What is silicone render?
By Eli Gjoka · Updated
Short answer
Silicone render is a thin, through-coloured finish for outside walls, bound with silicone resin so rain beads off while moisture inside the wall can still escape. It goes on at a few millimetres thick over a prepared base coat and primer, comes in a wide range of colours and doesn't need painting. Most houses can be rendered without planning permission if the finish looks similar to the existing walls, but conservation areas and listed buildings need permission first.
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How silicone render works
The silicone in the top coat makes the surface water-repellent, so rain runs off instead of soaking in. At the same time it stays vapour permeable, which means moisture inside the wall can still get out. Weber describes its webersil TF finish as silicone-based, through-coloured, highly vapour permeable and UV stable, and it comes in more than 100 colours.
Because the colour runs all the way through, small knocks don't show a different colour underneath, and the walls don't need painting to look finished.
What goes on the wall
Silicone render isn't a single coat. It's a system, and the build-up depends on what the wall is made of. On masonry, Weber's silicone system is:
- a preparation coat where the wall needs it
- a base coat
- a primer, tinted to suit the top coat
- the silicone top coat, about 1.5mm thick
On render boards or external wall insulation, a reinforcing mesh is bedded into the base coat. Not every system uses mesh, so the right build-up is chosen for your walls at the survey, not from a standard list.
Silicone render or monocouche?
Monocouche is a cement-based, through-coloured render applied in two passes as one thick coat, around 15 to 18mm, and usually given a scraped finish. Silicone render is a thin coat of a few millimetres over a base coat.
- Finish: silicone gives a fine, even texture; monocouche usually has a scraped look.
- Water: silicone is water-repellent at the surface; monocouche relies on its thickness.
- Insulation: thin-coat systems like silicone are the ones used over external insulation boards.
- Weather: both have similar application limits, at least for the Weber products.
We specialise in silicone render with Weber products and don't apply monocouche, so if you're comparing quotes, ask exactly which system each one includes.
Is it really self-cleaning?
You'll often see silicone render described as self-cleaning. Weber's own wording is more careful: “low susceptibility to soiling”. It stays cleaner than many finishes, but it still benefits from a wash. Weber suggests washing render once a year or as needed, using a pressure washer on a wide fan setting rather than a jet, with a mild detergent.
How long does silicone render last?
Weber says render will last for more than 20 years if it's properly maintained. Figures from different manufacturers vary, and a guarantee depends on the exact product and who applies it, so ask for the guarantee terms in writing for the system being used on your house.
What shortens its life is mostly water from somewhere else: blocked gutters, leaking downpipes, or render running down into the ground where it can wick up moisture. Those are worth fixing before or during the job.
When can it be applied?
Render needs the right weather to cure. Weber's limits for webersil TF are:
- not below 5°C or above 30°C
- not if frost is forecast within 24 hours
- not in damp or wet conditions
- not on walls in direct sunlight or where the wall is hot
That's why rendering work is easiest to plan from spring to early autumn, and why a winter job may need to wait for the right days.
Do you need planning permission to render your house?
Often not. The Planning Portal says rendering can fall under permitted development if the materials look similar to those the house was built with, and replacing render with render of a similar appearance is fine too.
- Conservation areas: you need to apply before cladding the outside of a house with render.
- Listed buildings: you need listed building consent.
- Article 4 directions: some remove the right to paint or render walls without permission.
If you're not sure, ask your council or apply for a lawful development certificate before work starts.
Can it go over existing render?
Sometimes. If the existing render is sound and well bonded, it can often be prepared and coated. If it sounds hollow when tapped, is cracked through or is coming away, the loose sections need cutting out and repairing first, or the wall needs taking back. That's something to check on site rather than decide from a photo.
Planning work like this?
Eli comes to see the job for free and gives you a written, fixed-price quote.
Common questions
Is silicone render better than normal render?
For most houses it's lower maintenance than traditional sand and cement render that needs painting, because it's water-repellent and coloured all the way through.
How long will silicone render last?
Weber says render can last more than 20 years if properly maintained. Ask for the written guarantee terms for the exact system used on your house.
Can you put silicone render over existing render?
Often, if the existing render is sound. Hollow or cracked areas need repairing first.
Does silicone render need painting?
No. It's coloured all the way through, so it doesn't need painting to look finished.
Do I need planning permission to render my house?
Usually not if it looks similar to the existing walls. Conservation areas, listed buildings and some Article 4 areas need permission first.
What's the difference between silicone render and monocouche?
Silicone render is a thin, water-repellent top coat over a base coat. Monocouche is a thick, cement-based coat, usually with a scraped finish.