Market Quarter Mixed-Use

A nine-storey mixed-use scheme in Sheffield — retail at ground, offices above, residential at the top — where the four delivery packages were contracted to separate design teams who had never shared a model before. My role as Coordination Lead was to make sure the scheme could be built as one building even though it had been designed as four. The mechanism was a single federated coordination model, rebuilt nightly, holding all four discipline models under one set of tolerances.

The strategy was decided before the first federated file was built. Each discipline exported to a common origin and a common IFC schema; the structural engineer’s model came in at LOD 350, the facade package at LOD 400, MEP at LOD 350 with reserved service zones, and our architecture at LOD 300 for coordination with LOD 400 assemblies flagged for the detail stage. The federated file ran to 18 GB at peak, which is why the review process was as engineered as the geometry.

Clash matrix and tolerances

Clash detection is only as good as the rules you run it under. The matrix defined four interfaces — structure-to-MEP, structure-to-facade, MEP-to-facade, and all-to-architecture — each with its own tolerance and severity. Structure-to-MEP was run hard at 50 mm, because a beam that crosses a duct is a real cost. Structure-to-facade was run at 25 mm with the facade attachment brackets modelled, so we caught the case where a bracket would have landed in a precast panel joint. Every clash was logged, assigned, and tracked through a responsibility matrix that named the lead on each side of the interface, so nothing bounced between teams.

The basement plant layout was the hardest coordination zone in the scheme: four storeys of structure, two of plant, and a single loading bay shared by all uses.

Weekly coordination reviews

Each week the federated model was reviewed zone by zone, on the schedule set out in the coordination zone plan — basement, plant deck, ground-floor retail, office cores, and residential slabs. Plantroom clashes were resolved by reserving voids in the structure at the review rather than letting the MEP engineers fight the structure engineers in isolation; the void reservation register became a contractual document in its own right. Sign-off was formal: each discipline lead signed the coordination report, and un-resolved items were escalated to the project director with a fixed date.

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The scheme went to construction with the clash log effectively empty and the basement plant room never redesigned once the works were on site. The coordination model, handed over at completion, became the baseline for the FM team — proof that four design teams can build one building if you give them one truth to work against.