Rate Analysis for Plastering — Internal vs External

Introduction

Plastering is a finishing operation applied to brick, stone, or concrete surfaces to provide a smooth, durable surface suitable for painting or decorative finishes. It accounts for a significant portion of the finishing cost in any building project.

This guide provides a complete rate analysis for both internal plastering (12mm thick, 1:6 ratio) and external plastering (20mm thick, 1:4 ratio) per square metre, along with cost comparisons for POP (Plaster of Paris) and gypsum plaster alternatives.

Types of Plaster Finishes

Type	Thickness	Mix ratio	Application
Internal cement plaster	12mm (single coat)	1:6 (CM)	Interior walls and ceilings
Internal cement plaster	15mm (two coats)	1:4 + 1:6	Where smoother finish is needed
External cement plaster	20mm (two coats)	1:4 (CM)	External walls exposed to weather
Neeru (lime) finish	2-3mm	Lime putty	Smooth finish coat over base plaster
POP finish	2-3mm	Plaster of Paris	Smooth finish for painting
Gypsum plaster	11-15mm	Ready-mix gypsum	Internal walls — single coat replacement

Rate Analysis: Internal Plastering (12mm, 1:6 CM)

Material Quantities per Square Metre

Wet volume of plaster per sq m:

• Area = 1 sq m, Thickness = 12mm = 0.012 m
• Wet volume = 1 x 0.012 = 0.012 cum

Dry volume (with 30% bulking factor):

• Dry volume = 0.012 x 1.30 = 0.0156 cum

Cement quantity (1:6 ratio):

• Total parts = 1 + 6 = 7
• Cement volume = (1/7) x 0.0156 = 0.00223 cum
• Cement weight = 0.00223 x 1,440 = 3.21 kg
• Cement bags = 3.21 / 50 = 0.064 bags per sq m

With 5% wastage: 0.067 bags (approximately 0.22 bags per 3.3 sq m, or roughly 1 bag covers 15 sq m).

Sand quantity:

• Sand volume = (6/7) x 0.0156 = 0.0134 cum
• With 10% wastage/bulking: 0.015 cum per sq m

Or roughly 1 cum of sand covers 67 sq m of 12mm plaster.

Material Cost per Square Metre — 12mm Internal Plaster (1:6)

Item	Quantity per sq m	Rate (Rs)	Amount (Rs)
OPC 43-grade cement	0.064 bags	Rs 380/bag	24.32
Sand	0.0134 cum	Rs 3,500/cum	46.90
Water	~3 litres	—	0.50
Materials total			71.72

Labour Cost

Component	Rate per sq m (Rs)
Plastering (mason + helper)	25-35
Scaffolding (if above 3m)	3-5
Curing (7 days)	2-3
Total labour	30-43

Total Rate — Internal Plaster (12mm, 1:6)

Component	Amount per sq m (Rs)
Materials	71.72
Labour (average)	35.00
Sundries (2%)	2.13
Sub-total	108.85
Overhead + profit (15%)	16.33
Total	~125 per sq m

Practical market rate: Rs 28-45 per sq m (labour only) or Rs 100-130 per sq m (material + labour inclusive).

Rate Analysis: External Plastering (20mm, 1:4 CM)

Material Quantities per Square Metre

External plaster uses a richer mix (1:4) and is 20mm thick for weather resistance.

Wet volume per sq m:

• 1 x 0.020 = 0.020 cum

Dry volume:

• 0.020 x 1.30 = 0.026 cum

Cement (1:4 ratio):

• Total parts = 1 + 4 = 5
• Cement volume = (1/5) x 0.026 = 0.0052 cum
• Weight = 0.0052 x 1,440 = 7.49 kg
• Bags = 7.49 / 50 = 0.15 bags per sq m
• With wastage: 0.16 bags per sq m

Sand:

• Sand = (4/5) x 0.026 = 0.0208 cum
• With wastage: 0.023 cum per sq m

Cost Breakdown per Square Metre — 20mm External Plaster (1:4)

Item	Quantity per sq m	Rate (Rs)	Amount (Rs)
OPC 43-grade cement	0.16 bags	Rs 380/bag	60.80
Sand	0.023 cum	Rs 3,500/cum	80.50
Water	~5 litres	—	0.80
Materials total			142.10

Labour Cost

Component	Rate per sq m (Rs)
Plastering (mason + helper)	35-50
Scaffolding erection and removal	8-15
Curing (7 days)	3-5
Roughcast/dash finish (if required)	5-10
Total labour	51-80

Total Rate — External Plaster (20mm, 1:4)

Component	Amount per sq m (Rs)
Materials	142.10
Labour (average)	65.00
Sundries (3%)	6.21
Sub-total	213.31
Overhead + profit (15%)	32.00
Total	~245 per sq m

Practical market rate: Rs 40-65 per sq m (labour only) or Rs 200-260 per sq m (material + labour inclusive).

Comparison Table — Internal vs External Plaster

Parameter	Internal (12mm, 1:6)	External (20mm, 1:4)
Thickness	12mm	20mm
Mix ratio	1:6	1:4
Cement per sq m	0.064 bags (3.2 kg)	0.16 bags (7.5 kg)
Sand per sq m	0.0134 cum	0.023 cum
Material cost per sq m	Rs 72	Rs 142
Labour cost per sq m	Rs 30-43	Rs 51-80
Total rate per sq m	Rs 100-130	Rs 200-260
Cement per 100 sq m	6.4 bags	16 bags
Sand per 100 sq m	1.34 cum	2.3 cum

External plaster costs approximately 1.8 to 2 times more than internal plaster due to thicker application, richer cement mix, and scaffolding requirements.

POP and Gypsum Plaster Alternatives

POP (Plaster of Paris) Finish

POP is applied as a 2-3mm finishing coat over the base cement plaster (not a replacement).

Item	Quantity per sq m	Rate (Rs)	Amount (Rs)
POP powder	1.5-2.0 kg	Rs 12-15/kg	18-30
Labour (application)	—	—	15-25
Sanding and finishing	—	—	5-8
Total POP finish			38-63 per sq m

POP gives a very smooth, paint-ready finish but:

• Adds cost on top of base cement plaster
• Cannot be used in wet areas (bathrooms)
• Develops cracks if base plaster has not cured properly

Gypsum Plaster (Single Coat)

Gypsum plaster is a complete replacement for internal cement plaster — applied directly on brick/block surfaces in a single coat of 11-13mm.

Item	Quantity per sq m	Rate (Rs)	Amount (Rs)
Ready-mix gypsum plaster	10-12 kg	Rs 8-10/kg	80-120
Labour (application)	—	—	20-30
Total gypsum plaster			100-150 per sq m

Advantages of gypsum plaster:

• No curing water required (saves 7-14 days of curing labour and water)
• Smoother finish — eliminates POP layer
• No shrinkage cracks
• Sets in 24-48 hours (faster project completion)
• Better fire resistance

Limitations:

• Not suitable for external walls or wet areas
• Higher material cost than cement plaster
• Requires trained applicators

Cost Comparison Summary

Plaster system	Cost per sq m (Rs)	Curing	Finish quality
Cement plaster 12mm (1:6)	100-130	7 days	Needs POP/putty for painting
Cement plaster + POP finish	138-193	7 days + 1 day	Smooth, paint-ready
Gypsum plaster 12mm	100-150	No curing	Smooth, paint-ready
Cement plaster + wall putty	125-170	7 days + 1 day	Smooth, paint-ready

IS Code References

• IS 1661:1972 — Code of practice for application of cement and cement-lime plaster finishes. Specifies surface preparation, thickness, mix ratios, and curing requirements.
• IS 1270:2007 — Specification for gypsum plaster. Covers setting time, fineness, and compressive strength requirements.
• IS 2250:1981 — Code of practice for preparation and use of masonry mortars. Applicable to plastering mortars as well.
• IS 1200 Part 12 — Measurement of plastering work in square metres, categorised by thickness and mix ratio.

Wastage Factors

Material	Normal wastage	Wastage on uneven surfaces
Cement	3-5%	8-10%
Sand	8-10%	12-15%
POP	5-8%	10-12%
Gypsum plaster	5-8%	10-15%
Water	10%	15%

Uneven brick or block surfaces (out-of-plumb walls, honeycombed concrete) can increase plaster thickness by 5-10mm in patches, raising material consumption by 15-20%.

Practical Tips

1. Wet the surface before applying cement plaster — dry bricks absorb moisture from mortar, causing poor bonding and cracks.
2. Chicken mesh on concrete-brick junctions — Apply galvanised chicken mesh (Rs 8-12/sq ft) at junctions of RCC and brickwork to prevent crack propagation.
3. External plaster in two coats — Apply 15mm base coat first, scratch the surface, wait 24 hours, then apply 5mm finish coat. Single-coat thick application leads to sagging and cracking.
4. Avoid plastering in extreme heat — Summer temperatures above 40 degrees C cause rapid moisture loss. Plaster early morning or late evening, and cure immediately.
5. Use waterproof plaster externally — Add waterproofing compound (Sika, Dr. Fixit) at Rs 3-5/sq m extra for external walls exposed to rain.

Next Steps

• Rate Analysis for Brickwork — Per cubic metre costing for brick masonry
• Introduction to Estimating and Costing — Fundamentals of construction estimation
• Labour Rates India 2026 — Current wage benchmarks across India