Existing building: when does renovation trigger an upgrade?

Avoid both opposite errors: assuming everything must meet today’s code or assuming every old condition is automatically grandfathered.

VERT / GREEN

Identify the exact altered portion, use and jurisdiction.

JAUNE / YELLOW

Addition, reconstruction, occupancy change or affected systems can broaden requirements.

ROUGE / RED

Application to existing buildings depends on the adopted code and authority; do not generate a universal grandfathering rule.

Project triage

Like-for-like repair
Still verify local or safety requirements. Portion reconstructed/altered
Identify which current requirements apply to the affected portion. Change of use/occupancy
Confirm triggered requirements before finalizing design. Grandfathering question
Seek a written answer from the authority rather than assuming.

What the professional checks

The designer and authority determine applicable scope based on building, work, occupancy and adopted regulation.

Official sources

CNRC — Code national du bâtiment 2025

Vérifié / checked: 2026-08-23

Explore: Systems to check before closing the work

Systems to check before closing the work

This section connects envelope, air, fire, structure, water and code instead of treating each project in isolation.

Renovation dependenciesRenovating while living at homeCode versions

Explore: Finish and service details to verify

Finish and service details to verify

This section connects small details that become costly once finishes are closed.

Post-renovation cleaning and indoor air