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Code answers you can verify
Codebook Carl is a search tool for Canadian building and fire codes, built for the people who work with them every day — fire alarm technicians, inspectors, engineers, building officials, contractors, and property managers. Ask a question in plain language and Carl finds the governing clause in the actual code text, answers from it, and cites the exact document, section, and page so you can verify every claim against the source.
What's in the library
Carl searches a fixed library of Canadian codes and standards: the Ontario Building Code 2024 (both volumes), the National Building Code of Canada 2025, the Ontario Fire Code, and the core ULC fire alarm standards — CAN/ULC-S524 (installation), CAN/ULC-S527 (control units), CAN/ULC-S536 (inspection and testing), and CAN/ULC-S537 (verification). Answers come only from these documents — no outside knowledge, no guessing.
Which document governs your question?
Half the difficulty of code work is knowing which document holds the answer. The building code decides when a fire alarm system is required; S524 governs how it's installed; S537 governs the acceptance verification; and the Fire Code together with S536 govern testing for the life of the building. Carl works that out for you on every question — and if you want to understand the landscape yourself, start with our guide on how the codes and standards fit together.
Learn more
Browse the code and standards guides for plain-language explainers on each document, read industry articles, or learn more about how Carl works. Carl's answers are for general reference only — always verify against the full source documents and consult qualified professionals and the authority having jurisdiction before making compliance decisions.