Prefabrication experiments - 523 - Standards and In-factory Inspections

 

Buildings erected using factory-made subassemblies or large volumetric modular chunks must conform to the same codes and regulations that apply to conventional construction methods. Fire ratings, means of egress, dimensional criteria, and sound transmission are all defined by prescriptive construction assemblies. These provide the basis for minimal construction quality to ensure the health and safety of occupants as well as a building's stability and durability. Architects, other professionals or authorities having jurisdiction (AHJs) supervise or inspect assemblies on site to confirm conformity with building codes. 

 

The logistical nightmare associated with having to adapt factory finished elements on site argues for their upstream inspection and for any corrective measures to be applied in the factory before they are delivered to site. Industrialized building is effective when it is part of a streamlined and cost-efficient design-to-delivery process. In Canada, the CSA A-277 standard provides an outline for qualifying factories and certifying that modular volumetric sub-assemblies, prefabricated buildings or prefabricated panels meet minimum requirements before they leave the factory.

 

A277 provides requirements for  « a) certification of the factory quality program;  b) certification of the prefabricated product; c) auditing of the factory quality program; and  d) in-factory inspection of the prefabricated product.» First developed for the prefabricated housing sector as an evolution of the still applicable CSA Z240MH which states the minimal requirements for manufactured homes fabricated on a steel chassis, CSA-A277 can apply to all building types and is being used to certify factories producing modules for schools, hospitals and collective housing blocks. 

 

Third party independent inspection agents certify factories and their output.  AHJs and professionals can cooperate with manufacturers, ideally during the design stages to understand their processes and outline the required scope of stakeholder engagement to account for in-factory certifications. As is the case with many other modularized factory-made components, unitized curtain walls, mechanical equipment, kitchen cabinets, and specialized devices, conformity is established as part of a harmonized inspection process.  

 

CSA standard series Z250, Z251, Z252 (not yet referenced in Canadian codes) further regulate modular construction considering the current uptake of offsite construction to standardize elements that include transporting, setting, juxtaposing and assembling factory-produced boxes.

CSA A277 conformity sticker