- Faster delivery. While some elements of the development process (such as planning) remain the same whatever the type of construction, the ability to pre-manufacture elements away from site can generate significant programme savings. Estimates for this vary, but around one third to one half of the construction period itself can currently be eliminated by utilising MMC systems.
- Faster delivery of homes/income/return on investment. The natural consequence of shorter programme times is that homes are available to use sooner. This means residents can be housed sooner and that the investment in new homes can be recouped through rent sooner. This latter point is a key reason behind MMC being used widely in the Build to Rent and Student Accommodation sectors, where the initial investment in construction can be realised sooner by the institutional investors who build and own the homes, meaning they can develop more homes more quickly using MMC. The same logic and benefit will apply to affordable housing providers, who are building to own and rent an asset.
- Quality. An assembly led manufacturing process can help to alleviate the potential for poor oversight of build and appropriate supervision that can happen in traditional construction. Employees are easier to oversee when they are completing tasks at a consistent workstation, supervision is easier to achieve as one inspector can monitor many builds, and a factory setting with permanently employed staff means that training and competency in workers is easier to control. Clear checking points in an assembly line are easier to sign off for quality assurance, for example confirming the presence and proper installation of fire barriers.
- The construction workforce. There is insufficient capacity within the construction industry in its current form to significantly increase the volume of homes it delivers. The industry is amid a skills shortage which is affecting both the volume and the quality of homes being delivered. This has been demonstrated most recently by reports showing that 46% of skilled foreign construction workers have been lost as a result of Brexit and the Covid crisis. MMC utilises a largely different workforce to traditional construction, encouraging the sustainability of the sector and the clean factory-based working conditions have been shown to be effective in attracting a new demographic to the industry and diversifying the workforce.
- Funding. Government policy has been moving to a position of support for MMC for at least the past five years and this is now most visibly seen in the requirement of Homes England (HE) that strategic partners deliver 25% of their programme as MMC, and more generally in both HE and the Greater London Authority (GLA) encouraging all bidders to consider MMC as an option on sites.
In 2019, a MMC definition framework was developed by a government and industry working group on MMC. It covers seven MMC Categories.
The framework was developed to regularise the term ‘MMC’ by defining the broad spectrum of innovative construction techniques being applied in the residential market.
- Category 1 – Pre-Manufacturing – 3D primary structural systems
Category 1 volumetric, three dimensional ‘boxes’ are manufactured in factories and delivered to site. Typical systems include timber, steel or cross laminated timber (CLT). This category has the highest level of pre-manufacture.
The Category 1 segment of the offsite market is more mature than some other categories. There are a number of large-scale Category 1 factories in the UK that have already been delivering residential MMC homes for some years. - Category 2 – Pre-Manufacturing – 2D primary structural systems
These are two dimensional panelised systems, manufactured in factories and assembled onsite to form a structure. There are many differences within 2D categories: standard timber, cross laminated timber (CLT), steel, structural insulated panels and hybrid systems. Category 2 systems have the ability to be manufactured to a client’s own individual designs and house types. They can provide bespoke solutions to sites that might already have planning, without housing organisations having to go back to the drawing board. 2D panelised systems are also easier to transport so they are more suitable for sites with access issues.
The Category 2 segment of the offsite market is evolving rapidly with new products and manufacturers emerging all the time.
- Category 3 – Pre-Manufacturing – Non systemised structural components
This includes the use of pre-manufactured components to form part of the structure of a building, mostly made from timber or concrete.
Typical types of Category 3 MMC components are driven or screw piles, pre-fabricated pile caps or ring beams, columns, walls and/or beams, floors, integrated columns and walls and beams, staircases and roofs. - Category 4 – Pre-Manufacturing – Additive Manufacturing
This type of MMC solution relates to the 3D printing of parts of buildings and it can be done remotely or onsite.
Although this form of MMC is not available for widespread use in construction projects currently, it is expected to be in the future. - Category 5 – Pre-Manufacturing – Non-structural assemblies and sub-assemblies
Category 5 covers pre-assembled components that do not form the structure of a home and can be used in isolation in an otherwise traditionally constructed project.
There are two main types of MMC Category 5: 3D components such as pods and 2D components such as façades, floors and walls. - Category 6 – Traditional building product led site labour reduction/productivity improvements
This category comprises traditional building materials that have evolved so that they are quicker, easier and safer to install. They are either large format versions of traditional materials, or materials that have been developed to be easier to install with less reliance on onsite labour.
Category 6 solution types include internal walls, external walls, roofing finishes, materials that have been specifically cut to size, e.g. pre-sized plasterboard and also materials that have been adjusted to be easier to install, e.g. brick slips. - Category 7 – Site process led labour reduction/productivity improvements
This includes the use of systems and processes onsite to drive productivity by removing unnecessary work stages, enabling better and faster installation and improving health and safety.
Examples include measures to encapsulate a site to secure weather-proof conditions, standardised temporary work (e.g. a modular scaffold), use of BIM connected to onsite workflows, visual aids such as AR or VR, physical aids such as exoskeletons and productivity tools such as GPS.
- Design – for example, how materials respond to fire and how firefighters might respond to the materials, such as flooding with water and creating content damage
- Habitation – how people use the home requires understanding of how structures are different from traditional brick
Resources
Ministry of Housing, Communities & Local Government (MHCLG) MMC definition framework
MMC is the term often used collectively for a wide range of non-traditional building systems, which are categorised in the report.
Homes England MMC research study
This study seeks to understand the impact of MMC on the delivery of homes. This page includes a full description of its themes and metrics.
NHBC report on modern methods of construction
National House Building Council’s (NHBC) report looks at the history of non-traditional housing and pulls out the best homes from the past to inform the homes of the future.
Build Homes, Build Jobs, Build Innovation: a blueprint for a housing led industrial strategy
A report on how Government can stimulate demand for modular housebuilding
Membership is open to professionals across the social and affordable housing delivery ecosystem including Registered Providers, local authorities, central government, MMC suppliers and others who want to take an active role in driving an uptick in social and affordable housing delivery.
