Guide
Silicone, monocouche or acrylic render?
Silicone render is a thin, water-repellent, vapour-open finish that stays clean longest and is the usual finish over insulation. Monocouche is a thicker one-coat cement render suited to new blockwork. Acrylic is flexible and colourful but less breathable. Lime is the breathable choice for old solid walls.
At a glance
| Render | Thickness | Breathability | Guide cost | Best for |
|---|---|---|---|---|
| Silicone | 1–2mm finish | High | £55–£85/m² | EWI, most masonry |
| Monocouche | 15–20mm | Medium | £45–£70/m² | New blockwork |
| Acrylic | 1–2mm finish | Lower | £50–£78/m² | Extensions, boards |
| Lime | 15–25mm | Very high | £65–£110/m² | Old solid walls |
Which stays cleanest?
Silicone, generally, because water beads off and the surface dries quickly, leaving less for algae to grow on. Any render can go green on a shaded, damp wall.
Which should go on an old house?
On solid walls built with lime mortar, a breathable finish — lime, or a mineral or silicone system on a suitable base — is safer than cement or acrylic, which can trap moisture.
Questions
Can monocouche go over insulation?
No — insulation systems use a mesh base coat and a thin-coat finish.
Is silicone worth the extra?
Usually, for the cleaner, longer-lasting finish.
What is mineral render?
A thin-coat cement- or lime-based finish, usually painted, often used on mineral wool systems.