Recommendations for co-ordination of dimensions in buildings-Arrangement of building components and assemblies, Part 2: Functional group 2 External envelope
1974 الطبعة

IS 7564 Part 2 specifies key coordinating measurements for external walls and openings within Functional Group 2 - External Envelope. For walls like brickwork and blockwork, length, height, and thickness are essential dimensions to coordinate. Damp proof courses require coordination of width and thickness, while lintels need length, width, and thickness alignment. Wall openings such as door and window frames, door leaves, and ventilators emphasize width, height, and thickness coordination. These standards promote modular compatibility and ensure functional integration of all external components.

The standard categorizes components into three grades to prioritize dimensional coordination: Grade A where coordination is critical, Grade B where it is necessary in specific cases, and Grade C where coordination is not required. This system helps focus attention on key external envelope elements like main walls and primary openings, ensuring they conform to strict dimensional controls for seamless assembly and performance.

Components demanding strict dimensional coordination (Grade A) include major structural walls (brickwork, blockwork), lintels, facing materials, curtain wall elements, glazing units, door frames and leaves, window frames, sills, ventilators, and roller shutters. These parts are critical to the building’s envelope integrity and must adhere closely to prescribed dimensions to ensure proper fit and functional assembly.

IS 7564 Part 2 integrates with other functional groups by defining dimension coordination for the external envelope in relation to structural, finishing, drainage, and service groups. It promotes correlation of component sizes only when functional interaction exists, referencing international standards to maintain global compatibility. This approach enables coherent modular sizing and seamless interface between building elements across different disciplines.

The standard specifies joint clearances and tolerances as part of the coordinating space to accommodate manufacturing and installation variations. Typical joint clearances range from ±1 mm to ±3 mm depending on the component type, such as window frames, door leaves, glazing units, and curtain wall mullions. These allowances ensure proper assembly fit, accommodate thermal expansion, and maintain weather tightness, thus supporting the durability and functionality of the building envelope.