How Is MEP Coordinated in Modular Building Construction?

I design modular MEP so the factory can build it efficiently and the site crew can finish it quickly — those are different optimizations and both have to be satisfied. In the factory, work happens with the module open: I route mains along the module's long axis, keep branch takeoffs simple, and mount equipment where a forklift or crane can set it before the module closes. Every system is designed to be testable in the module: piping gets test caps at the boundaries, ductwork gets blank-offs, and electrical gets landing points for temporary test power. The drawings carry factory-specific information that site-built drawings never need: module designations on every sheet, the datum each dimension is measured from, shipping restraints for equipment, and weather protection for open ends during transport. I also design for the lift — equipment mounted high in a module shifts the center of gravity, so I coordinate rigging points with the structural engineer and confirm that no MEP component interferes with the crane picks.

The interconnection plan is the document the whole project lives or dies by. I show every duct joint, pipe coupling, conduit continuation, and control wire landing at the module boundaries, each with a tag that matches a schedule listing the connection type, size, access requirement, and test procedure. Chases are stacked vertically through the modules so risers run straight, and I hold a clear working zone at each boundary — typically a removable ceiling panel or access door positioned exactly over the joint. Connection types are chosen for field reality. Grooved pipe couplings and no-hub fittings tolerate the small misalignments that field setting produces; gasketed flanged duct joints with draw bands go together fast in tight chases; electrical connections use terminal blocks or plug connectors in accessible junction boxes rather than splices buried in walls. For controls, I home-run the low-voltage wiring to a panel in each module and land the inter-module trunk at a single labeled terminal strip per boundary, so the controls contractor can ring out the building one boundary at a time.

Commissioning a modular building means proving the factory work and the field joints separately, then proving the integrated building. I write the split into the commissioning specification so nothing falls between the factory and the site. • Factory: witnessed pressure tests on all piping, duct leakage tests on assembled runs, insulation verification before close-up, and electrical continuity and megger testing — with reports shipped with each module • Receiving: verify certification labels, confirm no transit damage to MEP components, and check that every interconnection stub matches the coordination drawings before modules are set • Field joints: re-test every site-made pipe joint, verify duct joint sealing, torque-check electrical terminations, and photograph concealed fire-stopping before close-up • Integrated building: full-system startup, functional performance testing of HVAC sequences, domestic water balancing, and whole-building air leakage testing to prove the joints perform as designed