Productivity is one of the most discussed subjects in UK construction, and one of the least clearly defined.
According to Mace Construct’s Build Smart, Build Better report, UK construction productivity is roughly 20% lower today than it was in the 1970s. Between 1997 and 2022, it improved by only around 1%, compared with 182% in manufacturing. [resources.macegroup]
But the report’s most useful finding may not be the headline you read. After analysing 234 of its own projects, Mace found that productivity is not one thing. A project can perform well on one measure and poorly on another. So when clients, contractors and suppliers say they want ‘higher productivity’, they may mean three different things. [resources.macegroup]
The three measures of productivity
Output per hour
Measured as gross value added per worker hour, this is the rate at which labour time is converted into measurable output: the value of work completed divided by the hours worked on site.
It is the measure most people picture when they hear the word productivity, and the one that rewards pace.
Value per worker
Gross contribution per worker shows how much of the work being done ultimately contributes to commercial value.
A busy site is not necessarily a valuable one. Hours spent on clashes, coordination failures and rework keep people occupied without always moving the project forward.
Margin retention
Mace measures margin erosion as a percentage of bid value. In practice, it shows how much of the commercial value forecast at the start of a project matches what’s delivered.
It answers a different question again: not how fast the work was done but whether the project finished as planned.
Mace found that the three measures show little correlation. The one meaningful link was between value seen per worker and margin retention. A project can convert labour hours efficiently into output and still fail to turn that into commercial value. [resources.macegroup]
This also helps explain why clients and contractors can talk past each other. One may be focused on programme certainty, another on hourly output and a third on margin.
Where these measures are influenced
The common thread is timing: MMC and digital coordination deliver most value when they are looked at early in the design. Where critical design decisions are still being taken at RIBA Stage 4 or 5, the opportunity for prefabrication has often already passed. Work that could have been made off site ends up being built on site, under programme pressure.
The cost of getting this wrong is high. The Get It Right Initiative estimates that avoidable errors cost the industry around 5% of project value directly, and between 10% and 25% once indirect and unmeasured costs are included. [getitright.uk]
In Mace’s data, modern methods of construction showed up in value per worker rather than hourly output. Projects with higher use of MMC generated around 50% more commercial value per worker on average than comparable projects of similar size and type. Digitally mature projects retained around £1 million more of their forecast margin. [resources.macegroup]
What this means for riser delivery
Risers sit where structure, building services and fire performance meet, yet they are often left until late in the design process. Each of the three productivity measures is affected by when and how risers are resolved.
Output per hour
Traditional riser delivery can involve forming a floor void then adding temporary concrete shuttering. Temporary edge protection is then required to be installed around the void to protect against falls from height.
AlphaRiser is incorporated from the start of the programme, as the frames are assembled. Its outer frame integrates into the floor slab and provides the shuttering for the slab edge. That removes several separate site operations and the handovers between trades that come with them. As AlphaRiser comes supplied with the permanent floor grating already installed, the need for temporary edge protection is also eliminated, thus removing two areas of temporary works from the build programme.
Value per worker
The more of the riser that is designed and manufactured in advance, the more site labour goes into installation rather than building, adjusting and correcting temporary works.
The unit can be installed before the final mechanical, electrical and plumbing design is confirmed. Once MEP works begin, penetrations can be marked up and cut through the lightweight glass-reinforced plastic grating to allow services to pass through. Standardisation, modularisation and design for manufacture and assembly help reduce the number of interfaces and operations required on site.
Margin retention
Rework and late changes are among the ways a project can lose margin. This is where early involvement matters most.
Comtec’s early design support, including coordination of drawings and building information modelling, helps resolve riser design before it becomes a late change. For instance, at 2 Finsbury Avenue, Comtec supplied and installed 1,047 AlphaRiser floor units across 57 floor levels, with the solution delivered 16 weeks earlier than the original programme. This allowed other packages to start sooner and helped reduce overall build time.
The earlier, the better
The three measures of productivity may not move together, but they share a common starting point, and that is decisions made early.
A project that plans its riser strategy at design stage gives itself the best chance of performing well across all three. Fewer site operations, less rework and a more predictable programme can all follow from resolving the same issue earlier.
As the industry faces pressure on labour, cost and delivery certainty, the conversation is less about how hard a site is working and more about how well the work was set up before anyone arrived. If you are planning a project and want to understand how riser strategy could support your programme, talk to Comtec about an early technical consultation.
