How to choose a render cleaning company: questions to ask and red flags

Updated 6 November 2026 · By the Render Cleaning team

Short answer: Choose a render cleaning company that identifies your render type, cleans at low pressure with a biocide suited to it, explains how plants and surfaces will be protected, and gives a written fixed price covering access, cleaning and rinsing. Avoid anyone who plans to pressure wash render, cannot name the products they use, or will not explain how they work safely at height.

How to choose a render cleaning company: questions to ask and red flags

Why the method matters

Render is easy to damage and hard to put right. High-pressure washing can erode silicone and monocouche finishes, leave visible stripes, dislodge pebbledash and force water into cracks. Once the surface is damaged, the only real fix may be recoating or re-rendering, which costs many times more than cleaning. So the most important question to ask is how the render will be cleaned, not just how much it costs.

The product matters as much as the pressure. Some cleaners rely on strong sodium hypochlorite, the active ingredient in bleach, which strips green colour quickly but can lighten pigmented renders unevenly, harm plants and does not always kill growth at the root. Others use quaternary ammonium based biocides that work more slowly but keep working for weeks. A good operator will explain what they use, why it suits your render and what result to expect over time, not just on the day.

Questions to ask before booking

What type of render do you think I have, and how does that change your method?
What pressure will you use on the render?
Which cleaning product or biocide will you use, and is it suitable for my render?
How will you protect plants, ponds, windows and vents?
How will you reach the upper walls, and is any access equipment included in the price?
How will you rinse so there are no patches or tide marks?
What should I expect the walls to look like straight after, and in a few weeks?
Do you recommend a protective treatment, and why?

What a good quote should include

Item	What to look for
Area	Which elevations or walls are included
Method	Low-pressure application and rinse, not pressure washing
Products	The type of biocide or cleaner to be used
Access	Ladders, towers, poles or powered access included or extra
Protection	Plants, glazing, vents and paving
Stain treatment	Rust or run-off marks, if they need separate treatment
Aftercare	Protective treatment included or optional

Without these details, two quotes cannot be compared. A much cheaper price often means pressure washing, no access equipment or no rinse.

Ask to see photos of previous render cleaning jobs on a similar render type, ideally including close-ups taken a few weeks after the clean. A wall that looks bright on the day but patchy a month later is a sign the method was wrong.

Red flags to watch for

Offering to pressure wash render or calling it a jet wash
Unable to say which product they will use
Using strong bleach on coloured render without testing
Doorstep offers to clean the walls today at a special price
No plan for working above ground floor safely
Promising the render will look brand new whatever its age or condition
Asking for full payment before any work is done

Working at height

Most render cleaning involves upper walls. Under the Work at Height Regulations 2005, anyone working at height for a business must plan the work, use suitable equipment and take steps to prevent falls. Many render cleaners use water-fed or extension poles from the ground for two-storey houses, with towers, scaffold or powered access for taller or awkward walls. Ask how the upper walls will be reached and whether that is included in the price.

Environmental care

Biocides are regulated products and should be used according to their label. A careful operator soaks and protects planting, keeps run-off out of ponds and watercourses, and avoids letting concentrated product run into surface water drains, which often lead straight to local streams. Ask how they manage run-off, especially if you have a pond or the property is next to a watercourse.

It is also reasonable to ask whether they hold the product's safety data sheet and follow it. Responsible operators wear suitable protective equipment, keep children and pets away from wet product, and avoid spraying in wind that could carry mist onto neighbours' cars, windows or gardens.

Before and after: what to agree in advance

Disputes after render cleaning usually come from different expectations rather than bad work. Agree these points before the job starts and the outcome is much easier to judge.

Point to agree	Why
Which walls are included	Avoids a clean front with a green side wall left untouched
How much of the result is immediate	Some stains fade over weeks, not hours
What will not come off	Fading, old repairs and damage are not stains
Who checks the work and when	A walk-round on completion catches missed patches
Whether a revisit is offered	Useful if lichen or deep staining is slow to fade

Take your own photos of every wall before the work starts. They are useful for comparing the result, and for showing any existing cracks or damage that were there beforehand.