Acrylic Render vs Silicone Render

What the two finishes actually are

Both are thin-coat, through-coloured renders. They go on as the final layer of a system: a base coat with reinforcing mesh bedded in, a primer, then a textured top coat usually one to two millimetres thick. The colour is in the material, so neither needs painting when new.

The difference lies in the binder. Acrylic render is bound with acrylic resin, which makes it tough and slightly flexible but relatively closed to water vapour. Silicone render adds silicone resin, which makes the surface water-repellent while leaving the pores open enough for moisture inside the wall to escape as vapour.

Side-by-side comparison

The table puts the practical differences in one place. Prices are the per m² figures already published on the rendering page; everything else is general behaviour of the two material types.

Acrylic render compared with silicone render. Factor | Acrylic render | Silicone render. Main quote factors — Preparation, colour and area — Preparation, system, texture and area; Breathability — Lower; holds more moisture in the wall — Higher; lets vapour escape; Rain and dirt — Tends to hold dirt on damp elevations — Water-repellent, rain washes the surface; Algae on shaded walls — More prone to green staining — More resistant; Colour range — Very wide — Wide; Best suited to — Sunny, well-drained walls where budget leads — North- and east-facing or shaded walls, long-term value Scaffolding, preparation, base coat, mesh and beading are common to both systems and often make up much of the total.

Why breathability matters on older houses

Walls take on moisture from rain, from the ground and from the rooms inside. If a finish slows the escape of that moisture, it tends to collect behind the coat, which can show up as damp patches indoors, bubbling or, in cold weather, frost damage at the surface.

Solid-wall houses without a cavity are the most sensitive. On those, the rendering page recommends silicone-silicate, which is more breathable again. Acrylic is generally a poor match for solid walls because of this.

Dirt, algae and how the wall looks in five years

The most common complaint about a render finish is green or black staining, usually on the shady side of the house or under trees. Silicone's water-repellent surface means rain runs off and carries dirt with it, and the wall dries faster, which gives algae less chance to establish.

Acrylic is more likely to stay damp for longer after rain and to hold airborne dirt. On a bright, open elevation that difference can be minor. On a north-facing wall near woodland it tends to be obvious within a few seasons. The separate guide on green algae staining explains cleaning and prevention in more detail.

When acrylic is the sensible choice

Acrylic is not a bad product; it is simply a narrower fit. It makes sense where the budget is the main constraint, the substrate is a modern cavity wall in good order, the elevation gets sun for much of the day and there is no overhanging vegetation. Its flexibility and broad colour range are genuine advantages.

It is also a reasonable choice for smaller areas such as a garage or garden wall, where the saving matters more than the long-term appearance.

Questions to ask before choosing

Whichever finish is quoted, a few questions tell you whether the specification suits the house.

Which way does each elevation face, and how shaded is it? · Is the wall solid or cavity, and is there any existing damp? · Is the existing surface sound, or does old render need removing first? · Which manufacturer's system is being used, and is a system warranty available? · Are base coat, mesh and beading included in the price?

Frequently asked questions

Is silicone render better than acrylic?

For most houses, yes. Silicone is more breathable and water-repellent, so it stays cleaner and handles damp, shaded walls better. Acrylic is cheaper and fine on sunny, well-drained walls.

How much more does silicone render cost than acrylic?

Silicone is usually the higher-specification finish, but scaffolding, repairs, preparation, base coat, mesh and beading are common to both. The walls need inspecting before the difference can be priced reliably.

Can acrylic render be used on an old solid-wall house?

It is generally not recommended, because acrylic is relatively closed to water vapour and can trap moisture in a solid wall. Silicone-silicate is the usual recommendation for those properties.

Does acrylic render go green?

It is more prone to algae than silicone, especially on shaded or north-facing walls, because it stays damp for longer after rain.