Prefabrication, full 3D model sharing among all trades and bathroom pods built in a factory in Ohio are things that don’t happen on every project in Iowa. The $101-million, 330-room Hilton Des Moines Convention Center is a 330-room, 28-suite hotel that allows the city to compete with Omaha and Kansas City for convention business and, thanks to bridging design-build delivery, general contractor/developer The Weitz Co. fronted the entire capital cost of construction. That also gave Weitz the ability to demand prefabrication and 3D models from the entire project team.

“Every subcontractor had written into their contract that creating an exterior skin was part of their scope of work. They had to supply plumbing, electrical systems and everything that connected to it,” says Ben Bunge, project manager for Weitz. “We then virtually clashed all of those models with the design model. Once the models agreed, they were shipped out to fabrication.”

Prefabricated components included bathroom pods for all non-suite rooms, structure/exterior skin assemblies, all HVAC equipment and ducts, 80% of the plumbing, including complete drain assemblies, PEX risers, solvent, domestic water risers and aquatherm polypropylene pipe, electrical room kits, all studs and drywall, and all pre-hardware doors.

A centralized layout using Trimble Total Stations allowed all rebar and sleeves to be placed correctly via Weitz’s construction model, so there was 100% rebar modeling, sleeve modeling and 100% direct rebar fabrication accuracy. All concrete placements were made based on points from the 3D model.

When the project was completed on time, municipal bonds paid back the contractor/developer in full and Des Moines had the convention business it had been missing.