Guide
Which render, and do you need permission
Sand and cement, monocouche and silicone thin-coat behave differently, cost differently and last differently. And rendering a house is not always permitted development.
The three systems
Sand and cement is the traditional one: two or three coats of mixed sand, cement and lime, ruled to beads and finished. It is the cheapest at £45 to £75 per square metre, it is hard, and it needs painting and repainting because the colour is on the surface rather than in it.
Monocouche is a through-coloured dry powder mixed on site and applied in one pass at around fifteen millimetres. £55 to £80 per square metre, no painting, and unforgiving of a batch difference because the colour is in the mix.
Silicone thin-coat is a polymer basecoat with mesh embedded in it and a thin coloured topcoat over. £65 to £95, no painting, more flexible than the other two and better at shedding dirt.
Which one suits which wall
The wall underneath decides more than preference does.
On sound blockwork or brick with no damp history, any of the three works, and the choice comes down to budget against never painting again.
On a wall with movement, or an extension meeting an original, the mesh in a silicone basecoat is what stops cracks telegraphing through.
On a solid wall built before about 1919, none of the three is right, because all of them are substantially closed to water vapour. That is a lime render job, and getting it wrong seals moisture into the masonry.
On a wall that is currently damp, none of them is right yet. Find the cause first.
Do you need planning permission
Usually not: rendering a house is normally permitted development.
It is not permitted development if the building is listed, if it is in a conservation area, a national park, an area of outstanding natural beauty or a World Heritage Site, or if a condition attached to the original planning permission removed the right. Some estates also carry covenants in the deeds that have nothing to do with planning.
External wall insulation is more likely to need consent than plain render, because it changes both the appearance and the thickness. Ask the council before the scaffold goes up rather than after.
What scaffold does to the price
Scaffold is £700 to £1,400 for a typical semi and it is a fixed cost whatever area is being rendered. That single fact reshapes most decisions on this page.
One elevation does not cost a quarter of four, because the scaffold is most of the difference. If you are having gutters, fascias, windows or a roof done as well, sharing the scaffold across those trades is worth planning even if it means waiting.
How long it lasts
Sand and cement: twenty to thirty years if it was right when it went on, plus repainting every five to ten. Monocouche and silicone: twenty to twenty-five, with washing down rather than painting.
What actually kills render is water getting behind it through a crack, a failed sill, a blocked gutter or a bridged damp course, and then freezing. Render fails at its details far more often than it fails across the field.
Common questions
Do I need planning permission to render my house?
Usually not; it is normally permitted development. You do if the house is listed, in a conservation area, a national park or an AONB, or if a planning condition removed the right. Check with the council first.
Which render is best?
It depends on the wall. Silicone thin-coat for anything with movement, monocouche for a straightforward blockwork elevation on a budget, sand and cement if you want cheapest and do not mind painting. On a pre-1919 solid wall, lime.
How long does render last?
Twenty to thirty years for sand and cement, twenty to twenty-five for modern systems. Failures are almost always at the details, a crack or a failed sill letting water behind, rather than across the middle of a wall.
Can I render over pebbledash?
Yes, if it is sound and well keyed, and it is usually cheaper than removing it. Tap it first: anything hollow has to come off, and if enough is hollow you are pricing a hack-off instead.