What a "Letter of Assurance" Is (and Where It's Used)

A letter of assurance is a formal document, most associated with jurisdictions like British Columbia, where a registered professional — an engineer or architect — certifies that specific aspects of a design or the completed construction meet code, taking on professional and legal responsibility for that certification. It shifts part of the compliance-verification burden from the building department onto a licensed professional.

The system generally uses different letters at different stages: one at permit application confirming the design meets code, and another at project completion confirming construction matches what was designed. It speeds up permit review for complex projects, since the building department can rely on the professional's certification rather than independently re-verifying every calculation.