Sand and Cement Screed Calculator

Screed Calculation Formulas:

\[ \text{Cement (kg)} = \left[\text{Area (m²)} \times \text{Thickness (m)} \times 1.33 \times \left(\frac{1}{1 + \text{ratio}}\right)\right] \times 1440 \] \[ \text{Sand (kg)} = \left[\text{Area (m²)} \times \text{Thickness (m)} \times 1.33 \times \left(\frac{\text{ratio}}{1 + \text{ratio}}\right)\right] \times 1600 \]

Cement Required:

Sand Required:

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1. What is Screed?

Screed is a thin layer of material (typically cement and sand) applied to a concrete floor base to create a smooth, level surface for final floor coverings. Proper calculation of materials ensures structural integrity and cost efficiency.

2. How Does the Calculator Work?

The calculator uses these formulas:

\[ \text{Cement (kg)} = \left[\text{Area} \times \text{Thickness} \times 1.33 \times \left(\frac{1}{1 + \text{ratio}}\right)\right] \times 1440 \] \[ \text{Sand (kg)} = \left[\text{Area} \times \text{Thickness} \times 1.33 \times \left(\frac{\text{ratio}}{1 + \text{ratio}}\right)\right] \times 1600 \]

Where:

1.33 — Factor accounting for compaction and wastage
1440 — Density of cement (kg/m³)
1600 — Density of sand (kg/m³)
Ratio — Cement to sand proportion (e.g., 1:4 means 4 parts sand to 1 part cement)

3. Importance of Proper Mixing

Details: The correct cement-sand ratio ensures proper strength, workability, and durability of the screed. Too much cement can cause cracking, while too little weakens the structure.

4. Using the Calculator

Tips: Measure area accurately in square meters. Thickness is typically 25-75mm (0.025-0.075m). Common ratios are 1:3 to 1:5 for floor screeds.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical screed thickness?
A: Domestic floors: 50-65mm. Commercial: 75-100mm. Minimum thickness is 25mm for bonded screeds.

Q2: Why 1.33 multiplication factor?
A: Accounts for material compaction (about 25%) and minor wastage during mixing and application.

Q3: How does ratio affect the mix?
A: Higher sand ratios (1:4-1:5) are more workable but less strong. Lower ratios (1:3) are stronger but harder to work with.

Q4: Should I add water in calculations?
A: Water isn't calculated here as it's typically 4-5 liters per kg cement added gradually to achieve workable consistency.

Q5: How long does screed take to dry?
A: Typically 1 day per mm for the first 40mm, then 2 days per mm thereafter. Full strength takes 28 days.