Design-Build or Supply-and-Set Modular?

There are two common ways to buy a commercial modular building. In supply-and-set, the manufacturer builds, delivers and sets the modules, and someone else prepares the ground they sit on. In design-build, one team designs the building, engineers it, builds it, does the site work and hands over the keys. Neither is always right. This article sets out what each covers, where the risk sits, and how to choose.

Supply-and-set: the building, delivered and set

A typical supply quote covers the building manufactured and inspected in the plant, trucked to site, craned onto its foundation and connected. The owner, or a contractor the owner hires, prepares the site, the foundation and the service connections to the manufacturer's drawings.

It works well when the building is one of a manufacturer's published plans, the site is simple, and the owner already has a contractor they trust. The owner holds the interface: if the foundation is late or out of level, the set waits. How to write a tender for this route is covered in the modular building RFP checklist.

Design-build: one team, one schedule

In design-build, one company is accountable from concept to completion. The design, the engineering, the factory build, the foundation, the services and the set are planned together, and the owner has a single point of contact.

The main gain is the schedule. Modular saves time because the site work runs while the modules are built, and that only works if the foundation and the factory are on the same plan. When one team owns both, the foundation is ready when the modules ship. At Herauf, our own crews do the site work, from excavation to the day the units land, and the handover includes the documentation, warranties and certifications.

Where the risk sits

• Interfaces. In supply-and-set, the owner manages the line between the site contractor and the manufacturer: anchor points, service stub locations, crane access. In design-build, that line is inside one contract.
• Design control. Supply-and-set usually starts from a published plan. Design-build starts from how the building will be used, from a published plan, your drawings or a blank sheet.
• Changes. Either way, decisions have to be made before manufacturing starts. A late change costs more in a factory than on a site.
• Tendering. Public funders may set the contract form. Manitoba's child care building fund, for example, expects a CCDC 2 stipulated price or a CCDC 14 design-build stipulated price contract after a tender.

How to choose

Choose supply-and-set for a single catalogue building on a site you can prepare yourself. Choose design-build for a project of several modules, with a foundation and services that need to be designed with the building, or when you want one company responsible for the whole result. At Herauf, design-build is for commercial projects of several modules, typically $2 million and up.

Either way, every Herauf building is built indoors, meets or exceeds CSA A277 and the National Building Code for climate zones 6 to 8, and is set in days. See design-build modular construction for how the process runs, or send your site and timeline through the quote form.