Plastering Details
Wet Volume—
Dry Volume (× 1.54)—
Cement Bags (50 kg)—
Cement Volume—
Sand Volume—
Sand Weight—
Floor Screed Details
Floor Area—
Wet Volume—
Dry Volume (× 1.54)—
Cement Bags (50 kg)—
Cement Volume—
Sand Volume—
Sand Weight—
Screed thickness of 40 mm is standard for domestic floors. Ensure subbase is clean, sound and properly prepared before laying.
Brickwork Mortar Details
Wall Volume—
Mortar Volume (10% of wall)—
Dry Volume (× 1.54)—
Cement Bags (50 kg)—
Cement Volume—
Sand Volume—
Sand Weight—
Mortar is assumed to be 10% of total wall volume (brick + mortar). Actual proportion may vary by brick size and joint thickness (typically 10–12 mm joints).
Plain Cement Concrete (PCC) Details
Area—
Wet Volume—
Dry Volume (× 1.54)—
Cement Bags (50 kg)—
Cement Volume—
Sand Volume—
Sand Weight—
Aggregate Volume—
Aggregate Weight—
M15 (1:2:4) is the minimum grade recommended for PCC under footings and foundations. M10 (1:3:6) is used only for lean concrete bed or blinding layers.
Dry Volume Correction Factor Explained
When cement and sand are mixed dry, the total volume appears larger than the final wet (mixed with water) volume. This is because water fills the voids between particles, causing the mix to compact. The dry volume factor of 1.54 means that to produce 1 m³ of wet mortar you need to start with 1.54 m³ of dry materials.
- Wet volume = area × thickness (m)
- Wet volume with wastage = wet volume × (1 + wastage / 100)
- Dry volume = wet volume × 1.54 (mortar) or × 1.54 (concrete)
For a 1:N mortar mix: total parts = 1 + N. Cement volume = dry volume × 1/(1+N). Sand volume = dry volume × N/(1+N).
Mortar Mix Ratios for Different Applications
| Application | Recommended Mix | Notes |
|---|---|---|
| Internal wall plaster | 1 : 6 | General internal walls, gives smooth finish |
| External wall plaster | 1 : 4 | Weather-exposed surfaces, stronger mix needed |
| Ceiling plaster | 1 : 3 | Richer mix for overhead work, less sagging |
| Floor screed | 1 : 4 | Standard domestic screed, 40–50 mm thick |
| Brickwork mortar | 1 : 5 to 1 : 6 | Load-bearing walls use 1:5, partition walls 1:6 |
| PCC (M10) | 1 : 3 : 6 | Lean concrete, blinding layer below footings |
| PCC (M15) | 1 : 2 : 4 | Minimum structural PCC, under RCC footings |
FAQ
The dry volume factor for mortar is 1.54. This means the dry mix volume is approximately 54% more than the wet volume of mortar. This accounts for voids between sand particles and cement that are filled when water is added. For concrete, the factor is also 1.54 (some references use 1.57).
For floor screed, a 1:4 (cement:sand) mix ratio is most commonly recommended. For lightly loaded areas, a 1:5 mix can be used. For heavy-duty floors, a richer 1:3 mix may be specified. Screed thickness typically ranges from 25 mm to 65 mm depending on the type (bonded, unbonded or floating).
For 100 m² of internal plastering at 12 mm thickness with a 1:6 mix and 20% wastage: wet volume = 1.2 m³; with wastage = 1.44 m³; dry volume = 1.44 × 1.54 ≈ 2.22 m³; sand = 2.22 × (6/7) ≈ 1.90 m³ ≈ 3.04 tonnes. Approximately 9–10 bags of cement (50 kg) and 3–3.5 tonnes of sand are needed.
Mortar is a mixture of cement, sand and water used to bind bricks or for plastering and screeding — it contains no coarse aggregate. Concrete is a mixture of cement, sand, coarse aggregate (gravel) and water, used for structural elements like slabs, beams and columns. Concrete is significantly stronger and is used wherever structural load-bearing capacity is required.