House render & wall cleaning Bristol & Bath

Last updated: 2026-05-21 · Founder-led · £5m insured · 7-day rework

Monocouche, sand-and-cement, pebbledash, Tyrolean, painted masonry, K-Rend, silicone render, Pennant sandstone and Bath stone. Soft-wash chemistry, never high-pressure jets. Method matched to the substrate. The original finish comes back without harming the wall. Free quote on 07763 741067.

Can pressure washing damage render?

Yes, easily. Pressure washing K-Rend, silicone or pebbledash strips the top coat off and you'll see ghosting within six months. We saw a house in Westbury Park last autumn where the previous lot had gone in heavy and the gable came up patchy by spring. Use soft washing instead. Low pressure, the right mix of sodium hypochlorite, and the render stays put.

Tired of black streaks, green algae and tide marks on the render?

The west-facing wind off the Severn carries moisture all year. The north elevation rarely sees direct sun. The gutter overflowed in last winter's storm and left a dark tide mark running down the render below. Three or four years on from a fresh render or repaint, the same pattern shows up across Bristol and Bath. Organic green growth. Sooty black streaks below copings and window heads. Peeling paint where moisture has been trapped. A tired, mottled look that drags down the entire elevation.

We clean render properly. Soft-wash chemistry, never high-pressure jets. Owner-operator, Bristol-based, working across the BS and BA postcodes. The original finish comes back without harming the substrate. Most of the time the render does not need a recoat. It needs the right chemistry at the right dilution and a gentle rinse.

We used to sell residual top-up biocide as a default add-on. Stopped after enough customers told us they were happy with the bare clean and felt pressured by extras. Now it is offered, never assumed. Five-minute conversation on the day. You decide.

Render types we clean

We work across every common render system you'll see on residential properties in the BS and BA postcodes. The chemistry, dilution and dwell are matched to the substrate. There is no "one product fits all" approach.

Monocouche (one-coat, through-coloured)

Single-coat mineral render where the colour is dispersed throughout the body. Weber, Parex, Sto. Aggressive cleaning literally removes the coloured top layer and exposes a pale, patchy substrate underneath. We use a low-strength biocide application with extended dwell. Rinse pressure stays below 350 PSI (roughly the pressure of a domestic garden tap), through a fan tip held well off the wall.

Sand-and-cement (smooth, pebbledash, Tyrolean)

Older Bristol and Bath properties (1930s to 1970s semis and bungalows in Bishopston, Brislington, Twerton, Oldfield Park) typically carry sand-and-cement. The cement-rich surface is alkaline and porous, exactly the environment algae and lichen love. Sodium hypochlorite at controlled dilution with a surfactant for dwell on textured surfaces. Pebbledash and Tyrolean want longer biocide contact because the irregular surface holds growth deep in the texture.

K-Rend, silicone & through-coloured

Manufacturer-warranted estate render on newer Bristol and Bath developments. K-Rend, Weber, Parex all publish maintenance guidance that explicitly prohibits high-pressure cleaning. K-Rend's published guidance recommends low-pressure rinsing and biocide treatment only. We work to manufacturer-compliant dilutions and document the protocol so your warranty stays intact.

Painted masonry & painted render

The gentlest approach we have. Too strong a chemical concentration can leach pigment. Too high a rinse pressure can lift any paint that has already begun to fail. We always do a discreet test patch on a south-facing or hidden elevation before treating the full property. Where paint is already failing, we tell you honestly that cleaning will speed up the inevitable repaint.

Pebbledash & Tyrolean texture

The irregular surface holds biological growth deep in the texture. Surfacted biocide with extended dwell so the chemistry penetrates the voids. Rushing the rinse just pushes contamination further in. Common across 1950s and 1960s semis in Knowle, Brislington and Hartcliffe. A two-pass clean is standard on north elevations under tree cover.

Stone walls (Pennant, Bath stone, limestone)

Bristol's Pennant sandstone and Bath's oolitic limestone are porous, soft, and historically significant. Pennant tolerates moderate biocide chemistry well. Bath stone does not. We use a near-neutral, conservation-grade biocide at very low concentration with extended dwell. Two visits may be needed for heavily soiled elevations rather than risk the stone itself. We do not use sodium hydroxide on natural stone, ever.

Why we never use high pressure on render

This is the single most important section on this page if you are about to instruct a render cleaner. High-pressure jet washing (anything above roughly 1,000 PSI held close to the wall) is the wrong tool for render. Here is what it does.

• It opens hairline cracks. Render naturally develops fine surface cracking around openings and at panel junctions. Pressurised water forces moisture deep into those cracks, where freeze-thaw cycles widen them through the following winter.
• It blows the surface. On monocouche and lime-based finishes, the float coat is the working surface. Pressure washing scours that layer off and leaves a paler, rougher, irregular finish that no amount of rinsing will repair.
• It drives water behind the render. Where the render meets windows, cills, copings or DPC junctions, jet pressure forces water into the wall build-up. Internal damp follows. On insulated render systems, the insulation board itself saturates.
• It voids the manufacturer warranty. K-Rend, Weber and Parex all publish maintenance guidance that prohibits high-pressure cleaning. Use a jet wash and your render warranty is gone, and so, often, is the render.

Soft-wash chemistry does the work. Water at low pressure simply removes the residue. That is the correct method, and it is the only method we use on render.

How we pick the method

Substrate, paint condition, biological load, height, and the temperature on the day. Five variables, one decision per elevation.

Standard NaOCl soft-wash (sand-and-cement, pebbledash)

Sodium hypochlorite at the right available-chlorine percentage, blended with a non-ionic surfactant for dwell. Applied bottom-up to prevent streaking. Twenty to forty-five minute dwell. Low-pressure rinse through a wide fan tip held at distance.

Manufacturer-compliant dilution (K-Rend, monocouche)

Lower concentration, manufacturer-spec dwell, no rinse pressure above 350 PSI. We document the dilution and dwell so your warranty position stays intact. Two-pass clean on heavily-loaded north elevations.

Heritage protocol (Bath stone, limestone, listed)

Near-neutral conservation-grade biocide at the lowest viable concentration. Extended dwell. Gentlest possible rinse. Two visits if needed rather than one heavy pass that opens the calcareous surface up. We work with conservation officers where listed buildings are involved.

Optional residual top-up (any substrate)

Final fine-mist application of a residual biocide, no rinse, that extends the clean-look life by 12 to 24 months. Offered as an extra. Never included without your agreement.

How a render clean actually runs

1. Pre-inspection. Walk the elevation looking for loose render, paint defects, failed mastic at window junctions, missing or damaged copings, signs of structural movement. If we find loose render that could fall when wet, we stop and recommend a renderer first.
2. Plant, PV and surface protection. Every plant within the splash zone is wetted with clean water then sheeted where practical. Solar PV arrays masked at the lower edge. Door seals, vents and open windows checked. Cars moved or covered. Pond inlets isolated.
3. Soft-wash biocide application with dwell. Low pressure through a soft-wash pump. Bottom-up first pass to prevent streaking, top-down second pass. Manufacturer-spec dwell time. This is where the cleaning actually happens.
4. Low-pressure rinse. Clean water at low pressure through a wide fan tip held at distance. Takes off dissolved biofilm and spent biocide. On heavily contaminated walls a second pass may be needed.
5. Optional residual top-up. Fine-mist application, no rinse, for long-term protection. Offered, never assumed.
6. Walk-round and photos. Sign-off in daylight. Photos by email or WhatsApp same day.

What drives the cost

There are no fabricated quick-quote figures on this page because every property is genuinely different. The honest variables are these.

• Elevation area in square metres. A typical detached three-bed semi in Bristol carries 80 to 140 m² of renderable wall area. A four-bed detached, 150 to 220 m². We measure from your elevations or, where drawings aren't available, from a site visit.
• Height and access. Single-storey rear extensions are quick. Two-storey gables reachable from a long pole are standard. Three-storey townhouses in Clifton, gable-end terraces with no rear access, and properties needing a cherry-picker or scaffold tower carry an access premium that we cost transparently.
• Biological load. A wall cleaned within the last three years takes one biocide pass. A wall not cleaned in fifteen years and facing north onto a wooded plot may need two passes and a return visit.
• Substrate sensitivity. Bath stone and listed-building elevations take longer per square metre because the chemistry has to be gentler and the dwell time longer.
• Optional residual biocide. Quoted as a per-square-metre add-on. Most customers go without.

Indicative range for 2026: a soft-wash on a standard semi-detached render runs £450 to £750. Larger detached homes in BS9 or BA1 typically run £750 to £1,400. Bath stone elevations sit higher because the heritage protocol takes longer per square metre. See the guarantee page for the full logic.

Honest hedge. Most of the time those ranges hold. Multi-storey townhouses, scaffold-required jobs and listed buildings sit higher because the access and the chemistry both take longer.

Where we work

The damp, mild, prevailing-westerly climate of the Bristol Channel coast produces some of the heaviest algal loads in southern England. North-facing walls (particularly in tree-shaded gardens in Henleaze, Westbury Park, Sneyd Park, Combe Down and Lansdown) develop dense organic growth within three to five years of a clean. South-facing walls, by contrast, may go a decade.

10 cities and towns we cover

• Bristol
• Bath
• Keynsham
• Saltford
• Portishead
• Clevedon
• Thornbury
• Nailsea
• Yate
• Chew Valley

Sub-areas and neighbourhoods we work in regularly

• Clifton
• Redland
• Cotham
• Bishopston
• Henleaze
• Westbury-on-Trym
• Stoke Bishop
• Sneyd Park
• Lansdown
• Bathwick
• Widcombe
• Combe Down

Bath's Georgian and Victorian limestone terraces in Bathwick, Widcombe and the lower reaches of Lansdown Road want the gentlest chemistry we carry. The city's UNESCO World Heritage status and the conservation-area controls across most of the historic core mean no aggressive cleaning method is appropriate. Conservation-area restrictions across Clifton, Cotham, Redland, central Bath, Cleeve and parts of Long Ashton require methods that produce no airborne mist and no overspray. Soft-wash at low pressure, applied through a non-atomising tip, meets those requirements. See areas we cover for the full list.

Recent render work

BS9, Henleaze. K-Rend semi, north gable, October 2025.

K-Rend silicone topcoat, four years down, north-facing gable under a mature beech. Heavy algal sheeting, light lichen at the cill line. Manufacturer-compliant dilution, two-pass soft-wash, optional residual top-up declined. Customer's neighbour booked the same job after seeing the result. Photo handover the same evening.

BA1, Lansdown. Bath stone front elevation, March 2026.

Grade II listed Georgian terrace. Bath stone with biological soiling and light gypsum crust. Heritage protocol, lowest viable concentration, two visits a fortnight apart rather than one heavy pass. Conservation officer signed off the method statement. Slow visible result, finished cleanly without opening the calcareous surface.

BS6, Westbury Park. Pebbledash semi, north and east elevations, February 2026.

1960s pebbledash, never cleaned. Heavy algal load, tide mark below an overflowing gutter from the previous winter. Gutter cleared first, render soft-washed three weeks later once the substrate had dried.

Frequently asked questions

How often should I clean my render?

For most Bristol and Bath properties, once every four to six years is right. North elevations and shaded plots may want a 3-year cycle. Sun-exposed south walls can stretch to 8 or 10. A residual biocide top-up extends the interval.

Will the cleaning damage my paint?

On sound paintwork, no. On paint that is already failing (flaking, blistering, or chalking heavily) soft-wash cleaning will speed up the loss of any paint that was about to fall off anyway. We always test a discreet patch first and tell you honestly what we expect.

Will it kill my climbing plants?

Wisteria, ivy, climbing roses and similar should be cut back or shielded before cleaning. We wet down and sheet plants within the splash zone, but we cannot guarantee a climber that is in direct contact with a wall being treated. We discuss options at the quote stage.

Will it remove the green colour completely?

Yes. The biocide kills the algae and lichen that produce the green and black colouration. The colour fade keeps going for one to four weeks after we leave as the dead organisms break down and weather away. The wall looks better the day we leave, and noticeably better still a month later.

Can you clean just one elevation?

Yes. Many of our jobs are single-elevation north walls where the rest of the property is fine. Single elevations are quoted on the same per-square-metre basis as full properties, with a small minimum-visit charge to cover travel and setup.

Related services

Render cleans pair well with a roof clean, gutter clear and driveway wash on the same visit because the access kit is already on site.

• Driveway & patio cleaning
• Roof cleaning
• Soft washing
• Gutter, fascia & soffit cleaning
• K-Rend & silicone render cleaning
• Hot washing
• Conservatory cleaning
• Window cleaning
• Solar panel cleaning
• Commercial exterior cleaning

Get a render quote

Send a few phone photos of the elevation you want cleaning. Three or four shots showing the whole wall, plus one close-up of the worst patch. We come back inside 24 hours. Quotes are free, on-site where needed, and itemised.

Phone: 07763 741067. WhatsApp: +44 7763 741067. Email: enquiries@bristolandbathexteriorsolutions.co.uk. Send photos for a quote via the quote form.