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IS 4993:1983 is the Indian Standard (BIS) for glossary of terms relating to modular coordination. This standard provides a comprehensive glossary of terms related to modular coordination in the building industry. It establishes the fundamental principles and definitions, such as the basic module (100 mm), multimodules, and various types of grids and dimensions. The goal is to promote standardization of building components for easier design, manufacturing, and assembly.
Glossary of terms relating to modular coordination
Overview
Status
Current
Usage level
Specialized
Domain
Architectural — Planning, Housing and Pre-fabricated Construction
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! The fundamental principle of this code is the use of a basic module 'M' which is internationally and nationally accepted as 100 mm.
! This code is the theoretical foundation for all design and manufacturing based on prefabrication and system building in India.
! Though an old code (reaffirmed 2018), its principles are highly relevant for modern methods like BIM, off-site manufacturing, and DfMA (Design for Manufacturing and Assembly).
ISO 6707-1:2020ISO (International Organization for Standardization), International
HighCurrent
Buildings and civil engineering works — Vocabulary — Part 1: General terms
A comprehensive vocabulary standard that includes and supersedes older, specific modular coordination terminology standards.
ISO 1006:2003ISO (International Organization for Standardization), International
HighCurrent
Building construction — Modular coordination — Basic module
Defines the basic module (M), which is the fundamental unit of measure in IS 4993.
BS EN ISO 6707-1:2017BSI (British Standards Institution), United Kingdom
HighCurrent
Buildings and civil engineering works. Vocabulary. General terms
The British and European adoption of the core ISO vocabulary standard, demonstrating harmonized terminology.
ISO 1791:1983ISO (International Organization for Standardization), International
HighWithdrawn
Building construction — Modular coordination — Vocabulary
The direct contemporary international equivalent to IS 4993:1983, now withdrawn and integrated into broader standards.
Key Differences
≠IS 4993:1983 is a standalone, dedicated glossary for modular coordination, whereas modern international practice consolidates this terminology within a much broader vocabulary standard, ISO 6707-1, which covers all of building and civil engineering.
≠The Indian standard from 1983 does not account for modern digital design processes like Building Information Modeling (BIM), while the context and application of current ISO standards are heavily influenced by digital data exchange and management.
≠IS 4993 is more prescriptive in its recommendation of preferred multimodules (e.g., 3M, 6M, 12M, 15M, 30M, 60M for horizontal dimensions), while the ISO series focuses more on establishing the principles of modularity, leaving specific preferred sizes more flexible.
Key Similarities
≈The fundamental concept and value of the basic module 'M' is identical, defined as 100 mm in both IS 4993 and the cornerstone international standard ISO 1006.
≈Both the Indian and international standards are built upon the same core principles of using grid systems (planning grid, structural grid, etc.) to define spaces and locate components in a coordinated manner.
≈The hierarchical sizing concept is consistent: a 'Coordinating Size' (space for the component) is larger than the 'Work Size' (manufacturing size) to allow for joints and tolerances.
≈The use of 'multimodules' (integer multiples of the basic module M) for defining the sizes of larger components and planning grids is a shared fundamental principle.
Parameter Comparison
Parameter
IS Value
International
Source
Basic Module (M)
100 mm
100 mm
ISO 1006:2003
Scope of Terminology
Dedicated to modular coordination only.
Integrated into a general vocabulary for all building and civil engineering works.
ISO 6707-1:2020
Definition of 'Coordinating Size'
A size of a coordinating space allocated to a component, including allowances for joints and tolerances.
Size of a coordinating space intended for a component, including allowances for joints and dimensional deviations.
ISO 6707-1:2020
Definition of 'Work Size'
A size specified for the manufacture of a building component...
Size of a building component specified for its manufacture...
ISO 6707-1:2020
Preferred Horizontal Multimodules
Prescribes a specific set (3M, 6M, 12M, 15M, 30M, 60M).
No prescribed list; recommends the principle of using integer multiples of M.
General principle of ISO modular series
Concept of 'Neutral Zone'
The space between the modular grid lines and the corresponding faces of components. It is not specifically defined as a primary term.
Term 'Neutral Zone' is defined as a space between two parallel modular planes, in which a component can be placed.
ISO 6707-1:2020
⚠ Verify details from original standards before use
What is the value of the basic module 'M' in India?+
The basic module 'M' is defined as 100 mm (Clause 2.4).
What is Modular Coordination (MC)?+
It is a dimensional coordination system based on the basic module 'M', used to dimension building components and the building itself to reduce complexity and improve interoperability (Clause 2.15).
What is a multimodule?+
A multimodule is a standardized larger unit which is a direct multiple of the basic module (e.g., 3M = 300 mm). They are used for coordinating larger components and spaces (Clause 2.21).
Why is this code important for BIM?+
The principles of modular grids and standardized component dimensions defined here are core to creating efficient, clash-free, and manufacturable BIM models.