Pre-manufacturing (3D primary structural systems)
Modern Methods of Construction, Introducing the MMC definition framework, published by Ministry of Housing, Communities & Local Government (MHCLG) in 2019 defines 7 categories for MMC:
- Category 1 – Pre-manufacturing (3D primary structural systems).
- Category 2 – Pre-manufacturing (2D primary structural systems).
- Category 3 – Pre-manufacturing components (non-systemised primary structure).
- Category 4 – Additive manufacturing (structural and non-structural)
- Category 5 – Pre-manufacturing (non structural assemblies and sub-assemblies).
- Category 6 – Traditional building product led site labour reduction / productivity improvements.
- Category 7 – Site process led site labour reduction / productivity / assurance improvements.
Category 1 – Pre-Manufacturing (3D primary structural systems) is defined as:
‘A systematised approach based on volumetric construction involving the production of three-dimensional units in controlled factory conditions prior to final installation. Volumetric units can be brought to the final site in a variety of forms ranging from a basic structure only to one with all internal and external finishes and services installed, all ready for installation.
The system includes structural performance. Full volumetric units in apartment buildings can include apartment space and common area space. Mini volumetric structural units can include bathroom pods and the like which are structurally stacked and loaded.’
[edit] Related articles on Designing Buildings Wiki
- British post-war mass housing.
- Design for deconstruction.
- Design for Manufacture and Assembly (DfMA).
- MMC definition framework.
- Modern methods of construction.
- Off site, on track.
- Off-site construction.
- Off-site prefabrication of buildings: A guide to connection choices.
- Prefabrication.
- Pre-manufactured value
- Volumetric.
Featured articles and news
We're expanding our collaborative mission by launching DB Intelligence, an exclusive market research advisory panel. Built environment professionals can now get paid to share their expertise on industry trends, products and services.
Panel members receive direct financial incentives for participating in research projects like short surveys, 1-2-1 interviews and focus groups. Register today to shape the future of the construction sector.
Building Control Independent Panel final report
A precis of a key report led by Dame Hackitt with full recommendations and link to the government response.
Guide to ISO 19650 for Architecture Firms (2026)
A user gives their low down.
A UK training and membership provider for mould remediation professionals.
Building Safety recap April, 2026
A short and longer run-through of the month, with links to further information and sources.
CIAT May 2026 briefing.
Independent NSI and BAFE study exploring how organisations are changing the way they buy fire safety services.
From medieval scribes to modern word art.
ECA welcomes crackdown on late payment and push for clean energy, whilst CIOB seek fixed cladding removal timeframes.
Cyber Security in the Built Environment
Protecting projects, data, and digital assets: A CIOB Academy TIS.
Managing competence in the built environment
ITFG publishes new industry guide on how to meet the ICC principles.
The UK's campaign to reduce noise pollution: Mythbusting, articles and topic guides.

















