A traditional floor screed is sharp sand and cement, usually four parts sand to one part cement, mixed fairly dry and laid to a level. The amount comes from the area and the depth.
Per square metre
One square metre at 50 mm is 0.05 m³ of screed. The dry materials take up more room before water is added, so the calculator uses 1.33 times the wet volume. At 4:1 a fifth of that is cement, at 1440 kg/m³, and the rest is sharp sand at 1600 kg/m³.
| Depth | Cement | Sharp sand | Pre-mixed at 2 kg/m²/mm |
|---|---|---|---|
| 40 mm | 15.3 kg | 68 kg | 80 kg |
| 50 mm | 19.2 kg | 85 kg | 100 kg |
| 65 mm | 24.9 kg | 111 kg | 130 kg |
| 75 mm | 28.7 kg | 128 kg | 150 kg |
Bags for a room
A 15 m² floor at 50 mm with 10% waste is 0.825 m³: 316 kg of cement, which is 12.6 bags of 25 kg, so 13, and about 1404 kg of sharp sand, two 800 kg bulk bags.
For 5 m² it is 5 bags of cement and one bulk bag of sand. For 10 m² it is 9 bags and two bulk bags. For 20 m² it is 17 bags and three bulk bags. In Australia, with 20 kg cement and 1 tonne sand bags, the same floors take 6, 11 and 22 bags of cement.
Pre-mixed screed
Bagged screed costs more per square metre but saves mixing. The Easy Mix Traditional Floor Screed data sheet says a 20 kg bag covers about 1 m² at 10 mm, which is 2 kg per square metre per millimetre. At 50 mm that is 100 kg a square metre, five bags, so it suits small areas and patches.
Depth
Measure the depth in several places and use the average; floors are rarely flat before screeding. Bonded, unbonded and floating screeds each have a minimum thickness, and underfloor heating adds its own. Follow the specification for your floor; this page only turns a depth into materials.
Figures are estimates for a shopping list. Check the pack or datasheet before you buy.