Code of practice for sound insulation of non-industrial buildings

IS 1950: Scope & Key Specifications for Sound Insulation

• Scope (Clause 0.9):
  Covers technical provisions for sound insulation in buildings. Does not include all contract provisions.

• Rounding Off (Clause 0.8):
  Test values must be rounded per IS 2:1960 rules, retaining the same significant figures as specified.

Sound Reduction Values (Appendix A, Clause 6.2.7)

Notes:

• Floating floors and resilient layers significantly improve sound insulation (up to 55 dB).
• Use airtight layers (e.g., sand, mortar) to enhance sound reduction.

flowchart LR
    A[Continuous Constructions] -->|Sound Reduction| B[20-55 dB]
    C[Semi-Discontinuous Constructions] -->|Sound Reduction| D[30-55 dB]
    B

IS 1950: Noise Definitions & Measurement Key Points

1. Definitions & Reference

• Threshold of audibility: 0 dB (reference sound pressure = 0.0002 dynes/cm²)
• Noise measured in decibels (dB), a logarithmic scale of sound pressure level.

2. Typical Sound Levels (Table I, Clause 2.3.3)

3. Traffic Noise Levels (Table II, Clause 3.1)

4. Noise Measurement Notes

• Noise levels are typically measured at 3 meters from the source for traffic.
• Noise reduction (Clause 6.1) involves design and material selection to mitigate these levels.

Summary Formula for Sound Level (dB):

[ L_p = 10 \log_{10} \left(\frac{p^2}{p_0^2}\right) = 20 \log_{10} \left(\frac{p}{p_0}\right) ]

Where:

• (L_p) = Sound pressure level in dB
• (p) = Measured sound pressure
• (p_0 = 2 \times 10^{-5

IS 1950: Outside Noise Levels - Key Tables & Specifications

1. Typical Sound Levels (Clause 2.3.3, Table I)

2. Traffic Noise Levels (Clause 3.1, Table II)

3. Residential Area Noise Levels (Clause 3.3, Table III)

4. Maximum Acceptable Noise Levels Inside Buildings (Clause 4.1, Table IV)

Summary:

• Outside noise levels vary by source and location, with heavy traffic and industrial areas reaching up to 90 dB.

IS 1950: Maximum Acceptable Noise Levels Summary

1. Maximum Acceptable Noise Levels Inside Buildings (Clause 4.1, Table IV)

2. Typical Residential Area Noise Levels (Clause 3.3, Table III)

3. Typical Sound Levels for Reference (Clause 2.3.3, Table I)

Notes:

• Noise levels are measured in decibels (dB).
• The maximum acceptable noise levels inside buildings are set considering comfort and practical use.
• Residential area noise levels guide external noise insulation requirements.

flowchart LR
    A[Outside Noise] --> B[Building Envelope]
    B --> C[Inside Noise Level]
    C --> D[Acceptable Noise Level]
    D -->|Compare| E{Within Limits?}
    E -->|Yes| F[Comfort & Compliance]
    E -->|No| G[Noise Control Measures]

This diagram shows the flow from outside noise to ensuring

IS 1950: Sound Insulation of Impact Noise - Key Points

1. Impact Insulation Requirements (Clause 5.4)

• Floors immediately above bedrooms/living rooms must provide impact insulation.
• Refer to Clause 5.4.1 and 5.4.2 for specific construction details (not provided here).

2. Recommended Sound Insulation Standards (Table V, Clause 5.1)

*Higher values correspond to concrete, stone, or similar solid floor/ceiling construction.

3. Sound Insulation vs Weight of Rigid Partitions (Clause 6.2.1 & Table VII)

• Sound insulation (Transmission Loss, TL) increases logarithmically with weight per unit area.
• Doubling weight ≈ +4 to 5 dB increase in TL.

Summary:

• Use solid, heavy floor/ceiling constructions to achieve higher impact noise

IS 1950 - Clause 6.2: Sound Insulation

Key Points on Sound Insulation of Non-Porous Rigid Partitions (Clause 6.2.1)

• Sound insulation increases approximately by 4 to 5 dB each time the weight per unit area doubles.
• The relation between weight (kg/m²) and sound insulation (Transmission Loss in dB) is logarithmic.
• Excessive thickness yields diminishing returns in sound insulation.

Table VII: Sound Insulation vs Weight per m²

Approximate Formula:

[ R = R_0 + 10 \log_{10} \left(\frac{m}{m_0}\right) ] Where:

• ( R ) = Transmission loss (dB)
• ( m ) = Weight per unit area (kg/m²)
• ( R_0, m_0 ) = Reference sound insulation and weight

This table guides design choices for wall thickness and materials to achieve desired sound insulation in buildings.

IS 1950 - Noise Control by Building Layout and Orientation

Key Specifications & Guidelines

• Location & Orientation (Clause 6.1.1 & 0.5):

  • Locate residential buildings away from noise sources (industrial areas, railways, busy roads).
  • Set buildings back from roads according to expected noise levels.
  • Orient doors/windows away from noise sources to reduce direct sound entry.
  • Use double doors/windows if orientation away from noise source isn't possible.
  • Consider eliminating windows/ventilators with artificial lighting and mechanical ventilation in very noisy areas.

• Room Arrangement (Clause 6.1.2):

  • Place bedrooms farthest from noise sources.
  • Separate quiet rooms from noisy rooms.
  • Avoid placing mechanical equipment near bedrooms.

Practical Noise Reduction Tips

Conceptual Diagram: Noise Control by Layout

graph LR
A[Noise Source] -->|Sound waves| B[Building]
B --> C[Rooms]
C --> D[Bedroom - Quiet Zone]
C --> E[Living Room - Noisy Zone]
B -.-> F[Setback Distance]
B -.-> G[Orientation away from noise]

Summary: IS 1950 emphasizes strategic building location, orientation, room zoning, and use of double glazing to minimize noise intrusion in residential buildings.

IS 1950: Sound Insulation of Partitions and Materials

1. Sound Insulation of Non-Porous Rigid Partitions (Clause 6.2.1)

• Sound insulation (Transmission Loss, TL) increases logarithmically with weight per unit area (kg/m²).
• Doubling weight increases TL by about 4 to 5 dB.
• Beyond a certain thickness, increasing weight yields diminishing returns.

2. Sound Insulation Classification (Clause 6.2.6, Table VIII)

Summary:

• Use weight per unit area to estimate sound insulation.
• For high privacy, aim for ≥ 50 dB TL.
• Select materials and thickness based on required TL and space use.

flowchart LR
    A[Weight per m²] --> B[Sound Insulation (TL)]
    B --> C{Doubling Weight}
    C -->|+4 to

IS 1950 - Porous Rigid Materials: Key Points & Formulas

1. Sound Insulation Enhancement

• Porous rigid materials (e.g., porous concrete masonry, cinder concrete) provide ~10% higher sound insulation than non-porous materials of the same weight due to sound absorption.
• Recommendation: Plaster porous partitions on at least one side (preferably both) to maximize insulation.

2. Weight vs Sound Insulation (Table VII Not Applicable)

• The standard relation between weight per m² and sound insulation (Table VII) does not apply to porous rigid materials.
• Porous materials' absorption improves insulation beyond weight-based predictions.

3. Composite Constructions

• Non-rigid porous materials (felt, mineral wool) alone provide low insulation.
• Combining rigid materials with porous absorbers yields better insulation per unit weight.

4. Heavy Weight Construction Example

• To achieve ~60 dB insulation:
  • Single wall: ~100 cm thick (1950 kg/m²) non-porous rigid wall OR
  • ~85 cm thick rock wool (80 kg/m³)
• Double wall with 10 cm air gap is more effective than single wall of same weight.
• Porous rigid materials reduce vibration better than non-porous ones.

Summary Table (Conceptual)

flowchart LR
    A[Porous Rigid Material] --> B[Sound Absorption ~10% ↑]
    B --> C[Plaster on 1 or 2 sides]
    A --> D[Reduced Vibration]
    E[Composite Construction] --> F[Rigid + Porous Absorber]
    F --> G[Better Insulation per Weight]
    H[Double Wall + Air Gap]

IS 1950 - Porous Flexible Materials: Key Points & Formulas

1. Sound Insulation of Porous Materials (Clause 6.2.2)

• Non-rigid/flexible porous materials (felt, mineral wool, quilt):

  • Provide low sound insulation alone.
  • Used in composite partitions with rigid materials for improved insulation per unit weight.

• Porous rigid materials (porous concrete, cinder concrete):

  • Provide about 10% higher sound insulation than non-porous materials of same weight.
  • Recommended to plaster at least one side for best insulation.

2. Sound Insulation vs Weight (Clause 6.2.1 & Table VII)

• For non-porous rigid partitions, sound insulation (Transmission Loss, TL) increases logarithmically with weight per m².
• Doubling weight increases TL by about 4 to 5 dB.
• Table VII provides TL for various weights:

3. Practical Notes

• For porous flexible materials, use them in combination with rigid materials to optimize weight and sound insulation.
• Porous rigid materials should be plastered to maximize insulation.

flowchart LR
    A[Porous Materials] --> B[Flexible (felt, wool)]
    A --> C[Rigid (porous concrete)]
    B --> D[Low sound insulation alone]
    B --> E[Use in composite partitions]
    C --> F[10% higher insulation than non-

IS 1950: Heavy Weight Construction - Key Formulas & Tables

1. Sound Insulation & Weight Relationship (Clause 6.2.1 & Table VII)

• Sound insulation (Transmission Loss, TL) increases logarithmically with wall weight per unit area (kg/m²).
• Doubling the weight increases TL by ~4-5 dB.

2. Thickness for 60 dB Insulation (Clause 6.2.3.1)

• ~100 cm thick solid wall (1,950 kg/m²) or
• ~85 cm thick rock wool (80 kg/m³) needed for 60 dB.
• Double wall with 10 cm air gap is more efficient than single wall of equal weight.

3. Advantages of Porous Materials

• Porous rigid materials (e.g., cinder blocks) reduce vibrations and provide sound absorption due to hollow spaces.

4. Example Sound Reduction Values (Appendix A)

Summary Diagram: Sound Insulation vs Wall Weight

graph LR
  A[Weight 5 kg/m²]

IS 1950 - Sound Insulation: Key Formulas & Table

1. Sound Insulation of Non-Porous Rigid Partitions (Clause 6.2.1)

• Sound insulation increases logarithmically with weight per unit area.
• Doubling the weight per square meter increases sound insulation by ~4 to 5 dB.
• Increasing thickness beyond a point yields diminishing returns.

2. Sound Insulation Values (Table VII)

3. Practical Notes:

• Use well-plastered solid brick masonry or similar dense materials for effective sound insulation.
• For porous materials, refer to Clause 6.2.2 (not detailed here).
• Optimize wall thickness and weight for cost-effective sound insulation.

Formula Approximation:

[ \text{Sound Insulation (dB)} \propto 10 \log_{10}(\text{Weight per unit area}) ]

graph LR
A[Increase Wall Thickness] --> B[Increase Weight per m²]
B --> C[Increase Sound Insulation (dB)]
C --> D[Diminishing Returns Beyond Certain Thickness]

Summary: To improve sound insulation, increase the wall's weight per m², noting that doubling weight adds ~4-5 dB, but excessive thickness is inefficient. Use Table VII for design guidance.

IS 1950: Classification of Partitions (Clause 6.2.6 & related)

Key Table: Classification by Transmission Loss (Table VIII)

Sound Insulation vs Weight (Table VII, Clause 6.2.1)

• Rule of thumb: Doubling wall weight increases sound insulation by ~4-5 dB.
• Example: Two 10 cm brick walls with 10 cm air gap provide ~90 dB insulation (much higher than solid walls).

Notes on Lightweight Partitions (Clause 6.2.3.2)

• Sound mainly transmits through studs, not air gaps.
• Use staggered studs or flexible ties to reduce sound bridging.
• Avoid rigid cross-connections to improve insulation.

flowchart LR
    A[Wall Weight ↑] --> B[Sound Insulation ↑ (~4-5 dB per doubling)]
    C[Single Solid Wall] --> D[Moderate Insulation]
    E[Double Wall + Air Gap] --> F[High Insulation (~+40 dB)]
    G[Stud Partitions] -->

IS 1950: Insulation/Isolation of Impact Sounds - Key Points & Formulas

1. Principle (Clause 6.2.8)

• Impact sound transmission is minimized by interposing resilient materials creating discontinuity in vibration paths.
• Methods:
  • Semi-discontinuous
  • Fully discontinuous

2. Sound Insulation of Floors & Ceilings (Clause 6.2.9)

3. Floating Floor Construction (Concrete Example)

• Typical thickness: 5 cm concrete slab
• Resilient layer: Mineral or glass-wool quilt
• Waterproof paper: Prevents concrete penetration
• Effect: Breaks vibration path, reduces impact sound transmission

flowchart TB
    subgraph Floating Floor
    Concrete[5 cm Concrete Slab]
    Resilient[Mineral/Glass-wool Quilt]
    Waterproof[Waterproof Paper]
    end
    Concrete --> Waterproof --> Resilient

4. Wooden Floors (Clause 6.2.9b2)

• Use mineral/glass-wool quilt isolation between joists
• Add pugging material (sand/ashes) in air space for mass damping
• Minimum 100 kg/m² sand pugging recommended
• Mineral wool density: ≥15 kg/m³ for thin walls (<10 cm)

5. Sound Insulation Values for Rigid Walls (Table VII, Clause 6.2.1)

IS 1950: Sound Insulation of Typical Floors - Key Points

Types of Sound Transmission:

• Air-borne sound: Reduced by heavy, rigid floors (e.g., concrete).
• Structure-borne (impact) sound: Poorly insulated by solid floors; needs special treatment.

Methods for Impact Sound Insulation (Clause 6.2.9):

1. Resilient Surface Materials

   • Materials: Linoleum, cork, carpet, insulation board, asphalt mastic.
   • Improvement: 5 to 10 dB over bare concrete.

2. Floating Floor Construction

   • Concrete floating floor: ~5 cm thick concrete over resilient layer (glass-wool/mineral wool + waterproof paper).
   • Wooden floors: Use mineral/glass-wool quilt between joists; add heavy "pugging" (e.g., sand ≥100 kg/m²) for better damping.

3. Suspended Ceilings with Air Space

   • Use resilient mountings or acoustic clips to isolate ceiling from floor structure.
   • Heavier ceilings + resilient support = highest insulation.

Sound Insulation Values for Floors (Table A-3):

Impact Sound Insulation Requirements (Clause 5.4.2):

• Timber floors in houses/flats: ~20 dB reduction over normal wooden board joist floors.
• Floors above school teaching rooms: Additional ~15 dB over normal timber floor insulation.

Summary Diagram of Floating Concrete Floor Construction:

graph TD
    A[Existing Concrete Floor] --> B[Waterproof Paper]
    B