Design for Manufacture and Assembly with Design for Reuse
This report examines the application of Modern Methods of Construction (MMC) in Ireland, how this can be enabled through Design for Manufacture and Assembly (DfMA) and its relationship with Design for Reuse (DfR). MMCs offer significant potential productivity, sustainability and quality benefits in the delivery of new housing projects by employing off-site manufacturing methods, including modular construction and structural panels. However, the use of MMC can be restricted by wide-ranging challenges related to the co-ordination of project stages, stakeholder collaboration and operational requirements. Capturing the full cost and productivity benefits of MMC involves selecting the right solution between 2D panels, 3D modules, and hybrid designs; optimising the choice of materials; and overcoming challenges related to design, manufacturing, technology, logistics and assembly.
Brian Broderick and John Hickey
Trinity College Dublin
Modern Methods of Construction categories
Modern Methods of Construction (MMC) describes a range of manufacturing and innovative alternatives to traditional construction (DHLGH). These include approaches that span off-site, near-site and on-site pre-manufacturing, process improvements and technology applications.
Watch the video to learn the MMC Definition Framework.
Category 1
3D Volumetric / Primary Structural Systems
This category involves the manufacture of three-dimensional modules off-site that are then transported to and assembled on site to create a building. The modules may be fully- or partially-fitted out at the factory, and may include external cladding and insulation. The structural materials used are cold-formed and hot-rolled steel, precast/reinforced concrete and timber. This category facilitates the highest levels of pre-manufacture, although the building invariably requires elements of traditional construction including foundations and core. Applications of this category in residential construction are increasing worldwide, but to date has made a limited contribution to house building in Ireland, with greater prevalence in the industrial, education and healthcare sectors.
Category 2
2D Panelised / Primary Structural Systems
In this category, two-dimensional panelised and framing systems are manufactured off-site and assembled on site to create various components of the building structure including walls, floors, roofs and stairs. The extent of pre-manufacture varies and can include structural elements only, or may also include insulation, cladding, doors and windows. This category of MMC is widely employed in residential construction in Ireland. Pre-manufactured roof trusses have long been employed in house building, and current applications in new houses and apartments include other structural and building elements manufactured in light gauge steel, timber with precast concrete. There is substantial variation in the amount of traditional construction that is also required to create the entire building.
Category 3
Non-Systemised Structural / Primary Structure
In this category, individual structural components are pre-manufactured off-site and transported to the site
to be combined with other elements to form the structure of a building. This category is relevant for nearly
all forms of structural elements, and has been extensively used in residential construction in Ireland.
Examples include steel beams, columns and piles, precast floor slabs and walls, stairs and roofs. The use
of engineered timber elements in this category is also increasing worldwide. Although a well-established
part of house building and, especially, apartment building in Ireland and elsewhere, contemporary MMC
element manufacture and/or subsequent construction usually takes place within digitally-enabled workflow.
Category 4
3D Printing / Additive Manufacturing
This category relates to 3D printing of building elements. Although many traditional construction methods
can be viewed as additive processes, the specific application of 3D printing as an off-site manufacturing
technique has to date found limited application in construction. While this category may contribute to future
residential construction in Ireland, it is not expected to make a substantial contribution in the short-term.
Category 5
Non-Structural Assemblies and Sub-Assemblies
This category covers pre-manufactured non-structural components for buildings in which assembly work is
carried out in a factory setting prior to delivery to site. These assemblies can be employed alongside MMC
Categories 1 and 2 or in traditional construction projects. The category includes 3D assemblies such as
bathroom and kitchen pods, 2D assemblies for facades, walls and roofs and M&E assemblies. The diversity
of solutions covered by this category is reflected in its widespread and increasing application in Irish
building projects, including residential construction.
Category 6
Traditional Building Product Led Site Labour Reduction / Productivity Improvements
This category considers improvements to traditional building materials and products aimed at facilitating
quicker, easier and safer installation, often with reduced on-site labour or skilled labour requirements.
Examples include pre-manufactured walls and roofing elements.
Category 7
Construction Processes: Site Process Led Site Labour Reduction / Productivity / Assurance Improvements
This category involves new on-site processes to improve productivity, construction speed and safety. The
processes are characterised by the use of new technology, including digital technologies. Examples include
the integration of BIM with on-site processes, the use of augmented and virtual reality to aid assembly,
digital scanning of building components and robotics. New technologies for these purposes are being
developed and adopted by the construction sector in Ireland and worldwide and are expected to contribute
to productivity improvements in the provision of residential accommodation.
