Chapter 12: On Site
Designing certainty in the vertical city

How Mace Construct turns the inherent risks of tall buildings into predictable delivery

Image: Chapter Living, London Bridge

Cities will continue to grow upwards, nowhere more so than London. In the Square Mile alone, demand for high‑quality, sustainable workspace is intensifying as land scarcity, job growth and occupier expectations converge. The City of London Corporation recently reiterated that the Square Mile will require around 1.2 million square metres of additional office space by 2040 to remain globally competitive, driven by rising employment and a chronic undersupply of best‑in‑class buildings. Here, Ged Simmonds, Private Sector Managing Director at Mace Construct, explores some of the approaches being taken to achieve this growth.

Despite decades of experience, the construction of tall buildings remains one of the built environment’s most risk‑exposed endeavors. Programme overruns, constrained logistics, safety challenges and productivity loss are not exceptions in high‑rise delivery – they are statistically normal outcomes when complexity is underestimated or treated sequentially rather than systemically.

The industry must start from a different premise. Tall buildings are not simply vertical extensions of standard construction; they are dynamic production systems in which flow, logistics, methodology and data must be designed with the same rigour as structure and form. Our approach is not about removing constraints – it is about engineering certainty within them.

The reality of tall‑building risk
Independent research consistently highlights the same pressure points in high‑rise construction: constrained sites, poor coordination between trades, vertical transport bottlenecks, late material delivery and safety risks associated with working at height. Productivity loss is most acute not at height, but below ground and during early sequencing, where limited frontage, deep basements and logistical congestion absorb time long before the structure rises. Meanwhile, urban logistics research shows that poorly integrated delivery planning remains one of the most under‑managed drivers of delay in dense city environments.

Methodology as a strategic choice
When methodology is chosen late, programmes inherit risk they can no longer remove, only absorb. Therefore, construction methodology is not a default engineering preference – it is a strategic programme decision. Techniques such as top‑down construction are widely recognised for their ability to unlock parallel workfaces and reduce programme exposure on constrained urban sites. However, these approaches introduce their own risks if not rigorously planned. The differentiation lies in how methodology is deployed: Integrating structural design, temporary works, logistics and programme modelling from the outset, allowing trade-offs to be made consciously in pursuit of schedule certainty.

Unlocking transformative potential: Offsite manufacture at scale
Offsite manufacture increasingly forms part of how certainty is designed into complex schemes. For tall buildings and other highly-constrained environments, the shift from sequential, trade‑led construction to component‑based delivery allows risk to be addressed earlier, under controlled conditions, and at scale.

At Mace Construct, our Construction to Production (C2P) approach reframes offsite manufacture not as a product choice, but as a programmatic decision, aligning design, procurement and installation around repeatable, quality‑assured components.

Edge London Bridge

This approach has been applied across a range of projects, from high‑rise student and mixed‑use developments to complex transport environments, using prefabricated structural elements, MEP assemblies and bathroom pods to reduce site congestion, compress critical paths and improve safety by transferring work away from height and into factory settings.

On our scheme at Chapter London Bridge, C2P‑led delivery enabled accelerated floor cycles through the parallel installation of structure, core, services and facade. The result was an estimated programme acceleration of five months. While on our project at 40 Leadenhall, extensive prefabrication of over 1750 MEP components demonstrably improved productivity, quality and carbon performance. From a 20% reduction in embodied carbon, to a 200% boost to installation productivity.

Crucially, offsite manufacture only delivers its full value when integrated early, with design fixed to suit manufacture and logistics sequenced to suit installation. When applied in this way, it becomes a powerful complement to methodology selection, creating predictability upstream and enabling reliable flow downstream.

Edge London Bridge

Logistics as a core production system
Urban logistics remains one of the most persistent causes of high‑rise underperformance. Limited laydown space, restricted delivery windows and competition for crane time create friction that cascades through programmes when left unmanaged. Mace Construct treats logistics as a primary production system. Just‑in‑time delivery models, vertically sequenced construction rhythms and deliberately designed crane and hoist strategies are embedded early, creating predictable cadence rather than volatile peaks of activity.

Data that drives decisions
Digital tools deliver their greatest value when used to inform real‑time decision‑making. At Mace Construct, live data is used to test assumptions continuously: Analysing crane utilisation, monitoring vertical transport demand, tracking weather‑related productivity shifts and aligning supplier performance with actual site conditions. This allows teams to intervene early rather than react late, reducing uncertainty rather than simply reporting it.

Designing safety into the system
High‑rise construction remains one of the most safety‑critical areas of the industry, not simply because of height, but because of the complexity, density and pace at which work is undertaken. Our work on high-rise buildings such as Highpoint involved many bespoke mitigations, full-height screens and edge protection were used progressively. Elsewhere at Chapter Living in London Bridge, the team used fully enclosed floorplates to reduce exposure at height. At Mace Construct, safety is understood as an outcome of how work is designed, led and experienced on site. It is shaped as much by everyday behaviours as by formal controls. By reducing unplanned movement, stabilising logistics flows and eliminating clashes before work begins, we create conditions for safer delivery.

Just as importantly, we focus on the ethos that sustains those conditions by encouraging teams to pause, question, engage and intervene early when something does not look right. Safety is embedded in both the system and culture of delivery, reinforced through leadership visibility, open dialogue and positive reinforcement, rather than added as an afterthought.

A blueprint for the vertical future
Cities will continue to densify. Sites will remain constrained and programmes unforgiving. The industry cannot rely on traditional sequencing and fragmented logistics to meet this demand. The ideal approach to tall buildings is built on a simple belief: Certainty is designed, not discovered. By treating methodology, logistics, data and safety as integrated components of a single production system, we turn the inherent constraints of tall‑building construction into controlled momentum.

In the vertical city, success belongs not to those who build fastest at height, but to those who design flow from the ground up.

www.macegroup.com/construction-services

At Chapter Living in London Bridge, the team used fully enclosed floorplates to reduce exposure at height