One Industry, One Classification Framework
Today, offsite methods are judged by a label, while traditional building never has to explain itself. BSI are working towards a UK standard that changes that by classifying every construction method on the same terms.
If you make, specify, build, fund or insure buildings, this standard will shape how your work is described and judged. Now is the time to make sure it gets that right. The scope is open for comment now, and we want to hear from you.
Matt Egan, Chair, BSI CB/301 Offsite and Modern Methods of Construction
Two walls, one job
Picture two walls. One is load-bearing brick and block, laid on site. The other is a light gauge steel panel, made in a factory.
Both hold up the building. Both carry their load along their length. On paper, they do the same job. The only real difference is how they were made.
Yet that is the one thing everyone focuses on. The steel panel gets labelled “MMC” and treated as a risk. The brick wall gets no label at all, because traditional building is simply the default.
A new British Standard sets out to change that by asking every wall, panel and pod the same questions. BSI committee CB/301, which I chair, is leading the work, and its scope covers every way we build, from a volumetric unit leaving a factory to a brick wall laid on site.
The way we build has moved on. Offsite has delivered far more than the “MMC” label gives it credit for, and traditional building is changing too, picking up factory-made products and new processes until the line between the two is hard to draw. Yet the way we describe what we build hasn’t changed. As the industry industrialises, that language needs to be reviewed and brought up to date. “MMC” is still shorthand for anything that isn’t traditional, and anything that isn’t traditional still has to prove itself and carry a risk premium.
You can see it in how lenders, insurers and warranty providers treat our sector. Without a common way to describe what is being built, they price the label, not the system. A tested, accredited panel system can end up in the same box as an unproven product.
A classification that only covers offsite methods won’t fix that. It would describe volumetric and panelised systems in detail and leave brick and block as the benchmark nobody questions. Ask every method the same questions (what the element does, how it is made, how it carries load) and the comparison becomes fair. Then we can talk about the real safety and performance of what we build with, not just whether it counts as MMC.
How the draft works
The draft classifies by function first. The first question is what the element does in the building: primary structure, enclosure, services or infill. The second is how it is made: volumetric, panelised, component, printed, product-led, process-led or traditional. The third is how it carries load, such as a line loaded wall or a point loaded module. Material, connection and degree of completion come after that.
Run four everyday elements through those questions and watch the brick wall take its place beside its offsite equivalents.
Element | What it does | How it is made | How it carries load |
Brick and block wall | Primary structure | Traditional, built on site | Line loaded wall |
Light gauge steel wall panel | Primary structure | Panelised, made off site | Line loaded wall |
Steel framed volumetric module | Primary structure | Volumetric, made off site | Point loaded at the corners |
Bathroom pod | Enclosure | Volumetric, made off site | Carries no load from the wider building |
Each of these answers will be codified, covering load, material, connection and more. The code format is still being drafted with the panel.
Look at the first two rows. Both walls are primary structure and both carry load along their length. The method is the only difference, and that is the question a lender or insurer should be asking.
Product-led improvements to traditional building, such as thin joint blockwork, are classified on the same basis. The MMC category falls out of the answers, so the 2019 MMC Definition Framework stays useful as an output of the classification instead of its starting point. A traditional brick wall is fully classified and has no MMC category.
Classification came up during the development of PAS 8700, the BSI specification for MMC published in 2025. The thinking was not mature enough to go into a standard at that point, so PAS 8700 leant on the MMC Definition Framework. The framework’s seven categories work well as a summary. They give no rule for deciding which category an element belongs in, and two people can put the same system in different places.
Since then CB/301 has built the logic and tested it against worked examples, from volumetric systems to traditional masonry. The draft now runs to 25 pages and has gone to the CB/301 panel for review.
BSI is now working towards a standard built on that work, and the first step is a scope and brief for public feedback.
What I’m asking you to do
The scope is still open, and this is the moment that counts: comments made now will shape the standard more than anything said once drafting starts. I am asking the industry to do three things.
Read the proposed scope on the British Standards Institution - Project and tell us what it misses. Does it cover the systems you make, specify, fund or insure?
Join the drafting panel. We need manufacturers, contractors, designers, lenders, insurers and warranty providers, and people who build in brick and block.
Send feedback and expressions of interest to me matthew.egan@by-design.group
A classification works only when the people who use it have shaped it. This one is meant to describe every way the UK builds, brick included, so it needs the whole industry in the room. Make sure you are part of it.
Comments