Render is one of the hardest things on a house to price from a phone call. Two walls the same size can need very different amounts of work, and a price given without seeing the wall is either padded to cover the worst case or quietly revised on the day. This guide sets out what Whales charges for render cleaning, what actually moves the figure, and how to get a fixed price for your own walls without anyone visiting first.
The starting rate
Render cleaning starts from £6/m². That rate covers a full soft wash: the treatment goes on at low pressure, is left to kill the green algae and lift the grey atmospheric staining, and is rinsed gently. The biocide is included, not an add-on, because a wall that is only rinsed goes green again quickly. There is no pressure washing at any stage, which is the point. Render is a thin coating, and force is what marks it, drives water in behind it and takes pieces off the wall.
The rate is charged on the area of render actually being cleaned, not the footprint of the house. A detached house with render on every elevation and a terrace with one rendered front are measured very differently, and windows, doors and brick sections are not part of the area. That is why a rate per square metre is more honest than a flat price per house, and also why a quote needs photos.
What moves the price
1. How much of the house is rendered, and which walls
Plenty of enquiries are for one wall rather than the whole house. It is usually the north-facing elevation, which gets little direct sun, stays damp longest and goes green first for the same reason the north pitch of a roof does. Our guide on why north-facing roofs go green first explains the pattern. Cleaning only the wall that needs it is a smaller job and a smaller bill, and James will say so if the other walls can wait.
2. Height and access
A ground-floor extension is a different job from a three-storey gable end. Height, a conservatory or flat roof in the way, a narrow side passage, or a wall that backs straight onto a neighbour's garden all change how the wall is reached and how long it takes.
3. The type of render
Whales cleans K-Rend, monocouche, pebbledash, traditional and painted render. The method is a soft wash on all of them, but they do not behave the same. Textured and pebbledash finishes hold more growth in the surface and take longer to treat and rinse evenly than a smooth through-coloured render. Older render that is already soft or crumbly at the surface needs a gentler, slower approach again. James checks the finish from the photos before pricing it.
4. How far it has gone
A light green tinge along the bottom of a wall is a quicker job than render that has gone dark and streaky from top to bottom after years without attention. Heavy, established growth needs longer dwell time and sometimes a second application before it rinses clean. Leaving a wall another year or two rarely saves money. It usually means the same wall costs more to put right.
5. What sits next to the render
Render rarely goes green on its own. The fascias and soffits above it, and the gutter that overflows onto it, are often part of the reason it is stained. Adding a gutter clearance, from £85, or a fascia and soffit treatment to the same visit is usually better value than booking them separately, and it stops the wall being stained again by the run-off from a blocked gutter straight after it has been cleaned. Our guide to fascia and soffit cleaning covers how that part of the job is done.
What is not in the price
Cleaning is not repair. If the render is cracked, blown or coming away from the wall, the soft wash will not fix it, and James will say so from the photos rather than after the job. Cleaning can make an existing crack easier to see, because the staining that was hiding it has gone. It is also not painting. Painted render that has faded or flaked will come back clean, but it will not come back a new colour.
Why a cheap pressure-washed quote can cost more
The lowest quote for a rendered wall is often a pressure wash, because it is quicker on the day. The wall looks clean when the van leaves. The trouble shows up later: marks in the finish, water pushed in behind thin render, patches blown off around the edges, and growth back within months because nothing killed it at the root. Repairing render costs far more than cleaning it. If a quote for render mentions a pressure washer, ask what it is for. Our guide on soft washing vs pressure washing sets out which surfaces can take pressure and which cannot.
Weather and timing
Soft washing depends on the treatment being given time to work, so it needs suitable weather. Heavy rain straight after application washes it off before it has done its job, which is why a render clean may be moved if the forecast turns. It does not change the price. It is the reason the price can be fixed in the first place, because the job is only done in conditions where it will work.
How to get a fixed price
Send James two or three photos: one of each wall you want cleaned, taken from far enough back to show the full height, and one close-up of the worst patch. Mention roughly how high the house is and anything in the way, such as a conservatory or a narrow side passage. He will tell you which walls need doing, whether the gutters or fascias above them are part of the problem, and what it costs before anything is booked.
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