Rendering in London: sand and cement, monocouche and silicone

Published UK guides put supply and fit at £40–£70 per m² for sand and cement, £50–£90 for monocouche and £60–£110 for silicone, before scaffold, removal of old render and skips. Those are national figures, and the same guides say London runs 15–30% above them, with one putting London labour 30–50% higher. Scaffold for a two-storey London house is quoted at £750–£1,600 for a four-week hire. These are September 2026 market ranges, not our quotes, and most do not state their VAT position.

Measure the wall area first: a three-bedroom semi has roughly 80–120 m² of wall once the windows and doors are taken out. One UK guide puts a standard semi in mid-market silicone or monocouche at £6,500–£11,000 at average UK prices, or £9,500–£15,500 in London; another puts a typical three-bed semi, whatever the system, at £7,000–£15,000. Check whether a total includes scaffold, hack-off of old render at £15–£30 per m² and a skip at £300–£425 plus the road permit. A terrace with only a rear elevation is a fraction of that; a detached house is more than double.

K Rend is a brand of monocouche, or one-coat, render. Published UK guides put monocouche supplied and fitted at £50–£90 per m², with the branded K Rend and Weber systems quoted at the top of that or a little above, at £80–£115 per m² in one guide. The extra cost over a plain sand and cement coat buys a through-coloured finish that never needs painting, which over ten or fifteen years usually costs less than repainting cement render every few years. London prices sit above the national figures.

Spring to early autumn, in weather that is neither freezing nor baking. Render needs to cure slowly: applied in frost it fails, applied into direct summer sun or a hot wind it dries too fast and cracks, and rain on a fresh coat washes the finish. Manufacturers set a minimum temperature for their systems and we work to it, which means a March start can slip a week and an August job may be worked in the shade of the day. The wall should also be dry before it is coated, so a wet winter delays a spring start.

Some can and most think they can, which is the problem. Internal plastering and external rendering share tools and not much else: render has to cope with rain, frost, sun and the movement of the building, and it fails at the details, the beads, bell casts, sills and junctions, rather than in the flat areas a plasterer is good at. A monocouche or silicone system also has to be applied to the manufacturer's method to keep its guarantee. Ask who has done the last three rendering jobs and whether you can see them.

It depends on the street. On a house whose brickwork is tired, patched or already rendered, a well-applied modern render transforms the front and protects the wall, and buyers respond to that. On a street of clean Victorian brick, rendering the only house that was not rendered can make it the odd one out and is the sort of change a conservation area will refuse. Render also commits the next owner to maintaining it. Weigh the state of the brick, the neighbours and the maintenance before the colour chart.

A sound render on a sound wall lasts decades; age alone is rarely why it comes off. Render is replaced when it has blown, meaning it sounds hollow because it has parted from the wall, when it is cracked and letting water in behind it, or when the wall underneath needs work that cannot be done through it. Painted sand and cement wants repainting every few years to stay weathertight; monocouche and silicone want washing rather than painting. Tap the wall each spring and deal with hollow patches before a winter gets behind them.

Not on its own, and on the wrong wall it makes damp worse. Render keeps rain off the face of a wall, so it helps with penetrating damp through porous or cracked brick, but it does nothing for rising damp, a leaking gutter or condensation, and a hard cement coat on an old solid wall traps the moisture the wall used to breathe out. The survey has to find the cause first; then the system is chosen to suit it, which on a pre-1900 wall usually means a breathable coat rather than a cement one.

On new work, a rendered blockwork wall is usually cheaper than a facing-brick one because blocks are laid faster and the render replaces the skilled pointing. On an existing house the question is different: rendering over sound brick is a choice about appearance and weather protection, not a saving, and repairing and repointing good brick is often cheaper than covering it. Where the brick is soft, patched or already rendered, render is the practical route. We will tell you which case your wall is before we quote.

Rendering over hollow or damp old render instead of taking it off. Putting a rigid cement coat on an old solid wall that needs to breathe. Taking the render down over the damp-proof course so it bridges it. Leaving out beads, bell casts and movement joints so the first crack has nowhere to go. Applying in frost or full sun, or before the base coat has cured. Sealing frames badly so water gets behind the coat at the windows. Almost all of them are invisible on the day and obvious two winters later.

Not usually. Outside protected areas, rendering a house is permitted development provided the finish looks similar to the existing house. In a conservation area, a national park, an area of outstanding natural beauty, the Broads or a World Heritage Site, cladding a house with render needs a planning application, and a listed building needs listed building consent for any significant external work. Building control is a separate question: re-rendering 25% or more of a wall can trigger a requirement to upgrade its insulation, so ask before you assume.