Rendering is the process of levelling a rough or uneven surface — such as brickwork or concrete — by applying a thin layer of mortar or render. The aim is to create a smooth, level surface as a base for further finishing. Rendering is a widely used technique when fitting frames, lintels and sills.
When do you render?
- The top of the brickwork is not level — you apply mortar to bring it to the correct height
- A frame or lintel needs to sit on a flat base
- A concrete floor has irregularities that must be smoothed out before tiling
- After building in a beam, the surrounding brickwork needs to be levelled
Rendering vs. plastering vs. levelling
| Technique | Layer thickness | Purpose |
|---|---|---|
| **Rendering** | A few mm to 1 cm | Locally level or plumb |
| **Plastering** | 5-15 mm | Finish an entire wall smooth |
| **Levelling** | 2-10 mm | Level a floor for finishing |
How do you render?
- Clean and dampen the surface
- Apply a layer of mortar with a trowel
- Strike the layer off with a straightedge to the desired level
- Allow the layer to cure before continuing with the finish
Tips for DIYers
- Use a spirit level to check the result is level
- Work in thin layers — layers that are too thick will crack during curing
- For frames: render to exactly the height of the sill
Related terms
- Mortar mix
- Mortar
- Levelling
- Plastering
- Lintel
- Frame