External Rendering in London: Types, Costs & What to Expect
External rendering — applying a continuous finish to the external walls of a building — is widely used on London extensions, rear elevations, and full external refurbishments. Choosing the right render system matters for appearance, durability, maintenance requirements, and performance.
Types of External Render
Sand and cement render (traditional): The classic external finish — a mix of sand and Portland cement applied in two or three coats over masonry or mesh. Low material cost, robust, but cracks over time as the building naturally moves and requires redecoration every 5–10 years. Breathability is limited — not ideal over solid brick walls where moisture management is important.
Monocouche render: A factory pre-mixed through-colour render applied in a single coat. Available in a wide colour palette. Lower maintenance than sand-and-cement (the colour runs through the thickness, so surface damage is less visible). Better crack resistance than traditional render.
Acrylic/silicone render (thin-coat): Applied as a thin finish (typically 3–6mm) over an EPS (expanded polystyrene) insulation base or directly over sand-and-cement base coat. Highly flexible, crack-resistant, hydrophobic (water-resistant), and available in a vast colour range. The standard finish for External Wall Insulation (EWI) systems. The premium external render choice for a maintenance-free finish.
K-Rend / through-coloured mineral renders: Popular resin-modified renders with good flexibility and colour retention. Popular for contemporary new-build aesthetics — smooth or scraped textures.
Render on Extensions
Render is commonly used on extensions to contrast with the brick of the main house, to create a contemporary aesthetic, or to cover blockwork that would otherwise need to be faced. Common choices:
- White or off-white silicone render on contemporary flat-roof extensions
- Monocouche in a natural colour on extensions designed to match or complement the main house
- Through-coloured sand-and-cement for lower-budget projects
Cost of External Rendering in London
| Render type | Approximate cost per m² (supply and fix) |
|---|---|
| Sand and cement render (3-coat, painted) | £45–£80 |
| Monocouche through-colour render | £60–£100 |
| Acrylic/silicone thin-coat (over base coat) | £70–£120 |
| EWI system with silicone render finish | £90–£160 |
Costs depend on surface area, accessibility, substrate preparation, and local labour rates.
Maintenance
Silicone and monocouche renders typically require minimal maintenance for 15–25 years. Sand-and-cement render requires repainting every 5–10 years and crack repairs as needed. Inspect annually — crack and fill early to prevent water ingress.
RCB Design & Build
RCB Design & Build specifies and delivers external rendering as part of extension and full external refurbishment projects across London — advising on the appropriate render system for each substrate and location.