Softwashing and pressure washing are often talked about as rivals, as though one is modern and the other crude. They are simply two tools that suit different materials. Pressure washing removes what is sitting on a surface by force. Softwashing kills what is growing into a surface with a treatment and lets it weather off. Use the wrong one and you get either a wall with lance marks striped across it, or a driveway that still has moss in every joint. This guide runs through the surfaces we are asked about most often around Plymouth and says plainly which method belongs on each and why.
Rendered and painted walls: softwash
Render is a thin decorative coat over a substrate, and pressure drives water behind it as well as removing the finish. Thin-coat silicone systems mark permanently under a lance, and older sand and cement render is usually crazed enough that forcing water in is a genuinely bad idea. Softwashing puts a biocidal treatment onto the surface at garden-hose pressure, kills the algae and lichen at root level, and the wall lightens over the following days and weeks as the dead growth washes off in rain.
This guide sits under our Wall Cleaning & Softwash work, covering 20-mile radius of Plymouth.
Roof tiles: softwash, almost always
Concrete and clay tiles are porous and their surface layer is what keeps them shedding water. Pressure washing a roof strips that layer, blasts out ridge and verge mortar, and forces water under the laps into the loft. It also looks dramatic and instant, which is exactly why it still gets sold. Softwashing a roof is slower to show results but leaves the tile intact, and the moss dies rather than being knocked off to regrow from the roots left behind.
Concrete, block paving and tarmac: pressure
Hard, thick, non-decorative surfaces are where pressure washing earns its place. Block paving in particular needs mechanical energy to lift compacted silt and moss out of the joints, and a rotary surface cleaner gives an even finish without the striping you get from freehand lance work. The one caveat is joint sand: pressure removes it and it must be replaced afterwards, which is part of the job rather than an upsell.
Natural stone paving: it depends on the stone
Indian sandstone and limestone are softer than they look and will pit and lighten unevenly under a close lance. They are usually cleaned with moderate pressure at a sensible distance, often after a treatment has already killed the black spot lichen that pressure alone will not shift. Porcelain and granite tolerate more. Slate riven surfaces can delaminate if attacked. The rule is to test in a corner and work up, never to start at full power.
Timber decking and fencing: gentle, or softwash
Wood fibres tear under pressure, which is why badly washed decking goes furry and then greys again within a season. Low pressure with the grain, or a treatment approach, keeps the surface intact. Fences are usually best treated rather than blasted, particularly featheredge and closeboard panels that will not survive the experience.
uPVC, cladding and conservatory roofs: softwash
Plastics scratch, and scratched uPVC holds dirt worse afterwards, so each clean gets harder. Fascias, soffits, cladding and conservatory roof panels are washed with a soft brush and a suitable detergent, usually on a water-fed pole, with pure water as the final rinse so nothing dries on. Pressure near a conservatory roof also risks pushing water past seals and glazing bars.
Brick and stone walls: mostly softwash
Old brick and rubble stone are held together with mortar that is often lime, soft, and much weaker than the units around it. Pressure strips pointing quickly and expensively. Growth on masonry is a biological problem and responds to a biological solution. Efflorescence, on the other hand, is a salt bloom and is brushed off dry rather than washed at all.
What good practice looks like on the day
In reality most houses need both methods in one visit: softwash for the walls, roof, soffits and conservatory, pressure for the drive and paths. What matters is that the operator changes method between them rather than reaching for the same lance all day. If someone proposes to pressure wash your render or your roof tiles, that is the point to stop and ask a few questions.
Questions we get on this
- Is softwashing slower to show results?
- On roofs and heavy lichen, yes. Walls usually lighten noticeably within days, but full die-back on a roof continues over weeks as rain washes the dead growth away.
- Can pressure washing damage render permanently?
- It can. Thin-coat systems mark where the lance dwelt, and water forced behind render or under tiles causes problems that cost far more than the clean.
- Why does my drive need pressure but my wall does not?
- Concrete and block paving are thick, non-decorative and hold dirt mechanically in joints. Render is a thin finish where growth is biological and rooted.
- Do you use both methods on one visit?
- Usually. Walls and roof are softwashed, hard landscaping is pressure washed, and each surface gets the method that suits it.
Related reading
- Solar panels, roof access and cleaning around them
- Flat roofs, valleys and where water actually goes wrong
- Chimneys, ridges and the growth nobody can see
- Victorian terraces: cleaning a house with no side access