tiles and slate. High pressure strips the granular face off concrete tiles, forces water up under the laps into the loft and breaks the mortar bedding on ridges and verges.
• Painted masonry and painted render. A lance lifts paint in strips and leaves tramlines you can read from the pavement.
• Timber, composite and metal cladding, where water pushed behind a board has nowhere to drain.
• uPVC fascias, soffits, bargeboards and downpipes, which mark and craze under a concentrated jet.
• Conservatory roofs in polycarbonate or glass, where pressure lifts the glazing bar seals and floods the frame.
• Garden walls, decorative brick and any soft lime or weathered pointing that a jet will simply wash out of the joint.

Hard, flat and unpainted still takes pressure, and we still use it. Block paving, concrete, flagstones and most patios come up faster and more evenly with a rotary surface cleaner, and tarmac gets a lower setting and a wider fan so the bitumen stays where it is. Plenty of Cardiff jobs are both. We soft wash the render, roof and uPVC, then jet wash the driveway and patio on the same visit and put kiln dried sand back into the block paving joints before we leave.

A considered soft washing process, start to finish

1. Survey and set up. We walk the property first and note what is growing, what is painted, what is cracked and where the water will run. Cars get moved, windows and doors get shut, and anything on the ground that cannot take a splash goes under cover.
2. Protect the planting. Every shrub, bed and lawn edge within reach of the spray is soaked with clean water, then sheeted where it needs to be. Wet foliage does not take up the solution. Dry foliage does.
3. Apply from the bottom up. The mix goes on the lowest part of the elevation first and works upward. Spray downward onto dry render and the runs soak in ahead of the wash, which leaves streaks that will not come out afterwards.
4. Let it dwell. Ten to twenty minutes on most walls. On heavy lichen we go over the same section a second time rather than push the strength past what the surface will take.
5. Rinse, or leave it working. uPVC, glass, painted metal and anything with a coating gets rinsed thoroughly with clean water. Most render and nearly all roofs are left treated so the biocide carries on killing after we leave.
6. Check it in daylight. We rinse down paving, planting and glass, then walk every elevation looking for missed patches and anything that has not released. Gutters and downpipes get checked for dislodged moss before we pack up.

Plants, pets, drains and run-off

At the nozzle the solution is dilute, and it is more dilute again by the time it reaches the ground after a rinse. That does not make it harmless. Neat product will bleach a lawn, mark a car and pull the colour out of block paving, so the protection at the start matters as much as the wash itself.

Most of the application is done from the ground on a telescopic lance, which keeps ladders off soft borders and off your gutter line. Pets and washing stay indoors while we spray. We stop if the wind starts carrying the fan over a boundary, and we flood the ground below the elevation with clean water before, during and after. A surface water drain sitting directly under the work gets covered or diverted. Surface water drains in Cardiff run to the Taff, the Ely and the bay rather than to a treatment works, so nothing concentrated goes down one.

What changes the price of soft washing

Prices move too much for a single figure, so here is the honest Cardiff range. A soft wash on a standard three bedroom semi usually falls between £250 and £450. A large detached house rendered on all four elevations is more often £450 to £700. Roof soft washing with moss removal included generally lands between £450 and £1,200 depending on pitch, size and access. Treat those as guidance rather than quotes.

What moves the number is height and access, how many elevations there are, how heavy the growth is, whether a conservatory or a tight side passage is in the way, and whether you want the gutters, fascias and driveway done at the same time. Bundling beats three separate visits on price every time. Quotes are free and we would rather look at the property than guess from a postcode.

How long the result lasts

On a Cardiff render wall in a normal position, two to four years is typical before another treatment is worth doing. Roofs often hold longer, four years and up, because nothing alive is left in the tile. North-facing elevations, walls under tree cover and anything shaded by the house next door come back first. A wall that sits damp all winter behind an overgrown hedge will always green up before the rest of the house, and cutting that hedge back buys you more time than another clean will.

Soft Washing expertise across Cardiff and South Wales

We cover the whole city, from the painted render on the terraces in Roath, Canton, Pontcanna and Cathays to the pebbledash semis in Whitchurch, Rhiwbina and Llanishen and the newer thin coat render and cladding out at Lisvane, Cyncoed and Radyr. Grangetown, Splott, Rumney, Llanrumney, Llandaff and Penylan are regular ground for us, and we work in Barry, Newport and across South Wales. We have been cleaning exteriors here since 2019 and hold a 5.0 rating from five Google reviews.

Call 07576 128903 or email Liamdunn2406@outlook.com to get a soft washing quote booked in. We answer Monday to Sunday, 7:00 to 21:30, and we are based in Cardiff. Tell us the surface, roughly how big it is and which way the wall faces, and we can usually give you a sensible range before we visit.