A module is the fixed basic dimension a building is set out in: every main dimension is a multiple of it. Internationally the basic module is defined in ISO 1006 as 1 M = 100 mm. ISO 2848 develops that modular coordination further, with preferred sizes in multiples of 3 M (300 mm) and 6 M (600 mm).
In construction the word carries a second, broader meaning as well: a module is also a complete, factory-made building element — a bathroom pod, a façade module or a volumetric unit in modular construction.
Why modular sizes exist
Without an agreement about dimensions, nothing fits. Because everything is based on the same unit, manufacturers can supply products that go together without filler pieces. Familiar consequences:
- Sheet materials in 1200 × 2400 mm and 1200 × 3000 mm
- Centres of 300, 400 and 600 mm for studs, purlins and joists
- Windows and kitchen units in steps of 100 or 50 mm
- Suspended ceiling grids of 600 × 600 mm
Application
- Design on the grid. Choose your main dimensions (bay width, storey height, façade panel) in multiples of 100 mm. That saves a great deal of cutting and fitting on site
- Coordinating size versus work size. The modular size is the calculation size including the joint. A brick 215 mm long with a 10 mm joint has a coordinating size of 225 mm; always calculate with the size including the joint
- Sheathing. Match the stud centres to the board width so every board edge lands on a stud: with 1200 mm boards, work at 400 or 600 mm centres
- Modular construction. With volumetric units the size is often set by what can be transported by road. Abnormal loads need separate permits, so agree the width with the manufacturer early
- Refurbishment. In existing buildings the grid rarely holds. Measure every opening individually rather than assuming a nominal modular size
Related terms
- Dimensional coordination
- Prefabrication
- Window
- Brick
- Modular construction
Want to learn more about construction terms? Visit our knowledge base at fredsdiyplans.com.