K-Rend cleaning that brings colour back — without the pressure washer
K-Rend goes green, black and patchy as it ages. That is algae and lichen growing on the surface. We clean it off with soft washing, which uses low pressure and the right cleaning solution. Never a jet wash. We have cleaned render across the Midlands for over 25 years from our base in Swadlincote. You get a fixed price, before-and-after photos, and a finish that lasts.
What K-Rend is, and why it stains
K-Rend is a through-coloured render. The colour runs all the way through the coat, not just on the top. Builders use it on a lot of new homes. You will see it across the new estates in Derby, Nottingham and Leicester. It looks crisp and clean when it goes on.
But K-Rend has a slightly rough, open surface. That texture holds water and dirt. Give it a few damp Midlands winters and it starts to change colour. First it goes green. Then black. Some walls turn red or orange. Many people think the render is failing. It usually isn't. It is just covered in living growth that has fed on the damp surface.
How algae, lichen and black staining develop
The green you see is algae. The black is a tougher algae or a surface mould. The red and orange patches are another algae type. They all want the same three things: water, mild weather, and a surface to cling to. The Midlands hands them all three for most of the year.
North-facing walls stay damp and shaded, so they nearly always stain first. Walls near trees, hedges, fences or a leaky downpipe go faster too. Once the growth takes hold it spreads a little more every wet season. That is why a wall can look fine for years and then seem to turn black almost overnight.
Not sure if you have K-Rend?
It is easy to mix up. Here are the quick signs. K-Rend has an even, slightly grainy finish, a bit like fine sandpaper. The colour is the same all the way through, so a small chip shows the same shade underneath, not a grey base. It was most often fitted on homes built from about 2005 onward. If your render is smooth and painted, or has small stones pressed into it, you likely have a different type. Either way, send us a photo and we will tell you for sure. We clean every render type, and each one needs a slightly different touch.
Why pressure washing damages K-Rend
A pressure washer feels like the obvious fix. It is the worst thing you can do to K-Rend. High pressure water forces moisture deep behind the render, where it can sit and cause damp problems inside the wall.
The jet also blasts the soft, open surface and tears at it. The colour layer thins and goes blotchy. You get pale scars where the lance sat too long in one spot. That damage cannot be cleaned out or buffed away. The only real fix is to re-render the whole wall, which costs far more than the cleaning ever would.
And here is the part most people miss. Blasting only knocks the top off the growth. The roots stay alive in the surface. So it grows back fast, often within a few months. A cheap pressure wash today can lead to thousands in repairs and a wall that looks worse than before.
What K-Rend themselves say about cleaning
K-Rend describe their render as a low-maintenance finish that benefits from a gentle clean every few years, to lift off algae, bird mess and the film that weather leaves behind. For algae, they recommend treating it with a biocide — which is exactly what soft washing does. They also warn that high-power pressure washers can damage the render surface.
We take that a step further and skip the pressure washer completely. You can read K-Rend's full maintenance guidance on their own website. If a quote sounds cheap because someone plans to "blast it clean", treat that as your warning sign.
That is just one thing worth checking before you let anyone near your render. If you are gathering quotes, it pays to know what to ask before you hire a render cleaner — so whoever turns up treats K-Rend the way it should be treated.
Our K-Rend cleaning method
We use soft washing. That means low pressure plus the correct cleaning solution that kills the staining at the root. The solution does the work, not brute force. Here is exactly how a job runs, start to finish. You can read more on our full render cleaning process page.
Porosity assessment
We test how much water your render soaks up. Soft, thirsty render needs a gentler mix and a different dwell time. Reading a wall correctly is where 25 years on the tools earns its keep.
Soft wash application
We apply a biocide at the correct strength. A biocide is a cleaning solution that kills algae, lichen and mould. We spread it gently and evenly across the whole wall at low pressure.
Dwell time
We let the solution sit and do its job. This is the quiet step the cowboys skip because they are in a rush. Skipping it is why blasted walls grow back so fast.
Controlled low-pressure rinse
We rinse with low pressure water — think a strong garden hose, not a jet wash. The dead growth and dirt lift away cleanly, and the surface stays unharmed.
Aftercare guidance
We show you simple ways to keep the wall cleaner for longer. The biocide also keeps killing new spores for months after we leave, so the clean finish lasts far longer than a quick blast ever would.
Got more than one type of render on your property? Many Midlands homes mix K-Rend with other coats. Take a look at our monocouche render cleaning as well — we handle both on the same visit.
Meet Stephen Fudge
"I clean every wall myself. No subcontractors, no rushed crews. Just me, the right method, and 25 years of knowing how render behaves."
I started in exterior cleaning back in 2000. Before that I worked as a Local Authority Cleaning Inspector, so checking that a job was done to a proper standard was literally my job. That habit never left me. When I clean your K-Rend, I treat the wall the way the manufacturer says it should be treated, not the quick way.
In that time I have seen what a pressure washer does to soft render, and I have cleaned the same walls properly afterwards. That is why I will never blast your home. Here is what you get with me:
- Every job done by me, the owner — never passed to a subcontractor
- 25+ years of hands-on exterior cleaning across the Midlands
- Former Local Authority Cleaning Inspector
- Before-and-after photos taken on every single job
- £1 million public liability insurance, for your peace of mind
- An honest fixed price, given to you up front
Stephen FudgeFounder & lead operator, Midland Render Care · Read more about Stephen
Homeowners rate us 5.0
Every review below is a verified Google review from a real customer — for cleaning render the right way, without the damage.
"Fantastic work and great service, came out to check the chemical had worked, which it had. Great to deal with Stephen and I look forward to using him in the future."
"We had Midland Render Care come out and soft wash our house. Stephen did a great job — the house looked really good afterwards. I would highly recommend this company."
"I would have no hesitation in recommending Stephen to clean rendering. He is both professional and competent in his work, and up front and free with advice and information."
Signs your K-Rend needs cleaning
Not sure whether your render is just weathered or genuinely growing algae? After 25 years on Midlands render, these are the three signs worth acting on. Spot any of them and it is worth a free assessment — send a photo and we will tell you exactly what we are looking at.
Green, black or red patches
A green film, black blotches or rusty-red patches spreading across the render are all living growth — algae, lichen or surface mould feeding on the damp surface. It is not the render failing, but left alone it spreads a little further every wet season.
One side darker than the rest
If a single elevation looks far worse than the others, it is almost always the north-facing or shaded one. It stays damp longest, so growth takes hold there first — a clear sign the wall is holding moisture rather than drying between showers.
Streaks below gutters or fittings
Dark runs or rusty streaks below a gutter, satellite dish or light fitting usually point to a fault feeding the staining — an overflowing gutter or a non-stainless bracket. We clean it off and flag the cause so it does not just come straight back.
How much does K-Rend cleaning cost?
We quote a fixed price up front. No hourly rates, no surprises on the day. The price depends on the size of the property, how easy the walls are to reach, how bad the staining is, and the render type. As a rough guide:
You get the full figure after a free assessment, with nothing hidden. For a full breakdown of what changes the price, see our render cleaning prices page.
Areas we cover for K-Rend cleaning
We work within about 45 miles of our Swadlincote base (DE11). Derby has a high number of K-Rend homes in Allestree, Mickleover and Littleover from the building boom. Nottingham's K-Rend sits mostly in West Bridgford, Wollaton and Mapperley. We cover these towns and the villages around them:
The best time to clean K-Rend in the Midlands
The honest answer is that soft washing works in almost any season. The cleaning solution does the job, so we are not waiting on hot sun the way a pressure wash crew might be. That said, a few Midlands patterns are worth knowing.
Spring and early autumn are the sweet spots. The walls dry between showers, and you head into the next damp spell with a clean, treated surface. Many homeowners book in late summer so the render looks its best before the dark winter months.
Winter cleaning is fine too, as long as it is not freezing. In fact, that is when staining looks at its worst, so it is often when people first notice the problem. We work through the colder months across Derby, Burton and the surrounding villages. The one thing we avoid is treating a wall during a hard frost, since the solution needs liquid water to work and dwell properly. If the forecast turns, we simply rebook you. No fuss.
K-Rend cleaning, answered
Can K-Rend be cleaned without damaging it?
Yes. K-Rend cleans up very well with soft washing. The trick is low pressure plus the right cleaning solution, given time to work. Done this way, the render is left unharmed and the colour comes back. The only way to damage it is to jet wash it.
Will the green and black come back?
It comes back far more slowly after a proper soft wash, because we kill the growth at the root rather than just knocking the top off. The biocide keeps working for months. Most homes stay clean for a few years. North-facing walls and shaded walls may need a touch-up sooner.
How long does a K-Rend clean take?
Most homes are done in a day. A large detached house with tricky access can take a little longer. We give you a clear time when we quote, so you know what to expect.
How do you protect my plants and pets?
With method, not promises. We pre-wet the plants around the walls before we start, apply the solution at the correct strength rather than mixing it strong, and rinse everything down afterwards. We will ask you to keep pets indoors while we work and until the surfaces are dry.
Why is my K-Rend black on one side only?
Almost always it is the north-facing or shaded side. It stays damp longest, so algae grows there first and thickest. Walls near trees, hedges or a dripping gutter go the same way. We treat the whole property so it ages evenly.
Why is there a rusty or dark stain running down my render?
Often it is coming from a bracket above it — a satellite dish, an outside light, or a hanging-basket hook. K-Rend point out that cheaper, non-stainless brackets can rust or lose their paint, and that runs down and stains the render. We can clean the stain off, and we will flag the cause so you can swap the fitting for a stainless one to stop it coming back.
Can you clean K-Rend without ladders?
Yes. Soft washing is done from the ground using low-pressure equipment that reaches the full height of most homes. That keeps the job safe and means no ladders leaning against your fresh render.
How often should K-Rend be cleaned?
For most Midlands homes, every three to five years keeps it looking right. Shaded or north-facing walls may want it a little sooner. We will give you an honest view at the assessment rather than book you in too often.
More questions? Read our full render cleaning FAQs, or see the questions worth putting to any cleaner before you hire — how to choose a render cleaner.
Not ready for a quote? Take the free guide
Stephen's plain-English guide to looking after render, drawn from 25 years on the tools. No jargon, no hard sell — just what helps your render and what harms it.
- Why render goes green, black and red — and what it really is
- The one mistake that ruins render, and how to dodge it
- A simple checklist to keep your walls clean for years
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Request a free K-Rend assessment
Send us a couple of photos of your render and we will tell you the staining type, flag any problems, and give you an honest fixed price — usually within 24 hours. Prefer to talk? Call Stephen on 01283 293283.