Recommendations for modular co-ordination: notations and symbols for modular drawings

IS 11775: Scope - Key Specifications & Units

The scope of IS 11775 primarily deals with modular coordination in building construction, focusing on standardized grid lines and dimensions for modular drawings.

Key Points from Clause 2.22.2 (Modular Grid Lines)

• Grid line intervals are differentiated by line types:
  • Thin line: smallest interval
  • Thick line: next larger interval
  • Chain line: modular line in axial position

International System of Units (SI) Used

Modular Coordination Notes

• The standard aligns with international practices and Indian field conditions.
• It references modular coordination notations and symbols for modular drawings to ensure uniformity.

flowchart LR
    A[Modular Grid Lines] --> B[Thin line: Smallest interval]
    A --> C[Thick line: Next larger interval]
    A --> D[Chain line: Axial modular line]

This ensures clarity and uniformity in architectural and structural drawings per IS 11775.

IS 11775: Modular Lines - Key Points

1. Modular Lines (Clause 2.1)

• Modular lines are reference grid lines used for systematic layout and planning of structures.
• They define the primary framework for positioning structural elements.

2. Modular Lines Planning (Clause 2.2)

• Planning involves spacing modular lines at regular intervals to optimize material use and structural efficiency.
• Typical modular spacing: 3m to 6m depending on structural requirements.

3. Identification on Modular/Reference Lines (Clause 2.20)

• Modular lines are identified by alphabets (A, B, C...) in one direction and numbers (1, 2, 3...) in the perpendicular direction.
• This grid system aids clear location referencing of elements.

4. Modular Dimensions (Clause 2.12)

• Modular dimensions are standardized increments, generally multiples of 300 mm (0.3 m).
• Common modular dimension formula:

[ \text{Modular Dimension} = n \times 300 \text{ mm} \quad (n = 1,2,3,...) ]

Summary Table: Modular Dimensions

graph TD
    A[Modular Lines] --> B[Planning: Regular Spacing]
    B --> C[Spacing: 3m to 6m]
    A --> D[Identification]
    D --> E[Alphabets (A,B,C...)]
    D --> F[Numbers (1,2,3...)]
    A --> G[Dimensions]
    G --> H[Multiples of 300 mm]

This modular grid system ensures uniformity, ease of construction, and efficient material usage.

IS 11775 - Centre Lines (Clause 2.7)

• Definition: Centre lines represent the exact axes of walls, columns, beams, etc., on drawings.
• Drawing Representation:
  • Use thin stippled lines (dashed lines).
  • Mark centre lines clearly at each end with a centre line symbol (cross or tick marks).
  • Refer to Fig. 7 in IS 11775 for graphical illustration.

Related Clauses:

• 2.4 Reference Lines: Establish baseline or datum lines for measurements.
• 2.5 Location of Reference Lines: Specifies how reference lines are positioned relative to the structure.

Practical Tips:

• Centre lines are used for accurate positioning during construction.
• They serve as control lines for layout and dimensioning.
• Always maintain consistent line thickness and marking style for clarity.

Visual Example (simplified):

flowchart LR
A[Wall] ---|Centre line| B((--- - - - - ---))
B --> C[Centre line marking]

For detailed dimensions and graphical symbols, always refer to Fig. 7 of IS 11775.

IS 11775 - Dimension Line Terminations (Clause 2.9)

• Arrowhead Shape & Angle (2.9.1):

  • Arrowheads are short lines forming barbs at an included angle between 15° and 90°.
  • Types: Open, Closed, or Closed & Filled (See Fig. 9).

• Arrowhead Placement (2.9.3):

  • Preferably within the dimension line limits if space allows.
  • If space is limited, arrowheads may be placed outside the dimension line, which is extended accordingly.

• Dimension Figures (2.10.2):

  • Figures (numerical values) are placed on the running dimension line near the arrowhead (See Fig. 10).

Summary Table for Arrowhead Specifications

flowchart LR
    A[Dimension Line] --> B[Arrowhead Termination]
    B --> C{Space Available?}
    C -->|Yes| D[Arrowhead within dimension line]
    C -->|No| E[Extend line & place arrowhead outside]
    D & E --> F[Figures placed on dimension line near arrowhead]

This ensures clarity and uniformity in technical drawings per IS 11775.

IS 11775: Modular Space & Dimensions - Key Points

1. Modular Space (Clause 2.3)

• Defines the basic unit of space used for modular coordination.
• Typically based on a module size of 100 mm or 300 mm.
• Modular space ensures interchangeability and standardization in building components.

2. Modular Dimensions (Clause 2.12)

• Dimensions are multiples of the basic module.

• Common modular dimensions:

  Dimension Type	Value (mm)
  Basic Module (M)	100 or 300
  Half Module	50 or 150
  Double Module	200 or 600

• Modular dimensions simplify design, fabrication, and installation.

3. Recommendations for Modular Coordination: Notations & Symbols

• Use M to denote module size (e.g., 3M = 300 mm if M=100 mm).
• Symbols indicate modular increments in drawings for clarity.
• Example:
  • M = module
  • nM = n times module (e.g., 5M = 500 mm if M=100 mm)

Summary Table

flowchart LR
    A[Basic Module (M)] --> B[Half Module (0.5M)]
    A --> C[Double Module (2M)]
    B --> D[Used for fine adjustments]
    C --> E[Used for larger components]

Use modular coordination to enhance design efficiency, reduce waste, and standardize construction.

IS 11775 - Facade Corners of Wall Surfaces (Clause 2.8)

• Symbolization on Drawings (Clause 2.8.1):

  • Facade corners at external envelopes are shown as thin stippled or continuous lines with squares at both ends.
  • Squares indicate the reference system for the building.
  • (Refer Fig. 8 in IS 11775 for graphical representation).

• Axial Planning (Clause 2.7.2):

  • If facade corners fall on axial planning lines, they are marked with circles at ends along with the central line.
  • Circles also indicate the building's reference system.

• Reference Line Identification (Clause 2.20.1):

  • Building elements are positioned on a grid with alphabetic labels on X-axis (horizontal) and numerical labels on Z-axis (vertical).
  • Example:
    • D1 = Circular column at intersection of line D and 1
    • C2-D2 = Beam span between columns C2 and D2 on line 2
    • C1-C2 = Beam span between columns C1 and C2 on line C

Summary Table for Facade Corner Symbols

Visualization (Simplified schematic):

graph LR
  A[Facade Corner] -->|Thin stippled line| B[Square Ends]
  C[Axial Planning] -->|Central line| D[Circle Ends]
  E[Grid] --> F[X-axis: Alphabetic]
  E --> G[Z-axis: Numeric]

Note: IS 11775 focuses on graphical representation and reference system for facade corners rather than structural formulas. For structural design, refer to relevant codes like IS 456 or IS 875.

IS 11775: Neutral Zones (Modular & Non-Modular)

1. Neutral Zones - Definitions

• Modular Neutral Zone (Clause 2.15):
  Neutral zones in modular construction are represented by thin stippled lines with a circle at the end (Fig. 15).

• Non-Modular Neutral Zone (Clause 2.16):
  Neutral zones in non-modular construction are shown by thin stippled lines with half circles at the ends (Fig. 16).

2. Key Specifications

3. Usage Notes

• Neutral zones indicate transition or interface areas where modular or non-modular elements meet.
• These zones help in layout clarity and structural detailing.

4. Visualization (Simplified)

flowchart LR
    A[Neutral Zone] -->|Modular| B((Circle ends))
    A -->|Non-Modular| C(half-circle ends)

For detailed dimensions or formulas, refer to the specific figures (Fig. 15 & 16) in IS 11775, which graphically define the neutral zone extents.

IS 11775: Modular Dimensions Overview

Clause 2.12: Modular Dimensions

• Modular dimensions are standardized sizes based on a fixed module (M).
• Dimensions are expressed as multiples of M:
  [ \text{Dimension} = n \times M ] where ( n ) is an integer.
• This ensures interchangeability and ease of manufacturing.

Clause 2.21: Combination of Dimensions

• Working dimensions = Modular dimensions + allowances/tolerances.
• Checking dimensions verify the manufactured part against modular and working dimensions.
• The combination ensures functional fit and manufacturability.

Clause 2.13: Non-Modular Dimensions

• Dimensions not conforming to multiples of the module.
• Used when exact modular sizes are impractical.

Clause 2.14: Manufacturing Dimensions (Non-Modular)

• Actual sizes used in production.
• Include allowances for machining, wear, and assembly.

Typical Modular Dimension Table (Example)

Summary:

• Use modular dimensions for standardization.
• Combine with working/checking dimensions for quality control.
• Use non-modular dimensions only if necessary for manufacturing.

flowchart LR
    A[Modular Dimension (n × M)] --> B[Working Dimension (Modular + Allowance)]
    B --> C[Manufacturing Dimension (Non-Modular)]
    C --> D[Checking Dimension (Verification)]

IS 11775: Non-Modular Dimensions (Clause 2.13)

• Non-Modular Dimensions are those not based on the standard modular unit (usually 100 mm or 50 mm increments).
• These dimensions allow flexibility for custom sizes beyond the modular grid.
• Typically used where exact fit or architectural aesthetics override modular constraints.

Key Points from Clauses:

Typical Use:

• Non-modular sizes = Modular size ± tolerance or custom dimension.
• Used for working dimensions (actual site measurements) and checking dimensions (inspection).

Example Table: Modular vs Non-Modular Dimensions

Summary:

• Use modular dimensions for standardization.
• Use non-modular dimensions for exact fitting or architectural requirements.
• Always refer to Clause 2.21 for combining dimensions in design and quality checks.

flowchart LR
    A[Design Dimensions] --> B[Modular Dimensions (2.12)]
    A --> C[Non-Modular Dimensions (2.13)]
    C --> D[Manufacturing Dimensions (2.14)]
    B & D --> E[Combination & Checking (2.21)]

IS 11775: Key Points on Checking Dimensions

1. Clause 2.11 - Checking Dimensions

• Checking dimensions control essential sizes (clear widths, heights).
• Shown as continuous thin lines with small oblique strokes clockwise.
• Represent clear width in plan and heights in vertical sections.
• Refer to Fig. 11 for graphical representation.

2. Clause 2.21 - Combination of Dimensions

• Modular, working, and checking dimensions can coexist on drawings.
• Used to relate working dimensions to modular sizes and verify correctness.
• Symbols for each dimension type are distinct (refer Fig. 21).

3. Dimensioning Practice Summary:

4. General Tips:

• Always indicate checking dimensions clearly for quality control.
• Use combined dimensioning to avoid errors and ensure modular coordination.

flowchart LR
    A[Modular Dimension] --> B[Working Dimension]
    B --> C[Checking Dimension]
    C --> D[Verification of Clearances]

This ensures clarity in drawings and helps maintain dimensional accuracy during construction.

IS 11775 - Order of Erection: Key Points

• Clause 2.18.2:

  • Numerical values inside squares indicate the sequence of erection steps.
  • This ensures a clear, unambiguous erection order for structural elements (see Fig. 18).

• Clause 2.20.1:

  • Positioning of elements (walls, columns, beams) uses a reference grid system:
    • Horizontal (X-axis): Alphabetic labels (A, B, C, ...)
    • Vertical (Z-axis): Numerical labels (1, 2, 3, ...)
  • Example:
    • D1 = Circular column at intersection of line D and No. 1
    • C2-D2 = Beam between columns C and D on line 2
    • C1-C2 = Beam between columns C1 and C2 on line C

Summary Table: Reference Line Identification

Practical Use:

• Mark erection sequence numerically on drawings.
• Use grid references for precise element location.
• Follow the numbered sequence to maintain structural stability during construction.

graph TD
  A[Start Erection] --> B[Element 1: Square with "1"]
  B --> C[Element 2: Square with "2"]
  C --> D[Element 3: Square with "3"]
  D --> E[Complete Structure]

This systematic approach ensures safe and efficient construction following IS 11775 guidelines.

IS 11775: Identification on Modular/Reference Lines

Key Clauses:

• 2.1 Modular Lines:
  Defines modular lines as reference lines spaced at regular intervals (usually 100 mm or multiples) to coordinate dimensions in building design.

• 2.20 Identification on Modular/Reference Lines:
  Specifies marking and labeling of these lines on drawings for clarity and uniformity.

Key Specifications:

• Modular Grid Spacing:
  Typically 100 mm or multiples (e.g., 300 mm, 600 mm) to maintain dimensional consistency.

• Identification:

  • Lines are numbered or lettered sequentially (e.g., 1, 2, 3 or A, B, C).
  • Use bold continuous lines for primary modular lines.
  • Secondary or sub-modular lines may be dashed or thinner.

• Notation Symbols:

Example Table: Modular Line Identification

graph LR
A[Primary Modular Line (600mm)] --> B[Secondary Modular Line (100mm)]
B --> C[Sub-Secondary Lines (50mm)]

Summary: Use modular lines spaced at standard intervals (100 mm multiples), clearly labeled with numbers/letters, and distinct line styles for easy identification on drawings per IS 11775.

IS 11775 - Section Markings: Key Specifications

• Line Types & Symbols:

  • Clause 2.6.1: Section lines are thin stippled or continuous lines with a circle inside a diamond at each end (see Fig. 6).
  • Clause 2.4.1: Similar lines but marked with a diamond only at each end (see Fig. 4).

• Modular Grid Lines (Clause 2.22.2):

  • Smallest interval: thin line
  • Next larger interval: thick line
  • Axial modular line: chain line
  • Ends marked with diamonds (see Fig. 22).

Summary Table of Line Types for Section Markings

Units Reference (SI Units from IS 11775)

flowchart LR
    A[Section Lines] --> B[Thin stippled/continuous]
    B --> C{End Marking}
    C -->|Circle inside diamond| D[Clause 2.6.1]
    C -->|Diamond only| E[Clause 2.4.1]

    F[Modular Grid Lines] --> G[Line Thickness]
    G --> H[Thin line

IS 11775 - Combination of Modular, Working, and Checking Dimensions (Clause 2.21)

• Purpose: To clearly represent working dimensions relative to modular sizes and verify correctness using checking dimensions.

Key Points:

1. Modular Dimensions (Clause 2.12):

   • Standardized base dimensions (modules) used as reference units.
   • Represented with a specific symbol (e.g., M).

2. Working Dimensions:

   • Actual dimensions required for construction or fabrication.
   • Derived from modular dimensions, adjusted for site conditions.

3. Checking Dimensions (Clause 2.11):

   • Used to verify correctness of working dimensions.
   • Ensure that the sum of parts matches the overall modular dimension.

Combination (Clause 2.21.1):

• Symbols for Modular (M), Working (W), and Checking (C) dimensions are shown together in drawings.
• This helps in cross-verifying dimensions and maintaining modular coordination.

Typical Dimensioning Format Example:

Visual Concept (Fig. 21):

graph LR
    M[Modular Dimension (M)] --> W[Working Dimension (W)]
    W --> C[Checking Dimension (C)]
    C --> M

• Interpretation: Working dimensions are derived from modular sizes and verified by checking dimensions to ensure accuracy.

Reference: Use this combination to maintain modular coordination and dimensional accuracy in structural drawings per IS 11775.

IS 11775: Symbols and Notations Summary for Modular Coordination

IS 11775 standardizes notations and symbols used in modular drawings to ensure uniformity in construction documentation.

Key Points:

• Purpose: Facilitate clear communication in modular coordination by using standardized symbols.
• Scope: Covers graphical symbols for doors, windows, partitions, fixtures, and modular elements.
• Notation system: Uses alphanumeric codes combined with graphical symbols to represent components.

Typical Symbols Include:

Modular Dimensions:

• Based on a modular grid, typically in multiples of 100 mm or 300 mm.
• Ensures components fit within the modular framework.

Summary Table for Notations:

For detailed graphical symbols and exact modular dimensions, refer to IS 11775 diagrams.

graph TD
A[Modular Drawing] --> B[Doors (D1, D2)]
A --> C[Windows (W1, W2)]
A --> D[Partitions (P1, P2)]
A --> E[Fixtures (F1, F2)]

Note: Always cross-check with IS 11775 for exact symbol shapes and modular sizing conventions.