Code of practice for the application of lime plaster finish

IS 2394: Scope Summary & Key Specifications

Scope:
IS 2394 covers the standards for plastering work, including materials, application methods, repairs, and related safety and quality requirements.

Key Points from IS 2394:

• Definitions: Refer IS 10403-1983 and IS 6508-1972 for terminology (Clause 2.0).
• Plaster Application:
  • One coat plaster method as per Clause 13.2.
  • Repair plaster should be flush and even with existing surfaces (Clause 16.3).
• Scaffolding:
  • Use sound wooden or steel scaffolding per IS 2750-1964 and IS 3696 (Part I)-1966 (Clause 7.2).
• Rounding Off:
  • Follow IS 2-1960 for rounding test and analysis results (Clause 0.4).

SI Units Used (For Design & Testing):

Summary Diagram: Plaster Application Process

flowchart TD
    A[Surface Preparation] --> B[Apply One Coat Plaster]
    B --> C[Finish Surface Flush with Surrounding Plaster]
    C --> D[Allow to Dry]
    D --> E[Inspect & Repair if Needed]

For detailed design formulas or plaster thickness, refer to Clause 13 (not provided here). IS 2394 primarily guides quality and procedural standards for plaster work.

IS 2394 References Summary

• Key Reference IS Codes for Materials:

• Definitions: As per IS 10403-1983 and IS 6508-1972.

• Units & Symbols (SI Units):

• Application of Plaster: Follow one coat plaster method as per Clause 13.2; finish flush with old plaster (Clause 16.3).

Quick Reference Formula

• Force (N):
  [ F = m \times a ] where ( m ) = mass (kg), ( a ) = acceleration (m/s²)

• Pressure (Pa):
  [ P = \frac{F}{A} ] where ( F ) = force (N), ( A ) = area (m²)

flowchart LR
    A[Materials] --> B[Lime (IS 712)]
    A --> C[Pozzolana (IS 1344, 3812)]
    A --> D[Sand (IS 1542)]
    A --> E[Cement (IS 269, 455,

IS 2394: General Requirements & Information Summary

1. Definitions (Clause 2.0)

• Refer IS 10403-1983 and IS 6508-1972 for terminology related to plastering.

2. Materials (Clause 5.1, Table 5)

3. Application (Clause 16.3)

• Plaster repair follows one coat plaster method (see Clause 13.2).
• Finish surface flush and even with existing plaster.

4. Units & Symbols (SI Units)

5. Information Sharing (Clause 3.2)

• Provide all necessary info, drawings, and instructions to plastering personnel.

flowchart TD
    A[Project Info & Drawings] --> B[Plastering Team]
    B --> C[Material Selection per IS Standards]
    C --> D[Plaster Application]
    D --> E[Surface Finish (Flush & Even)]

This ensures compliance with IS 2394 general requirements for quality plastering work.

Scheduling of Plastering Operations (IS 2394 Highlights):

• Interval Between Coats (Clause 4.3):
  Allow sufficient time for each coat to set before applying the next. This prevents cracking and ensures good bond.

• Coordination with Other Works (Clause 4.2):
  Schedule plastering to minimize interference with simultaneous operations (e.g., electrical, carpentry).

• Pre-Work Considerations (Clause 3.1):
  Assess:

  • Surface type & preparation needed
  • Area and finish type
  • Junctions and corners detailing
  • Scaffoldings and protection
  • Fixing accessories embedded in plaster
  • Compatibility with decorative finishes
  • Climatic conditions (rainfall, humidity)

• Mortar Use Timing (Clause 9.7):

  • Use mortar immediately after grinding (same day preferred).
  • Hydraulic lime mortar (Class A): Use within 4 hours.
  • Lime pozzolana mortar: Use within 24 hours.

Key Scheduling Formula (General Practice)

flowchart TD
    A[Start Plastering] --> B[Surface Preparation]
    B --> C{Mortar Prepared?}
    C -->|Yes| D[Apply 1st Coat]
    D --> E[Allow Setting (24-48 hrs)]
    E --> F[Apply Next Coat]
    F --> G{More Coats?}
    G -->|Yes| E
    G -->|No| H[Finishing & Curing]

Summary: Proper scheduling ensures mortar setting and coordination with other trades, optimizing plaster quality and durability.

IS 2394: Materials, Tools and Accessories - Key Points

1. Materials and Relevant IS Codes (Clause 5.1)

2. Storage of Materials (Clause 6.1)

• Lime, cement, and sand must be stored as per:
  • IS 4082-1977 (Storage of cement)
  • IS 7969-1975 (Storage of lime and sand)

3. Tools and Accessories (Clause 5.3)

• Tools for plaster work should conform to IS 1630-1984 (Mason's tools for plaster and pointing).

Summary Table for Quick Reference

Practical Notes:

• Use only materials conforming to the above IS codes for quality assurance.
• Proper storage prevents deterioration, especially for cement and lime.
• Use IS-specified tools to ensure workmanship quality and durability.

flowchart LR
    Materials -->|Lime| IS712
    Materials -->|Pozzolana| IS1344 & IS3812
    Materials -->|Sand| IS1542
    Materials -->|Cement| IS269 & IS455 & IS1489
    Materials -->|Timber| IS1331
    Storage -->|Lime, Cement, Sand| IS4082 & IS7969
    Tools -->|Plaster Work| IS163

IS 2394: Storage of Materials — Key Points

1. Storage of Lime, Cement, and Sand (Clause 6.1)

• Follow IS 4082-1977 and IS 7969-1975 for stacking and storage.
• Materials must be stored in dry, well-ventilated areas.
• Keep cement bags off the ground on wooden planks or pallets.
• Stack height for cement bags should not exceed 10 bags to avoid crushing.
• Lime and sand should be protected from moisture and contamination.

2. Scaffolding Materials Storage (Clause 7.2)

• Wooden scaffolding components must be sound, free from defects.
• Steel scaffolding must conform to IS 2750-1964.
• Thorough inspection and testing before use as per IS 3696 (Part I)-1966.

3. Plastering Mixes (Clause 8.1.3)

• Hydraulic, semi-hydraulic, or fat lime plasters harden by drying and recarbonation.
• Sensitive to shock/vibration during early curing.
• Proper ingredient proportioning and workmanship critical.

Quick Reference Table: Cement Bag Stacking

flowchart LR
  A[Storage Area] --> B[Wooden Planks]
  B --> C[Cement Bags (max 10)]
  A --> D[Lime & Sand Storage]
  D --> E[Moisture Protection]
  A --> F[Scaffolding Materials]
  F --> G[Inspection & Testing]

Summary: Follow IS 4082 & IS 7969 for material stacking; ensure scaffolding materials meet IS 2750 & IS 3696; store cement bags max 10 high on wooden planks in dry areas.

IS 2394: Cleanliness and Maintenance of Tools

Key Specifications (Clauses 7.1 & 7.1.1)

• Clean tools daily: Tools must be scraped and washed after each day's use or operation.
• Metal tools: Clean and apply grease after every use to prevent rust and maintain performance.
• Inspection: Tools must be thoroughly cleaned and examined before starting plastering work.
• Avoid contamination: Contamination by set materials reduces tool life and affects performance.

Related Storage (Clause 6.1)

• Store lime, cement, and sand as per IS 4082-1977 and IS 7969-1975 to avoid contamination affecting tools and materials.

Surface Cleaning (Clause 9.2)

• Background surfaces must be brushed thoroughly to remove dust, loose mortar, and efflorescence before plastering.

Maintenance Checklist:

• Scrape off set material daily
• Wash tools with water
• Grease metal tools post-operation
• Inspect tools before plastering
• Store materials properly to avoid contamination

flowchart TD
    A[End of Work Day] --> B[Scrape Tools]
    B --> C[Wash Tools]
    C --> D{Metal Tools?}
    D -- Yes --> E[Grease Tools]
    D -- No --> F[Store Tools]
    E --> F
    F --> G[Inspect Before Next Use]

Maintaining tool cleanliness ensures durability and quality in plastering work.

Suitability and Characteristics of Lime Plaster (IS 2394)

• Suitability (Clause 8.1.1):
  Lime plaster is highly workable, ideal for internal surfaces. It has a long working time, slow strength gain, and moderate strength.

• Mix Proportions (Clause 12.1.2, Table 2):
  Recommended lime mortar mixes vary; typical lime: sand ratios are around 1:2 to 1:3 by volume for plaster work.

• Thickness of Plaster (Clause 8.7, Table 1):

Key Notes:

• Lime plaster is preferred for its breathability and flexibility.
• Thickness depends on substrate roughness and number of coats.
• Workability and slow setting make lime plaster suitable for delicate restoration.

flowchart TD
    A[Lime Plaster Suitability] --> B[Internal Surfaces]
    A --> C[High Workability]
    A --> D[Long Working Time]
    A --> E[Moderate Strength]
    F[Plaster Thickness] --> G[Brick Masonry]
    F --> H[Stone Masonry]
    G --> I[Single Coat: 15mm]
    G --> J[Double Coat: 10mm + 10mm]
    H --> K[15mm + 10mm (+10mm if very rough)]

General Precautions in Plastering (IS 2394)

Key Points from IS 2394:

• Surface Preparation:

  • Identify surface type to minimize prep.
  • Plan for junctions (doors, windows, ceilings).
  • Decide on cornices, arrises, dado treatments.

• Material Selection & Mixing:

  • Use hydraulic/semi-hydraulic/fat lime mixes with correct proportions.
  • Plaster hardens by drying and recarbonation (slow process).
  • Avoid shocks/vibrations early after application.

• Environmental Conditions:

  • Ideal: gentle warmth + moderate ventilation.
  • Avoid extremes (hot, cold, humid, rainy).
  • Consider rainfall and climatic conditions.

• Work Sequencing & Protection:

  • Scaffoldings must be safe and properly planned.
  • Protect adjacent surfaces during plastering.
  • Avoid design changes after plastering to prevent damage.

• Post-Plastering Care:

  • Avoid damage by careful scheduling of subsequent works.

Typical Mix Proportions (for Lime-Cement Plaster):

Summary Table: Atmospheric Effects on Plastering

flowchart TD
    A[Start Plastering] --> B[Surface Preparation]
    B --> C[Material Selection & Mixing]
    C --> D[Check Atmospheric Conditions]
    D --> E[Apply Plaster]
    E --> F[Protect & Cure Plaster]
    F --> G[Post-Plastering Care]

References:

• IS 2394: General Precautions in Plastering
• IS 1661-1972: Lime Plastering Guidelines
• Safety codes for scaffolding and material handling

IS 2394: Preparation of Background for Plaster Application

Key Specifications (Clauses 11.1, 11.2-11.4)

• Background Preparation is critical for plaster durability.
• Ensure a satisfactory bond between background and first plaster coat.
• Maintain bond throughout the plaster life.
• Follow preparatory steps as per Clauses 11.2 to 11.4 (surface cleaning, roughening, wetting, etc.).

Application Method (Clause 16.3)

• Apply plaster as per one coat plaster work method (see Clause 13.2).
• Finish surface even and flush with surrounding plaster.
• Repair work must blend seamlessly with old plaster.

Necessary Information (Clause 3.2)

• Provide all relevant data and drawings to plastering team.
• Include instructions for preparatory work.

Important Units (SI Units)

Summary Diagram: Background Preparation Workflow

flowchart TD
    A[Existing Surface] --> B[Clean Surface]
    B --> C[Roughen Surface]
    C --> D[Remove Dust]
    D --> E[Wet Surface]
    E --> F[Apply First Plaster Coat]
    F --> G[Finish Even & Flush]

Note: For detailed steps on cleaning, roughening, and wetting refer to Clauses 11.2-11.4 of IS 2394 and IS 10403-1983 for related definitions.

IS 2394: Surface Preparation and Dubbing Out

Key Points from IS 2394:

• Preliminary Inspection (Clause 10.1):
  Ensure surfaces are even and dry before plastering.
  Perform dubbing out in advance to allow adequate drying time before the first undercoat.

• Surface Roughening and Cleaning (Clause 11.3):
  Clean and roughen surfaces as per Clauses 9.1 & 9.2.
  Carry out dubbing as per Clause 9.3 where necessary.

• Dubbing (Clause 9.3):
  Used to fill holes/depressions on uneven backgrounds with the same mortar mix as the first coat.
  Leave patches rough to ensure good bonding with subsequent coats.

Recommended Mix Proportions (Clause 12.1.2, Table 12.2):

Summary:

• Dubbing mortar = first coat mortar mix
• Surface must be dry, even, and roughened before plastering
• Allow adequate curing time after dubbing before applying plaster

flowchart TD
    A[Surface Inspection] --> B{Is surface uneven?}
    B -- Yes --> C[Dubbing with first coat mortar]
    B -- No --> D[Proceed to roughening & cleaning]
    C --> E[Allow drying time]
    D --> E
    E --> F[Apply first coat plaster]

IS 2394: Mixing and Proportioning of Lime Mortar

Key Specifications (Clause 12.1 & 12.1.2)

• Measurement: By volume using gauge boxes.
• Lime quantity measured as lime putty volume. For quick lime/hydrated lime, adjust quantity to yield required lime putty volume.

Recommended Mix Proportions (Table 2)

Mixing Procedure (Clause 12.2.1)

• Mix lime putty and sand on a dry, water-tight platform.
• Add water as needed.
• Feed mixture into mortar mill for grinding (Clause 12.2.3).

Summary Diagram

flowchart LR
    A[Lime (Putty)] --> B[Mixing Platform]
    C[Sand] --> B
    D[Water (optional)] --> B
    B --> E[Mortar Mill Grinding]
    E --> F[Ready Mortar]

Use these proportions and procedures for durable lime mortar as per IS 2394.

IS 2394: Application of Plaster Coats — Key Specifications

Thickness of Plaster Coats (Clause 8.7, Table 1)

Key Points:

• Surface Preparation: As per Clause 1.2, surfaces must be properly cleaned and prepared before plastering.
• Number of Coats: Depends on surface type and condition; single, double, or triple coats.
• Mortar Mix: Lime proportioning varies with coat and surface (details in Clause 1.2).
• Three Coat Work (Clause 13.4):
  • First two coats applied as per Clauses 13.2 & 13.3.
  • Third coat applied to specified thickness and properly cured (Clause 14).

Summary Diagram of Coats Application

flowchart TD
    A[Surface Preparation] --> B{Type of Work}
    B -->|Brick Single-coat| C[Apply 15 mm Single Coat]
    B -->|Brick Double-coat| D[Apply 10 mm First Coat]
    D --> E[Apply 10 mm Second Coat]
    B -->|Stone Masonry| F[Apply 15 mm First Coat]
    F --> G[Apply 10 mm Second Coat]
    B -->|Stone Rough Surface| H[Apply 15 mm First Coat]
    H --> I[Apply 10 mm Second Coat]
    I --> J[Apply 10 mm Third Coat]

This ensures plaster thickness and layering conform to IS 2394 for durability and finish quality.

Curing of Plaster as per IS 2394

• Start curing: 24 hours after plaster finishing (Clause 14.1)
• Duration: Keep plaster continuously wet for 7 days
• Protection: Shield plaster from external damage during curing
• Marking: Dates of plastering must be legibly marked on walls for monitoring curing period

Key Specifications:

• Use water curing only (Clause 13.2.5)
• Protect plaster from drying out or physical damage during curing
• Follow relevant material specifications (cement, lime, sand) as per IS codes referenced in IS 2394

Practical Notes:

• Maintain moisture by sprinkling water or covering with wet sacks/plastic sheets
• Avoid direct sun or wind exposure that can cause rapid drying
• Proper curing ensures strength, durability, and prevents shrinkage cracks

flowchart LR
    A[Plaster finishing] --> B[Wait 24 hours]
    B --> C[Start water curing]
    C --> D[Keep plaster wet for 7 days]
    D --> E[Protect from damage]
    E --> F[Mark plaster dates for monitoring]

This ensures plaster achieves optimum strength and durability as per IS 2394.

IS 2394: Special Finishes - Key Mix Proportions & Specifications

1. Special Finish Mix (Clause 15.3.1)

• Sand: Must be very finely ground.
• Marble: Finely ground and sifted through muslin.
• Preparation: Mix with water, heap, and keep well wetted for 2 days before use.

2. Recommended Mix Proportions for Plaster Coats (Clause 12.1.2, Table 12.2)

3. Surface Finish (Clause 8.8)

• Plasters must be finished to a smooth surface.

Summary

• Special finish uses a rich lime-marble-sand mix.
• Lime class varies by coat; pozzolana may be added for durability.
• Finishing coat (Neeru) is lime and fine sand equally ground.
• Proper grinding and curing (wetting for 2 days) are essential for quality.

flowchart TD
    A[Materials] --> B[Shell Lime (Slaked)]
    A --> C[Fine White Sand]
    A --> D[Powdered Marble]
    B & C & D --> E[Mix as per 12:9:1 volume ratio]
    E --> F[Keep wetted for 2 days]

IS 2394: Repairs and Maintenance Key Points

1. Application of Plaster (Clause 16.3)

• Use one coat plaster method (see Clause 13.2).
• Finish surface even and flush with old plaster.

2. Recommended Mix Proportions for Plaster (Clause 12.1.2, Table 2)

3. Care After Plastering (Clause 4.4)

• Avoid damage by careful programming and no last-minute changes.
• Protect plaster during subsequent operations.

Supplementary Notes:

• Store lime, cement & sand as per IS 4082-1977 and IS 7969-1975.
• Use appropriate tools and maintain them properly (Clause 7).

Summary Diagram: Plaster Application Process

flowchart TD
    A[Surface Preparation] --> B[Apply Dubbing & First Coat]
    B --> C[Apply Second Coat]
    C --> D[Apply Neeru Finishing Coat]
    D --> E[Ensure Even & Flush Finish]
    E --> F[Protect Plaster During Further Work]

This ensures durable, well-bonded plaster repairs as per IS 2394 standards.