IN Brief:
- Mace Construct says workforce turnover is costing UK construction around £1.3bn each year.
- The contractor’s analysis covers more than 200 projects and links churn to lost productivity and knowledge.
- The report calls for stronger productivity measurement, earlier design decisions, standardisation, and workforce stability.
Mace Construct has warned that workforce churn is costing UK construction around £1.3bn a year, after analysing productivity across more than 200 projects.
The contractor’s Build Smart, Build Better report links high turnover on construction sites to lost output, reduced continuity, and disappearing project knowledge. On a 500-worker project, the report estimates that churn can cost around £2,266 in lost output every hour. On a 2,000-worker project, the figure can rise to nearly £20,000 an hour.
Mace says an 18-month project with 500 workers could lose around £5m in output through churn-related inefficiency. The report places workforce stability alongside earlier design decisions, standardisation, offsite manufacturing, collaborative delivery, and better productivity measurement as central levers for improving construction performance.
Construction has spent years discussing productivity while often leaving the conditions that suppress output largely intact. Large project teams are assembled and disbanded around individual schemes, while skilled labour, supervisors, subcontractors, and managers move between projects with limited continuity. Each change forces teams to rebuild site knowledge, working relationships, and familiarity with the programme.
The industry’s commercial structure reinforces that instability. Contractors are under pressure to price tightly, transfer risk, and manage cash carefully, while subcontractors often face late design change, payment pressure, and fluctuating workloads. Debate around a potential ban on construction retentions has highlighted how payment practice and risk allocation can weaken collaboration before site productivity is even considered.
Workforce churn affects more than labour efficiency. It influences safety briefings, quality control, sequencing, logistics, supervision, and defect prevention. A site team that understands the project, the programme, the client’s priorities, and the interfaces between trades is more likely to identify problems early. A constantly changing workforce spends more time relearning context and less time improving output.
The report’s focus on early design decisions also points to a recurring weakness in project delivery. Productivity is often lost before workers arrive on site, through late design changes, unresolved interfaces, procurement delays, and unclear buildability decisions. Once those issues reach the site team, the available options are narrower, more disruptive, and more expensive.
Modern methods of construction and offsite manufacturing can improve productivity, although they depend on early certainty. Standardised components, prefabricated assemblies, and digital coordination all require decisions to be frozen early enough to protect the manufacturing sequence. If design churn continues, offsite production can inherit the same instability as traditional construction.
The skills dimension adds further pressure. The UK construction workforce is ageing, apprenticeship numbers remain weak in several trades, and capable supervisors are in strong demand. Losing experienced people from a project can remove far more than labour hours. It takes away practical knowledge of sequence, local constraints, supplier performance, site logistics, and client expectations.
Mace’s ambition to become the most productive major UK contractor by 2030 places the report within a wider internal change programme, but the numbers carry wider relevance. Productivity is often discussed in abstract terms; attaching a financial cost to churn gives project teams a clearer basis for intervention. Stabilising teams, improving planning, retaining knowledge, and measuring output can be treated as commercial controls rather than general management aspirations.
The sector is unlikely to solve productivity through a single reform. Digital tools, offsite manufacturing, improved procurement, stronger supervision, workforce stability, and better payment practice all need to reinforce one another. If churn remains accepted as a normal feature of project delivery, the industry will continue to lose output while being asked to build more infrastructure, housing, and industrial capacity with a constrained workforce.
