Engineered floor systems and prefabricated trusses are standard building systems in residential construction across Ontario. Their use is well supported by the Ontario Building Code through their respective compliance pathways, including Part 9 and Part 4 design, CCMC evaluations, and manufacturer installation requirements. While these systems introduce efficiency and consistency into construction, they also introduce a layered design process that can blur lines of responsibility.

At a high level, the division of design responsibility appears straightforward. The building designer is responsible for the overall structural design of the building, including load paths, supports, and system performance. At the same time, the engineered floor or truss supplier is responsible for the design of individual components. For trusses in particular, this distinction is reinforced through the TPIC standard, which limits the truss designer’s role to the design of the truss elements themselves, while leaving support conditions, anchorage, and permanent bracing to the building designer.

In practice, however, this clear division becomes less obvious when considering the layout drawing. The layout drawing, typically prepared by the engineered floor or truss supplier, serves as the bridge between the building design and the individual engineered components. It illustrates the location and spacing of members, identifies hangers and other structural connectors, and indicates how the system is intended to be assembled within the building. 

Despite its importance, this drawing is frequently submitted without a professional seal, signature, or any clear indication of responsibility.

This creates a gap that doesn’t fit within the framework of the Building Code Act and the Ontario Building Code. The Act requires that any individual preparing drawings or providing an opinion on Code compliance is appropriately qualified to do so. At the same time, the Code requires that where design activities are undertaken and submitted as part of a permit application, there must be a clearly identified individual who has reviewed and taken responsibility for that work, supported by their qualifications and signature. When a layout drawing is submitted without this level of accountability, it becomes unclear who is taking responsibility for the design decisions embedded within it. 

The challenge is that this document does not sit neatly within the responsibilities of either party. It is not purely a component design, as it must align with building geometry, load paths, and support conditions. At the same time, it is not always prepared by the building designer, particularly where suppliers provide layout services as part of their package. The result is an “in-between” document that carries design implications but often lacks a designer of record.

Some jurisdictions have attempted to address this gap by using review or attestation forms. These forms ask the building designer to confirm that the layout has been reviewed and coordinated with their design, effectively assigning responsibility after the fact. While this approach can provide a level of assurance, it is not explicitly grounded in the Building Code Act and may be of concern when relied upon as a primary compliance strategy. As outlined in many attestation forms, the intent is for the designer to acknowledge coordination between the layout and the overall building design, but this does not replace the need for clear design responsibility at the outset.

A more consistent and defensible approach is to recognize the layout drawing as a design document. Where it influences member selection, load transfer, or system configuration, it must fall under the responsibility of a qualified designer. This responsibility can be fulfilled either by the building designer directly or by another qualified designer reviewing and taking ownership of the layout prepared by the supplier.

For building officials, this issue often becomes most apparent during permit review. Layout drawings that appear complete and detailed may still lack a clear designer of record. In these cases, the plans review includes not only whether the system has been correctly designed, but whether a qualified designer has taken responsibility for the coordination between the building design and the engineered components. Without that confirmation, the design remains noncompliant.

As engineered systems continue to evolve and the industry becomes increasingly specialized, these types of gaps are likely to become more common. Addressing them requires a consistent interpretation of the Building Code Act’s fundamental principle: that all design must be attributable to a qualified individual. Engineered floor and truss layouts are no exception. 

Applying that principle in practice means knowing what a framing package should contain and who is accountable for each part of it. Our upcoming Wall, Floor and Roof Framing live training course covers the individual assemblies, the load path that connects them, and the documentation required to support both.

The course covers:

• Wall framing — stud sizing, spacing and height limits, bearing versus non-bearing walls, lintels and headers over openings, built-up posts and point-load transfer, notching and drilling limits, lateral support and braced wall construction, and the point at which a tall or heavily loaded wall leaves the prescriptive tables behind.
• Floor framing — joist and beam span tables, engineered I-joists and open-web systems, bearing lengths, cantilevers, framed openings, hangers and connectors, squash blocks and web stiffeners, permitted web penetrations, blocking and bridging, and the fire protection requirements that apply to lightweight floor assemblies.
• Roof framing — rafters, ceiling joists and collar ties, prefabricated and girder trusses, support and anchorage, uplift resistance, permanent versus temporary bracing, hip and valley conditions, and cathedral and vaulted assemblies.
• Load path and lateral resistance — carrying gravity and lateral loads from roof to footing without a break, including snow, wind and unbalanced load conditions.
• Part 9 versus Part 4 — recognizing the trigger points where prescriptive framing ends and engineered design begins, and what has to be submitted when it does.
• Documentation and review — reading and checking supplier shop drawings and layout drawings, CCMC evaluation reports and manufacturer installation requirements, designer of record and qualification requirements, and the deficiencies that most often show up in plans review.

This one day course uses worked examples and plan review scenarios rather than a straight read of the Code. It is built for building officials, designers, builders and suppliers, since all four have a part in how a framing package comes together.