Every village around here has one: the handsome old house whose base is blistering and flaking, five years after somebody rendered it in a good strong cement mix. The material was not cheap. It was simply wrong for that wall.
In brief
- Match the render to the wall, not to the catalogue.
- Cement on an old solid wall traps damp inside.
- Through coloured render saves a repainting cycle.
- Never take a pressure washer to a rendered plinth.
- 1 What the coating actually does for you
- 2 The five materials, and the wall each one suits
- 3 The mistake that costs the most: breathability
- 4 Colour: pigment in the mix, or paint on top
- 5 When to apply it, and when to put the trowel down
- 6 Maintenance, and the tool to keep away from it
- 7 The paperwork, if the house is in France
What the coating actually does for you
A render works as a sacrificial layer. Rain, salt air and thirty summers of ultraviolet hit the coating instead of the masonry underneath, and when it eventually tires you renew a few centimetres of mortar rather than a wall. On the plinth, the strip closest to the ground, it also takes the splash from every downpour and the knocks from garden tools, which is why that band wears out first.
The cosmetic job is real too. A render hides the patchwork of blocks, repairs and old openings that most façades accumulate, and it is the one intervention that changes the whole character of a house in a weekend of work per elevation.
The five materials, and the wall each one suits
Choosing a render is not a ranking exercise, it is a matching exercise. The question is what your wall is made of and how it handles moisture.
| Type | Suits | Watch out for |
|---|---|---|
| Cement based | Modern blockwork and cavity walls | Rigid and low in vapour permeability, so it cracks with movement and traps moisture in older masonry |
| Lime | Pre 1919 solid walls, soft stone, listed buildings | Slower to cure and less forgiving of a rushed schedule |
| Acrylic or synthetic | Sound modern substrates, insulated façades | Applied in two stages, and the finish depends heavily on the base coat under it |
| Clay | Sheltered elevations, earth or rubble walls, rustic finishes | Erodes under driving rain unless properly detailed and protected |
| Crushed stone or pebbledash | Exposed façades that take a beating | Very hard to patch invisibly, and it holds dirt in a marine atmosphere |
Cement is the accessible option and it is genuinely the right one on a modern block wall. Lime is the option that saves an old building. Acrylic buys durability on a sound modern substrate. Clay is the natural choice where the weather is kind to it. Crushed stone is the toughest and the least repairable.
The mistake that costs the most: breathability
This is the one worth reading twice. Historic England’s advice on traditional buildings sets out the principle clearly: solid walls are built from permeable materials, they absorb moisture and then release it again once conditions dry out, and modern impervious finishes lock that moisture in instead. Lime cures by carbonation and ends up full of microscopic pores, so water vapour passes through and the wall dries outwards.
A cement render behaves in the opposite way. It has low vapour permeability, so the moisture that inevitably gets into a solid wall cannot leave through the face and travels inwards instead. That is the damp patch on the inside of a beautifully rendered façade. On soft old masonry it goes further: the render is harder than the stone or brick behind it, so movement stress goes into the masonry and the face of the material spalls off.
Rule of thumb before ordering anything: a house built before roughly 1919 with thick solid walls asks for lime. A cavity wall house from the second half of the twentieth century onwards is comfortable with cement or a synthetic system.
Colour: pigment in the mix, or paint on top
Both work, and they commit you to different futures. A through coloured render carries its pigment all the way through, so a chip shows the same shade rather than a pale scar, and there is no repainting cycle to plan for. That is the option I would take on a plinth, which is exactly where knocks happen.
Painting afterwards gives you a far wider palette and the freedom to change your mind in ten years. It works, provided the paint is compatible with the render: a lime or mineral render wants a breathable mineral paint, and covering it with a film forming plastic paint recreates the trapping problem described above. If you are weighing up doing that part yourself, the same honest arithmetic applies as for interior work, and I went through it in detail when I looked at painting your own walls rather than calling a decorator.
When to apply it, and when to put the trowel down
Render fails more often from the weather on the day than from the mix. Avoid frost, avoid applying onto a wall in full afternoon sun, and avoid a windy day: all three dry the surface faster than the material can cure, and the result is a fine crazing that shows up a month later.
Dampen an absorbent substrate before you start, work an elevation at a time so there is no visible joint, and keep the fresh coat protected while it sets. This is also the point where honesty about the job matters. A low plinth is a reasonable weekend project. A full storey means scaffolding, and working at height is where DIY renovation accidents happen.
Maintenance, and the tool to keep away from it
Cleaning is deliberately gentle. Wet the surface with a garden hose, work with a soft brush, rinse. Keep the pressure washer in the shed: a strong jet erodes the surface of the render, opens hairline cracks and drives water into the wall, which is the exact opposite of what the coating is for. Skip cleaning products containing alcohol or solvents as well.
Hairline crazing is usually cosmetic. Cracks you can slide a coin into, render sounding hollow when tapped, or material crumbling in your hand are structural signals: get a specialist to look before you patch, because a render is often the messenger rather than the problem.
The paperwork, if the house is in France
A straightforward ravalement, renewing the coating as it was, is exempt from a déclaration préalable under article R.421-17 of the code de l’urbanisme. Two situations change that. Article R.421-17-1 brings ravalement back under prior declaration inside a site patrimonial remarquable, in the abords of a monument historique, and wherever the local council has passed a reasoned deliberation requiring it. And a change of colour, texture or material is a modification of the building’s exterior appearance, which needs a déclaration préalable in its own right.
Local planning documents frequently impose a range of permitted façade tones, so a phone call to the mairie before ordering ten bags of coloured render is five minutes well spent.
Buying the house before you render it?
A tired plinth is one of the things worth inspecting properly before signing anything on an older property.
Published on 18 August 2026. Sources consulted in August 2026: Historic England guidance on breathable renders for solid walls, articles R.421-17 and R.421-17-1 of the code de l’urbanisme (Légifrance).
