How it's done
Sand and cement render goes on in two coats, sometimes three on a very uneven wall.
The first is the scratch coat. It's applied to the prepared wall, levelled off and then scored across with a scratcher while it's still green, which gives the next coat something to grip. A waterproofing additive is often mixed into this coat.
Once the scratch coat has gone off, the top coat goes on, ruled flat and worked to the finish you want. Together the coats usually come to around 20mm, though that varies with how straight the wall is to start with.
There's an old rule with render that still holds: each coat should be no stronger than the one underneath, and the render as a whole shouldn't be stronger than the wall it's on. Get that wrong and the render pulls itself apart as it shrinks, or cracks away from a soft background.
Finishes
| Finish | How it's done | Looks like |
|---|---|---|
| Float finish | Worked with a float as it firms up | A fine, even texture; the most common finish for painting |
| Smooth finish | Trowelled up with a steel trowel | Smooth and flat, but shows imperfections more |
| Textured finish | Worked or thrown for a heavier texture | More rustic; hides minor unevenness |
Most houses end up with a float finish, painted. It's forgiving, it takes masonry paint well and it's easy to touch in later.
Preparation and beads
Like any render, sand and cement is only as good as the wall underneath it. Loose material comes off, the wall is cleaned down, and any cracks or defects in the background are dealt with first. On brick, raked-out joints help with the key. On smooth or dense surfaces, a bonding coat may be needed.
Beads go on before the render: angle beads on external corners, stop beads around windows and doors, and a bellcast bead along the bottom. The bellcast stops the render above the damp-proof course and throws water away from the base of the wall, so it doesn't soak back up behind the render.
Curing: the part people skip
Sand and cement render needs to cure slowly. If it dries too fast in sun or wind, it shrinks and cracks. If it freezes before it's set, it can lose its strength and fail. So it goes on in reasonable weather, it's kept protected while it cures, and in warm, dry spells it may need lightly dampening down.
Fine hairline crazing on the surface isn't unusual and normally disappears under paint. Wider cracks are a different matter and usually point back to the mix, the background or the curing.
Painting
Sand and cement render is almost always painted. Give it time to cure before it's painted; a few weeks is common, but it depends on the weather. Use a breathable masonry paint so moisture in the wall can get out. Then expect to repaint every so often, as with any painted exterior.
Where it works, and where it doesn't
| Good fit | Think twice |
|---|---|
| Concrete block extensions and garden walls | Old solid walls built with soft brick and lime mortar |
| Brick houses with no damp problems | Walls with damp that hasn't been sorted out |
| Matching existing painted render | Lightweight aircrete blocks, unless the mix suits them |
| Repairs to existing cement render | Historic stucco fronts, which need lime |
On older houses, hard cement render is often the wrong material. Walls built with lime need to breathe, and a cement render can trap moisture in them. If we think your walls need a lime-based approach instead, we'll tell you.
Sand and cement or a modern render?
The modern alternatives are through-coloured. Monocouche render and silicone thin-coat render don't need painting, and silicone in particular sheds water well. They do cost more to put on, and they're harder to patch invisibly. Sand and cement is usually cheaper to apply and easier to repair, but you'll be repainting it. If you'd like the pros and cons side by side, see our guide to comparing render types.
Single walls and whole houses
On a single wall or an extension, sand and cement is often the natural choice when the rest of the house is already painted render, because once everything is painted the same colour the join largely disappears. See our page on rendering extensions and single walls. For a full re-render, see rendering a whole house.
Planning permission
Re-rendering like for like doesn't usually need permission, but changing the look of a house can, especially in a conservation area or on a listed building. Planning Portal explains when rendering needs planning permission.
Frequently asked questions
Does sand and cement render need painting?
Usually, yes. It's painted once it has cured, with a breathable masonry paint, and repainted every so often.
How many coats does it need?
Normally two: a scratch coat and a top coat. A very uneven wall may need an extra coat to level it.
Why does sand and cement render crack?
Usually because the mix was too strong, it dried out too fast or it froze before it set. Movement where two different walls meet can also crack it.
Is it suitable for older houses?
Not always. Older solid walls built with lime often need a breathable, lime-based render instead.
Can you repair existing sand and cement render?
Yes. Blown or cracked areas can be cut out and patched. See our render repairs page.
Are your quotes free?
Yes. Send us a few photos of the walls and we'll come back to you with a free quote.
Considering a traditional render?
Tell us about your walls and send a photo or two. We'll let you know whether sand and cement is the right choice and give you a free quote.
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