How Much Sand and Cement to Render an 8m x 5m Wall?

Rendering an 8 × 5 m wall (40 m²) in a 20 mm coat of 4 : 1 mix needs 14 bags of 25 kg cement and 1.53 tonnes of building sand, with 15% waste. That is 0.92 m³ of render.

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Render needed

0.92 m³

920 litres, with your waste allowance

What to buy

Bags of cement (25 kg)14 bags

Wall area to render: 40.0 m²

Materials to mix

Cement: 344 kg
Bags of cement (25 kg): 14 bags
Building (soft) sand0.96 m³: 1.53 tonnes
Cement per m² of wall: 8.61 kg

Render is put on in two coats on most walls: a base coat of about 10 to 12 mm, and a thinner finishing coat of about 6 to 8 mm, made with a leaner mix. Damp the wall first, and keep the render damp as it cures. Add a plasticiser to the mix if you want it to work more easily, and follow the maker's instructions. This is a planning estimate: sand, moisture and mixing change the quantities. On an old or damp wall, ask a plasterer or a builder.

Before you buy: round up to whole packs, check the size printed on the label, and add a little spare. Your supplier has the final say.

Render for an 8 × 5 m wall

A wall about this high is a two-storey house wall, so you will need scaffolding. The wall is 40 m² with no openings taken off. Counts are for a 20 mm coat in a 4 : 1 building sand to cement mix, with 15% waste.

Render thickness	Wet render	Cement (25 kg bags)	Building sand (tonnes)
10 mm	0.46 m³	7	0.77
15 mm	0.69 m³	11	1.15
20 mm	0.92 m³	14	1.53
25 mm	1.15 m³	18	1.91

Effect of the mix

A richer mix (3 : 1) is stronger and uses more cement. Leaner mixes (5 : 1 or 6 : 1) suit finishing coats and sheltered walls.

Mix (sand : cement)	Cement (25 kg bags)	Building sand (tonnes)
3 : 1	18	1.44
4 : 1	14	1.53
5 : 1	12	1.59
6 : 1	10	1.64

Taking off windows and doors

Openings	Wall to render	Cement (25 kg bags)	Building sand (tonnes)
0 m²	40.0 m²	14	1.53
2 m²	38.0 m²	14	1.45
4 m²	36.0 m²	13	1.38
6 m²	34.0 m²	12	1.30

Use the UK render calculator to enter your own wall, thickness and mix. Render goes on in two coats on most walls, and the wall must be damped and the render kept damp as it cures. Building the wall too? See the bricks for a wall page or the block calculator.

Want to change anything else? The calculator above is the full Render Calculator (UK): Sand and Cement for a Wall: edit any number and the results update instantly.

Tools & materials for this project

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Building sand bulk bag Cement 25 kg Plasticiser for mortar and render Plastering float Corner bead for render

Frequently asked questions

How much sand and cement to render an 8m x 5m wall?

An 8 × 5 m wall is 40 m². For 20 mm of render in a 4 : 1 mix with 15% waste you need 14 bags of 25 kg cement and 1.53 tonnes of building sand. That is 0.92 m³ of wet render.

How much does the thickness change it?

Quantity scales with thickness. At 15 mm the wall needs 11 bags of cement, and at 25 mm it needs 18. Use more for rough or uneven walls.

Do I take off windows and doors?

Yes. Enter the area of any openings you will not render. For example 4 m² of openings brings this wall down from 14 bags to 13 bags.

Related sizes and guides

Related sizes

Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.

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