Render protects walls from the weather and has a big effect on how a house looks. In Cornwall, where wind-driven rain, salt air and damp winters are the norm, choosing the right render for your walls matters as much as choosing a colour. The wrong choice can crack, stain or trap moisture in the wall.
This guide compares the main types of render used on Cornish homes, explains what suits different wall types, and covers planning, Building Regulations and general cost guidance. If you own an older stone or cob property, our dedicated guide to lime rendering and pointing goes into more detail on lime.
Start with the wall, not the finish
The most important question is what the wall is made of and how it handles moisture:
Solid stone, cob and older brick walls: most pre-1920s Cornish homes have solid walls without a cavity. These walls absorb some moisture and need to be able to dry out, so a breathable (vapour-permeable) render is usually needed.
Modern blockwork and cavity walls: most houses built from the mid-twentieth century onwards have block or cavity walls. These can take a wider range of modern renders.
Mundic block homes: some Cornish homes built with mundic concrete blocks need specialist advice before any work to the walls. See our guide to mundic block homes.
If you are not sure what your walls are, a builder or surveyor can check before you choose a render.
The main types of render
Lime render
Lime render is the traditional finish for Cornish stone and cob buildings. It is breathable and slightly flexible, letting moisture escape and coping with small movements. It is usually applied in several coats, takes longer to cure and needs protection from frost and heavy rain while it sets. It can be finished with a limewash or breathable mineral paint. It is often the right choice for older and listed buildings.
Sand and cement render
Sand and cement render has been widely used on Cornish houses for decades. It is hard and relatively low cost, but it is brittle and not very breathable. On solid stone walls it can crack, let water in behind and then stop it drying out, which is a common cause of damp in older homes. On sound modern blockwork it can perform reasonably well, but it usually needs painting and repainting over time.
Monocouche render
Monocouche (one-coat) renders are factory-mixed, through-coloured cement-based renders applied in a single thick coat and then scraped back to a textured finish. Because the colour runs through the material, they are not normally painted. They suit modern blockwork and are popular on new builds and extensions.
Thin-coat silicone and acrylic render
Thin-coat systems are applied over a basecoat and reinforcing mesh. The top coat is through-coloured and comes in a wide range of colours and textures. Silicone renders are water-repellent while still allowing some vapour through, and are designed to resist dirt and algae, which can be useful on damp, north-facing or coastal walls. Acrylic renders are similar but less breathable. These systems are also used as the finish on external wall insulation.
Roughcast, pebbledash and Tyrolean
Many Cornish homes from the twentieth century have roughcast or pebbledash. These finishes are hard-wearing but can hide cracks and trap moisture if they fail. Repairs can be hard to match, so a full re-render is sometimes the more practical option.
Cornish weather and render
Wherever you are in Cornwall, render has to cope with a lot of rain driven by strong wind. On the coast, salt adds to the wear. A few points help a render last:
Good detailing: drip beads above windows and at the base of walls, proper sills and flashings, and keeping render above ground level all reduce water getting behind the finish.
Algae and staining: green staining is common on shaded and north-facing walls. Silicone renders and good maintenance can reduce it.
Weather windows: render should not be applied in frost, heavy rain or strong drying winds. Lime in particular needs time and protection. See our guide to building work in winter.
Our guide to weatherproofing coastal homes covers other ways to protect exposed properties.
Planning permission and Building Regulations
Re-rendering a house in a similar style is often possible without planning permission, but there are important exceptions. Under permitted development, materials should generally be of a similar appearance to the existing house. In a conservation area or the Cornwall National Landscape, cladding the outside of a house with render, stone, timber or tiles usually needs planning permission. Listed buildings need listed building consent for most changes. Our guides to building in an AONB or conservation area and planning permission in Cornwall explain more.
Building Regulations can also apply. Replacing render over a large area of wall can count as renovating a thermal element, which may mean the wall's insulation has to be improved where this is practical. Check with Building Control before you start. Our Building Regulations guide explains how this works, and our guide to insulating solid-wall stone houses covers suitable options for older homes.
What does rendering cost?
As general guidance only, rendering is usually priced per square metre, and the total depends on the size and height of the walls, how much old render has to be removed, the condition of the wall underneath, scaffolding, and the system chosen. Lime and thin-coat systems are often more expensive than basic sand and cement, but they can last well when correctly specified. Scaffolding and preparation can make up a large part of the cost. A site visit and written quote are the only reliable way to price your project.
Frequently asked questions
What is the best render for an old stone house in Cornwall?
In most cases a breathable lime render is the safest choice for solid stone and cob walls, because it lets moisture escape. Get advice for your specific building.
Can I render over existing render?
Sometimes, if the existing render is sound and well bonded. Loose, cracked or hollow render usually needs to be removed first.
Do I need planning permission to render my house?
Not always, but it may be needed if the appearance changes significantly, or if the house is in a conservation area, the National Landscape or is listed. Check with Cornwall Council.
Thinking about rendering your home? Talk to us
Cornish Building Company provides render, stone and lime work as part of renovations and new builds across Cornwall. See our stone, rendering and lime work and property renovation services and our areas we cover. Call us on 01208 816991 or contact us to talk through your project.
