The standards represent a leap forward for MBI. “Just to have standardized definitions is a huge deal,” says Hardiman. “The terminology was all over the place,” he adds.

In the standards, offsite construction is defined as a modular building, component or panelized system designed and constructed “in compliance with this standard” and “wholly or in substantial part” fabricated or assembled in manufacturing plants for installation—or assembly and installation—on a separate building site. The offsite project “has been manufactured in such a manner that all parts or processes cannot be inspected at the installation site without disassembly, damage to, or destruction thereof.” 

The aim is to bring consistency to offsite projects—for manufacturers, building teams and regulators. The standards, which are complementary, also are part of an effort to lower barriers to trade for offsite products, which often have to navigate a patchwork of regional regulations.

This is accomplished in part because the standards offer a path for third-party inspection at the plants, before finishes hide structure, wiring, ductwork and plumbing, says Ryan Colker, ICC’s vice president for innovation. This is important because building officials are not typically authorized to travel outside their jurisdictions. 

Until the city council adopted the standards, that was the situation in Salt Lake City. A modular builder outside the city wanted to sell accessory dwelling units, typically sited in backyards, to city homeowners. The modular ADUs were not allowed by code because they were not regulated by the city, says Orion Goff, Salt Lake City’s deputy director of community and neighborhoods and former building official.

A major motivator for the standards is that the 35 states that regulate modular construction have slightly different requirements for design review and approval, permitting and inspection. The same is true for jurisdictions that regulate modular projects using codes written for onsite construction. 

That’s a big problem for building teams, says David R. Tompos, a 50-year veteran of modular construction who chaired the standards’ committee. It makes it difficult for manufacturers of modular units to ship to sites outside their jurisdictions and cumbersome for building teams that work in many jurisdictions because they have to follow different requirements for submittals, quality-control manuals and inspection, he says.

The situation “wastes a lot of time” and causes unnecessary expense, adds Tompos, director of marketing for ICC NTA, a third-party inspection service for offsite projects, owned by ICC. 

Though each jurisdiction will likely have its own addendums to the standards, if states and jurisdictions adopt the documents, Tompos figures 99% of the information asked for would be identical. 

Captures Best Practices

Beyond the purchase cost of the standards, Colker figures there shouldn’t be any additional costs associated with use of the standards because they largely capture the best practices of many offsite manufacturers and designers.

But building teams, accustomed to an onsite process, will have to adjust to a new one, Colker adds. To help, ICC offers a course on the standards.  

Efforts to get the standards, which do not apply to HUD Manufactured Housing, included in ICC’s 2024 International Building Code, did not pan out. ICC’s International Residential Code change process is under way. 

ICC and MBI aren’t waiting for adoption. “We are trying to get each state to directly adopt the standard or at least modify their regulations to be more in sync with the standards,” Hardiman says.

For example, in Washington state, where approvals were taking 18 to 22 weeks due to staff shortages, MBI began working with the Dept. of Labor & Industries in October. Consequently, the state began implementing third-party inspections and approvals in the short term to help clear up the backlog. 

ICC and MBI are not done yet in their push to facilitate modular work through standards. In December, they began developing Standard 1210, which will address requirements for mechanical, electrical and plumbing system elements, energy efficiency and water conservation.