Materials Quantity Measurement for Plaster Works
Below is a concise, practical guide with formulas, standard assumptions, material‑per‑volume rates, a worked example, and a ready BOQ table you can apply directly on site.
Key
Steps and Formulas
- Measure area:
total surface area to be plastered minus openings.
- Choose thickness:
typical values — 12 mm for internal walls, 15 mm for
external walls.
- Compute wet volume
using:
Wet Volume=A×t
where A is area in m² and t is thickness in metres (e.g., 12 mm = 0.012 m).
- Convert to dry volume
(allowing for bulking, voids, and wastage):
Dry Volume=Wet Volume×1.33
(Use factor 1.30–1.35
depending on sand moisture and site practice).
Typical
Material Quantities per 1 m³ Dry Plaster Volume
|
Mix
Ratio |
Cement
(bags 50 kg) |
Cement
(kg) |
Sand
(m³) |
|
1:4 |
8.5 |
425 |
0.80 |
|
1:5 |
7.0 |
350 |
0.90 |
|
1:6 |
6.0 |
300 |
1.00 |
Values are standard practical
estimates used by calculators and civil‑engineering references. Adjust for
local material specific gravity and site wastage.
Worked
Example
Given: A=100 m2, t=12 mm=0.012 m, mix 1:4.
- Wet volume:
Wet Volume=100×0.012=1.2 m3
- Dry volume (factor 1.33):
Dry Volume=1.2×1.33=1.596 m3≈1.60 m3
- Cement (bags):
Cement bags=1.60×8.5=13.6 bags≈14 bags
- Sand:
Sand=1.60×0.80=1.28 m3
These steps follow standard plaster
calculators and field practice.
Ready
BOQ Template (per 1 m² at 12 mm and for the Example 100 m²)
|
Item |
Unit |
Qty
per 1 m² (12 mm) |
Qty
for 100 m² |
|
Wet plaster volume |
m³ |
0.012 |
1.20 |
|
Dry plaster volume (×1.33) |
m³ |
0.016 |
1.60 |
|
Cement (1:4) |
bags 50 kg |
0.136 |
13.6 ≈ 14 |
|
Sand (1:4) |
m³ |
0.008 |
1.28 |
(Quantities rounded for procurement;
keep 5–10% extra for site wastage.)
Practical
Notes and Assumptions
- Thickness:
use project specification; ceilings often 10 mm, external 15–20 mm.
- Dry conversion factor:
use 1.30–1.35 depending on sand moisture and grading.
- Mix selection:
1:4 for external or high‑strength finish; 1:5–1:6 for internal non‑critical
finishes.
- Wastage:
add 5–10% extra to final procurement quantities for handling losses
and uneven surfaces.
- Site verification:
measure actual surface area on site and confirm sand specific gravity
before final ordering.
How to Ensure Quality Plaster Works?
Ensure durable, crack‑free plaster by preparing the substrate, using correct mixes and tools, applying controlled two‑coat techniques, and curing for at least 7–10 days—especially in Dhaka’s humid climate, where thorough wetting and extended curing reduce debonding and efflorescence.
Quick checklist (what to do first)
Assess substrate: confirm masonry/RCC is cured and free of dust, oil, loose mortar, and efflorescence.
Provide mechanical key: hack or roughen smooth concrete; rake mortar joints 10–15 mm for masonry.
Wetting: dampen surfaces to SSD (saturated surface dry) before plastering to prevent rapid suction.
Step‑by‑step procedure (practical)
Pre‑work inspection
Verify masonry cured ≥7 days (longer in hot/dry or variable humidity conditions).
Check scaffolding, MEP chases, and openings are ready.
Materials & mix control
Use clean potable water, fresh cement, and washed sand (silt ≤5%).
Follow specified mix ratios (typical Cement: Sand 1:4 or 1:5 for internal plaster; external mixes per spec).
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