Guide
K Rend cleaning: silicone render cleaning cost and care
Updated
Through-coloured render does not need painting, but it does go green. Here is what keeping it clean costs, and the one mistake that ruins the finish.
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How this calculator works
- Rates are typical 2026 UK supply-and-fit quotes: sand and cement £40–60 per m2, monocouche £45–70, silicone thin-coat £50–80. Market rates, not regulated prices: region, substrate condition and finish move them.
- House-type areas are typical net render areas (mid-terrace about 60 m2 because side walls are shared, bungalow 90, semi 110, detached 160). Measure yours for a tighter figure: wall length times height, minus large openings.
- Scaffold adds £600–£1,000, the typical 2026 cost for a two-storey house rendering job.
- Excluded: removing old or failed render (typically £20–40 per m2 on 2026 quotes), substrate repairs, and external wall insulation. Insulated render (EWI) is a different job entirely, typically £90–150 per m2 in 2026, see the render types guide.
- Re-rendering more than 50% of an individual wall's surface area counts as renovating a thermal element. Regulation 23 of the Building Regulations 2010 then requires the whole element to meet the Part L standard.
- That applies in so far as it is technically, functionally and economically feasible (guidance in Approved Document L). Budget for that conversation before stripping a solid wall.
- These are typical quote ranges, not a quotation. Renderers price on a look at the walls, always.
Why render goes green
Algae grows wherever a wall stays damp: north-facing and shaded elevations, under leaking gutters, behind vegetation. Silicone renders resist it longest because the surface sheds water.
But no system is immune: K Rend and similar coloured renders will green up in the wrong spot too. The staining is organic and sits on the surface, so it cleans off. Cleaning is a maintenance line, not a defect.
Silicone render cleaning: what it typically costs
- Soft washing (low pressure plus a biocide): typically £3–8 per m2 on 2026 quotes, so a 110 m2 semi lands roughly £330–£880, though many firms quote a flat job price with a minimum charge. Typical quotes, varies by access and how far gone the wall is.
- Biocide treatment after the wash slows regrowth, often included, worth confirming.
- Scaffold or reach equipment: most cleans are done from telescopic poles without scaffold, one reason cleaning is far cheaper than rendering.
The care rules
- Never jet wash at close range. High pressure strips the texture, opens hairline cracks and drives water into the coat. Soft wash only.
- Check the system maker's guidance before chemicals, silicone, mineral and acrylic top coats tolerate different cleaners.
- Fix the moisture source: a cleaned wall under a leaking gutter is green again in a season.
- Sand and cement is different: it is painted, so its maintenance cycle is repainting every 5–10 years rather than washing.
A note on names: K Rend is a brand (Kilwaughter Minerals), used loosely for coloured silicone renders generally, the way Hoover means vacuum. This site is not affiliated with K Rend or any manufacturer.
Weighing up a re-render because the wall looks tired? Price a clean first, then compare it with the calculator's re-render range.