Modular co-ordination for normal brickwork - Recommendations, Part 1: Burnt clay bricks
1993 Edition

Overview of IS 13612 Part 1: Scope and Key Specifications

1. Horizontal Coordination Module (Clause 6.3.2)

• Horizontal controlling dimension defined as 3M = 5 × 60 mm = 300 mm for non-modular bricks.
• Nominal sizes of bricks (mm):

2. Brick Dimension Tolerances (Clause 7.3)

• For partial bricks (1/4, 1/2, 3/4), a total of 10 mm is deducted to accommodate joint thickness.

3. Principles of Modular Coordination (Clauses 5.1 & 11.4)

• Horizontal dimensions follow multiples of 3M (M = 100 mm for modular bricks).
• Vertical dimensions use multiples of 2M.
• Actual opening sizes are calculated as modular dimension plus 10 mm.
• Wall dimensions are modular dimension minus 10 mm.

4. Wall Thickness Guidelines (Figures 8A & 8B)

• Thickness for modular brick walls: 1 brick = 100 mm, 1.5 bricks = 150 mm, etc.
• Thickness for non-modular brick walls: 1 brick = 80 mm, 1.5 bricks = 120 mm, etc.

Summary Table: Brick Sizes and Tolerances

IS 13612 Part 1: Fundamental Concepts - Important Specifications and Tables

1. Key Controlling Dimensions (Clause 6.3.2)

• Horizontal controlling length specified as 3M = 5 × 60 mm = 300 mm.
• Typical nominal and actual dimensions (in mm):

2. Brick Tolerances (Clause 7.3)

• A 5 mm allowance is subtracted from each face for mortar joints.
• Example for non-modular bricks:

3. Wall Horizontal Dimensions (Clause 11.4)

• Opening sizes = modular dimension + 10 mm.
• Wall lengths = modular dimension - 10 mm.

4. Wall Thickness Examples

• Modular bricks: single brick thickness is 190 mm.
• Non-modular bricks: single brick thickness is 230 mm.

Table: Non-Modular Brick Size Examples (Clause 10.3.2)

IS 13612 Part 1: Application Scope - Essential Specifications and Tables

1. Modular Coordination Fundamentals (Clause 5.1)

• Horizontal dimensions adopt multiples of 3M.
• Vertical dimensions adopt multiples of 2M.
• Referenced standards include IS 6820:1987, IS 7921:1987, IS 7922:1987.

2. Controlling Brick Dimensions (Clause 6.3.2)

• Horizontal controlling dimension for non-modular bricks is 3M = 5 × 60 mm = 300 mm.

3. Brick Tolerances (Clause 7.3)

• Each brick face has a 5 mm joint allowance deducted for length, width, height, and cut bricks.

4. Coordination of Openings and Wall Dimensions (Clause 11.4)

• Openings = modular dimension + 10 mm.
• Wall dimensions = modular dimension - 10 mm.

5. Wall Thickness Examples

• Thickness for walls of one and a half bricks varies by brick type (see Figures 8A & 8B).

Summary Table: Horizontal Coordination

Essential Specifications and Tables for Modular Brickwork (IS 13612 Part 1)

1. Core Coordinating Dimension (Clause 9.1.1)

• Vertical plane dimension for modular bricks is calculated by:

  [ \text{Dimension} = n \times 50; \text{mm} - \text{joint thickness (typically 10 mm)} ]

• Here, n represents the count of modular increments.

2. Modular Brick Sizes and Actual Dimensions (After 5 mm Deduction per Joint)

*Used as quoin closer or half header.

3. Coordination Dimensions for Modular Bricks

Brick Dimensional Tolerances per IS 13612 Part 1 (Clause 7.3)

• General Rule: Every brick dimension (length, height, width, including cut pieces like closers and bats) is reduced by 5 mm on each face to accommodate mortar joint thickness.

1. Modular Brick Tolerances (50 mm Module)

2. Non-Modular Brick Tolerances (60 mm Module)

Notes:

• The 10 mm total reduction corresponds to two mortar joints of 5 mm thickness each on opposite faces.
• These tolerances maintain dimensional accuracy and ensure proper bonding.
• Refer to IS 6408 (Part 2):1990 for detailed tolerance applications.

flowchart LR
    A[Nominal Brick Length] --> B[Subtract 5 mm per side]
    B --> C[Final Brick Length for Bonding]
    C --> D[Ensures Correct Mortar Joint Thickness]

Summary: Always apply the 5 mm deduction per face to maintain modular consistency.

Horizontal Dimensioning of Walls per IS 13612 Part 1

Relevant Clauses:

• Clauses 8.3 & 8.4: Horizontal dimensions must control wall length using the '5-mm Rule' for specifying wall and opening sizes.
• Clauses 6.2 & 6.4: Preferred horizontal dimensions are based on brick controlling sizes.

The '5-mm Rule' (as per IS 7921:1987):

• Horizontal wall and opening dimensions should be multiples of the brick unit plus mortar thickness, allowing a ±5 mm tolerance.
• This practice minimizes on-site cutting and ensures dimensional precision.

Typical Horizontal Dimensioning Approach:

• Use modular dimensions derived from brick size (e.g., 190 mm length plus 10 mm mortar = 200 mm module).
• Wall length = (number of bricks × (brick length + mortar thickness)) ± 5 mm.

Summary:

• Wall horizontal lengths are calculated as n × 200 mm ± 5 mm, where n is an integer number of bricks.
• This modular system simplifies construction and ensures compatibility with openings and other structural elements.

flowchart LR
    A[Select Wall Length] --> B[Calculate n = Wall Length / 200]
    B --> C{Is n Integer?}
    C -- Yes --> D[Wall Length = n × 200 ± 5 mm]
    C -- No --> E[Adjust Wall Length to Nearest Multiple]
    E --> D

This method guarantees dimensional control, reducing waste and rework.

Vertical Dimensioning of Walls According to IS 13612 Part 1

Key Clause Highlights:

• Clause 9.4: The 5-mm Rule is applied to vertical wall and opening dimensions (per IS 7922:1987).
• Clause 9.3: Recommended vertical dimensions control heights of sills, lintels, rooms, and floors.
• Clause 6.2: Brick controlling dimensions must be adhered to.

The 5-mm Rule (IS 7922:1987)

• Vertical measurements for walls and openings should be multiples of 5 mm.
• This supports modular coordination and minimizes cutting waste.

Recommended Vertical Dimensions (Typical Values)

Summary:

• Vertical dimensions should be multiples of 5 mm.
• Select dimensions as multiples of brick course height (75 mm).
• Control sill, lintel, and floor heights to maintain modular compatibility.

flowchart TD
    A[Begin: Vertical Dimension] --> B{Apply 5-mm Rule?}
    B -- Yes --> C[Dimension = Multiple of 5 mm]
    C --> D{Matches Brick Course?}
    D -- Yes --> E[Dimension = Multiple of 75 mm]
    D -- No --> F[Adjust to Nearest Multiple]
    E --> G[Set Sill, Lintel, Floor Heights]
    F --> G
    G --> H[Final Vertical Dimension]

This facilitates precision, modularity, and ease in construction.

Wall Thickness According to IS 13612 Part 1 (Clauses 10 & 7.3):

Wall thickness is influenced by brick size and bonding patterns, factoring the '5-mm Rule' for joint allowances.

Specifications:

• Modular Bricks (Nominal size 190 × 90 × 90 mm)

• Non-Modular Bricks (Nominal size 230 × 110 × 75 mm)

Notes:

• The 5-mm Rule entails deducting 5 mm on each brick surface to account for mortar joints.
• Thickness typically corresponds to multiples of brick width (50 mm for modular, 60 mm for non-modular).
• Brick-on-edge courses may be employed for non-modular bricks or specific functional needs (Clause 9.5).

Wall Thickness Formula:

[ \text{Wall Thickness} = n \times (\text{Brick Width}) - 10 \text{ mm} ]

where ( n ) is the number of brick widths (e.g., 1/4, 1/2, 3/4, 1 brick).

graph LR
A[Brick Width] --> B[Calculate n × Brick Width]
B --> C[Subtract 10 mm for joints]
C --> D[Final Wall Thickness]

Key Principles of Coordinate Dimensioning in IS 13612 Part 1

1. Planning Modules (Clause 5.1)

• Horizontal dimensions are based on multiples of 3M.
• Vertical dimensions use multiples of 2M.
• Refer to IS 6820:1987, IS 7921:1987, IS 7922:1987 for modular coordination standards.

2. Non-Modular Brick Sizes (Clause 10.3.2)

3. Horizontal Controlling Dimensions (Clause 6.3.2)

• The horizontal controlling dimension 3M = 5 × 60 mm = 300 mm for non-modular bricks.

4. Controlling Dimension Concept

• Horizontal alignment uses multiples of 3M (180 mm nominal) to regulate brickwork layout.
• This approach ensures modular coordination and consistent bonding patterns such as English or Flemish bond.

flowchart LR
    A[Planning Module] --> B[Horizontal Dimensions: Multiples of 3M]
    A --> C[Vertical Dimensions: Multiples of 2M]
    B --> D[Align Brick Lengths]
    C --> E[Align Brick Heights]
    D & E --> F[Ensure Uniform Bonding]

Key Considerations for Wall Placement in IS 13612 Part 1

1. Application of the 5-mm Rule (Clauses 8.4 & 9.4)

• Deduct 5 mm from all horizontal and vertical wall and opening dimensions.
• This accounts for mortar joints and assures correct modular sizing.
• Refer IS 7921:1987 for horizontal and IS 7922:1987 for vertical application details.

2. Modular Lines for Openings (Clause 11.3)

• Doors and windows must be positioned along the center lines of brick joints (modular lines).
• This practice ensures structural consistency and wall uniformity.

3. Brick Tolerances (Clause 7.3)

• Brick dimensions are reduced by 5 mm per joint for modular wall measurements.

4. Wall Dimension Calculation (Horizontal/Vertical)

[ \text{Effective Wall Length} = n \times (\text{Brick Length} - 5, \text{mm}) ]

where n denotes the number of bricks along length or height.

flowchart LR
    A[Start: Wall Layout] --> B[Apply 5-mm Deduction]
    B --> C[Compute Effective Brick Size]
    C --> D[Position Openings on Modular Lines]
    D --> E[Build Wall with Specified Tolerances]

Summary: Employ the 5-mm deduction per joint to achieve precise wall and opening dimensions, aligning openings on brick joint lines.

IS 13612 (Part 1): 1993 — Referenced Indian Standards

This segment of IS 13612 cites essential standards supporting modular coordination in burnt clay brick masonry.

List of Key Referenced IS Codes

Important Notes:

• Actual openings are 10 mm greater, and wall dimensions are 10 mm less than modular dimensions (Clause 11.4).
• Modular bricks are preferred for better dimensional control.
• IS 1077 and IS 2180 define modular brick sizes such as 200×100×100 mm.

Coordination Concept Diagram:

flowchart LR
    A[Modular Dimension] -->|+10 mm| B[Actual Opening Size]
    A -->|-10 mm| C[Wall Dimension]

This framework ensures accurate fitting and dimensional harmony in brick masonry construction.

For comprehensive tables and tolerances, consult the listed IS standards.