Code Compliance for Modular Construction 

Every new building in Canada has to comply with building codes—whether site- or factory-built. Factory-constructed buildings require an “off-site review” to show the local authority that the elements constructed in the factory comply with code. This is typically accomplished through certifying the entire factory construction process to the CSA A277 certification standard—just like building products installed in buildings are certified. Find out how this works and the how the codes and standards apply. 



National codes are model codes and their provisions only become requirements when they are adopted by the local authority having jurisdiction. This means that all buildings, including factory-built buildings, must comply with the locally applicable building codes and regulations in effect, and that they should be checked, verified and inspected against the requirements in the location they are built in. 

When it comes to local requirements for factory-based construction, there are differences across the provincial and territorial codes. Some jurisdictions require CSA A277 certification to verify that factory-constructed buildings comply with local requirements. 

This table shows where CSA A277 certification is REQUIRED by a province or territory—as in Alberta, Quebec and the Yukon—and where it is RECOGNIZED or ACCEPTED—either by provincial/territorial regulation or through municipal policy or regulation. 


How does certification work? 

Certification to CSA A277 must be conducted by a certification body accredited by the Standards Council of Canada and recognized by the authority having jurisdiction. The certification body provides: 

  • certification of the factory’s quality system and quality program, and 
  • certification of the buildings, modules, or panels produced in the factory as complying with applicable local regulations (including requirements for professional involvement where applicable) 

The certification body oversees the in-plant quality process, including identification of qualified personnel and responsibilities, sign-offs and record-keeping, and conducts annual audits and random inspections.  

This SCC website lists the accredited certification bodies for a given scope. 

To find certification bodies accredited for in-factory construction, it helps to know the International Classification of Standards code for buildings and systems: 91.040.99. 


Scope of certification/accreditation 

The CSA A277 standard can be used to certify all types and sizes of buildings and occupancies, as well as modules and panels. The buildings, modules and panels can be constructed of any building material (including used materials), provided they comply with the building code or regulation in effect at the installation location. 

The buildings, modules or panels that can be certified in a particular factory are specified in the scope of the factory’s certification—for example, a factory’s scope could include just Part 9 single-family houses, or all Part 9 buildings, or Part 9 buildings and Part 3 assembly occupancy.  

In addition, the certification body’s accreditation similarly specifies the products it is eligible to certify, which depends on the qualifications of the certification body to evaluate design and construction of buildings of varying degrees of complexity.  

In other words, the types of buildings, modules or panels for which a factory is certified may be limited by the capabilities of the factory, or by the capabilities of the certification body. 

Information on factory certifications can be found on the websites of the certification bodies, and information on the qualifications of the certification bodies can be obtained from the Standards Council of Canada. 

Inspections and documentation 

Building elements that are built on-site (e.g. the foundation) are inspected at the site. Elements built in the factory are constructed and inspected in the factory for conformance to the local requirements in effect at the destination site. The factory construction process and the need to satisfy the procedures outlined in CSA A277 result in detailed documents available to support the permit process.  

Every building produced in a certified factory has a unique serial number assigned to it, and the associated documentation includes a travel log with the factory checklist, all inspections and testing completed, shipping documentation, and all the design documents. 

Design documents include design schedules for roof and floor trusses, ridge beams, foundation details, plumbing and electrical schematics, heat loss calculations, ventilation designs, and cross-section and floor plan drawings. Where other specific documents are required (e.g. letters of assurance) they are also supplied with the building when shipped. 

Standards for factory construction

Standards applicable to factory-constructed homes and buildings include: 

CSA A277 Procedure for certification of prefabricated buildings, modules and panels 

The CSA A277 standard is the primary standard for offsite construction compliance assurance. It was first published in 1972 and enables factories to demonstrate conformity to local building codes for the buildings, modules and panels they build. The standard provides a framework for certification programs for factory-constructed buildings, building modules, and fully or partially closed panels for panelized buildings. It applies to both residential and non-residential buildings, and the requirements of the Standard are consistent with the requirements for the certification of manufacturers according to CAN/CSA-ISO 9001. 

CSA A277 is an “administrative” standard. It does not provide technical requirements—it details the procedure for certifying compliance of factory-constructed buildings or components with the technical requirements of the locally applicable building code and regulations. Because the CSA A277 standard is an administrative document, it is not directly referenced in the National Building Code. However, CSA A277 certification may be relied on whether the standard is directly referenced or not—the same as any other product certification. 

CSA A277 is discussed in the Appendix of the National Building Code for Division A, which says that if a factory-constructed building bears the label of an accredited certification agency indicating that compliance with the Code has been certified using the CSA A277 procedure, the accepting authority will have assurance that the concealed components do not require re-inspection on site.  

Clause 4.1.1. of the CSA A277 standard says that you must comply with the local codes and regulations in force. So, in a province or chartered city that has enacted its own building code, those local codes would apply to the construction of a factory-built building. If there are no local codes or regulations in force, the standard stipulates that the building must be designed and constructed to comply with the National Building Code or the CSA Z240 MH standard (where recognized), along with other national codes as applicable. This also applies to other codes, like the Canadian Electrical code for example. 

Visit the Canadian Standards Association website here to purchase a copy of CSA A277 Procedure for certification of prefabricated buildings, modules and panels. 


CSA Z250 Process for Delivery of Volumetric Modular Buildings 

CSA Z250 describes a process for the completion of modular buildings where modules are constructed in a factory. This standard is helpful to inform project management for large multi-storey buildings, specifying procedures for: 

  • design 
  • quality control in modular manufacturing 
  • approvals 
  • logistics, transportation and storage 
  • non-modular and modular sitework 
  • lifting, placement, and setting 
  • installation and finishing  
  • commissioning and handover 

The Standard does not cover the procedure for in-factory certification of buildings, modules, or panels, which is covered in CSA A277

Visit the Canadian Standards Association website here to purchase a copy of CSA Z250 Process for delivery of volumetric modular buildings. 


CSA Z240 MH Series Manufactured homes 

Some jurisdictions reference or recognize the CSA Z240 MH Series for compliance with local requirements. The application of Z240 MH is limited to one-storey, single-family detached houses. Most of the requirements mirror those of the National Building Code, but there are some differences, such as increased requirements to provide durability during transport. 

The National Building Code references Z240.2.1 Structural requirements for manufactured homes, which provides a deformation-resistance test for both site- and factory-built buildings. Buildings and modules that pass this test may be installed on point-load surface foundations (see CSA Z240.10.1) even if the soil is subject to moisture movement. 

Visit the Canadian Standards Association website here to purchase a copy of CSA Z240 MH Series Manufactured homes. 


CSA Z240.10.1 Site preparation, foundation, and installation of buildings 

The National Building Code references CSA Z240.10.1 Site preparation, foundation, and installation of buildings (which is not actually part of the CSA Z240 MH Series). CSA Z240.10.1 contains requirements for surface foundations where buildings (not just houses) comply with the deformation-resistance test provided in CSA Z240.2.1 Structural requirements for manufactured homes. This standard is applicable to both factory- and site-built buildings. 

Visit the Canadian Standards Association website here to purchase a copy of CSA Z240.10.1 Site preparation, foundation, and installation of buildings



When a factory-constructed building bears the label of an accredited certification body, the certification body guarantees that the work completed in the factory meets the requirements of the codes and regulations in effect at the installation site. This label (and the associated documents) provide local inspectors with assurance that concealed components and the portions of the building that were constructed in the factory do not require re-inspection on site. 

A label is applied to the building when it is shipped from the factory that shows that the home was produced in a certified factory in accordance with applicable local codes and regulations—as detailed on the specification sheets inside the house. 

In whole buildings, a specification sheet is typically found on or near the electrical panel—somewhere where it is unlikely to be removed. For modules and panels, the sheet is provided to the building owner and retained with the building. The specification sheet provides the information needed to determine if the building has been designed and constructed for the installation location: 

  • to address the wind, snow and earthquake loads at the installation site 
  • to provide adequate resistance to precipitation ingress  
    (for some locations, if there a capillary break inboard of the cladding) 
  • to comply with the energy efficiency requirements for the climate zone—overall energy performance or thermal resistance of insulation 
  • outside design temperature used in heat loss calculations 
  • installed or supplied appliances (make, model, energy type) 
  • complete electrical rating 
  • if applicable—whether the building or module conforms with the deformation-resistance test provided in CSA Z240.2.1. to confirm compliance with site-specific requirements  

CHBA's  "Working with Modular" Webinar Series

“Working with Modular” is a six-part webinar series highlighting the features and benefits of modular construction. The content is designed to inform on-site builders and developers, code officials, municipal planners and housing specialists, government departments, lenders, warranty providers and other stakeholders engaged in the residential construction industry. We would like to acknowledge the support of the Canada Mortgage and Housing Corporation in the development of the webinar series as well as Altus Group for their work in the project.

To watch the videos in full-screen mode, click on the YouTube icon in the bottom right of the video after you hit play.

Code Compliance for Modular Construction
(January 26, 2023) 


This webinar is predominantly aimed at building officials as it will describe how codes compliance is verified for factory-constructed buildings including provincial variations. The webinar will also explain how the factory certification according to CSA A277 works and what that means for code officials.



For more information contact: 


Frank Lohmann

Building Science
613-230-3060 ext. 231
[email protected]