This is a render cleaning before and after write-up on a job we did last month, a two-storey semi on the edge of Sowerby, just outside Thirsk. The owner had been looking at the front of the house for three years thinking it would be fine after a good summer. It wasn’t.
Houses don’t tend to clean themselves. This is what the job actually looked like, from the first phone call to the final invoice.
What the render cleaning before and after walk-up looked like
The property is a 1990s semi-detached with K-rend silicone render across the front and gables. Cream colour, originally. By the time we arrived, the cream was a memory.
The front face had a uniform green tinge across the lower two-thirds, deepest under the kitchen window where the overflow from the boiler drips. The north gable was a different story: black streaks running from the top corner down to the damp-proof course, classic Trentepohlia algae feeding on the constant shade and the runoff from a poorly-pointed coping stone.
The owner had tried hosing it down the previous summer. The hose moved the surface dirt around but did nothing to the staining. She had also priced up a render redecoration job and been quoted around £4,800.
A clean was going to cost a fraction of that.
The site visit
A 20-minute site visit, mostly for me to look at three things.
Surface condition. No cracks deeper than a hairline. Render fully intact. Good candidate for a clean rather than a strip-and-recoat. We confirmed it was silicone-based K-rend by feel and by the manufacturer’s plate at the side of the property.
Aspect and shade. The north gable was the worst affected, as expected. The front face was lighter on the south end and heavier on the north end, in proportion to the daily sun hours.
Access. Standard. Van could park on the street, hose reach to the back garden, no scaffolding needed for a two-storey job because the soft wash gear has the reach for it.
I quoted £420 for a full wraparound clean (front, both gables, back) including the boiler-overflow streak and the run-off from the bay window. Booked her in for the following Tuesday.
The work, in order
Day one, mid-morning to mid-afternoon.
- Pre-rinse of the worst-stained areas to wet the surface and prepare it for the chemistry.
- Biocide application at 1:5 dilution on the heaviest streaks, 1:8 on the lighter areas. Applied via low-pressure spray, working systematically across each face.
- Dwell time of around 45 minutes while the chemistry breaks down the algae cell walls. We use this time to do the back wall and far gable.
- Soft wash rinse at very low pressure, taking the dead growth off the render surface. The visible black and green came off in sheets in some places, in a slow grey wash in others.
- Final rinse of the windows, the surrounding driveway, and the patio paving where the runoff had spread.
Total time on site: just under five hours.
The before and after
Photos tell most of this. The front face went from a uniform mid-green to its original cream. The north gable went from blackstreaked to a clean, even render. The boiler-overflow stripe under the kitchen window came off entirely.
The owner came out before I left and said the thing every render cleaning before and after job ends with: “I’d been putting that off for two years and I have no idea why.”
What it costs and what it lasts
The full job came in on the quote, £420 including all four faces and the surrounding rinse.
A soft wash render clean of this kind lasts three to five years on a sheltered front, two to three years on a heavily shaded north face under trees. We’d expect to see this property again in 2029 or 2030.
The full render cleaning service page walks through the chemistry and the process if you want the longer technical version. We cover Thirsk, Sowerby, and the surrounding villages