What fire code separation is required between a garden suite and the main house in Moncton's new zoning?

Garden suites in Moncton now require a minimum 45-minute fire separation between the suite and the main dwelling — and if the structures are attached or share a wall, that requirement steps up significantly under the National Building Code of Canada 2020, which New Brunswick adopted effective May 1, 2025.

Here's how it breaks down in practice. A detached garden suite (a fully separate structure on the same lot) has the most flexibility — as long as it maintains the required setbacks from the main house, the two buildings are treated as separate structures and the fire separation requirement between them is essentially managed through spatial separation rather than rated assemblies. The NBC 2020 sets out limiting distance calculations that determine how much unprotected opening area is permitted in exterior walls based on how far apart the buildings sit. In a typical Moncton residential lot, you're often working with tight setbacks, which means exterior walls facing the main house may need to be constructed with a 45-minute fire-resistance rating and limited or no unprotected openings (windows, doors) on that exposure.

If the garden suite is attached to the main house — sharing a wall, connected by a breezeway, or built above a garage — the fire separation requirement between the two dwelling units jumps to a minimum 45-minute fire-resistance rating for the separating assembly, with many configurations requiring a full 1-hour fire-rated wall and floor assembly. This is standard for any two-unit residential building under NBC Part 9.

A few other fire-related requirements that go hand-in-hand with the separation:

• Interconnected smoke alarms are required in both units — not just battery-operated standalone units, but hardwired with battery backup and interconnection between the suite and the main house
• Carbon monoxide detectors are required in both units if either has a fuel-burning appliance or attached garage
• Egress windows in any bedroom of the garden suite must meet NBC minimums (0.35 m² clear opening, no dimension less than 380mm)
• Separate entrance is required for the garden suite

On the Moncton zoning side specifically, the City of Moncton updated its zoning bylaw to permit garden suites (also called secondary suites and accessory dwelling units) in most residential zones. You'll want to confirm your specific zone and lot coverage limits directly with Moncton Planning & Development at (506) 856-4375 or info.plans@moncton.ca — setback requirements, maximum suite size, and lot coverage rules all affect what's buildable on your specific property.

The building permit comes from the City of Moncton, and the fire separation details will be reviewed as part of that permit application. Your contractor will need to submit plans showing the wall assembly specifications — don't leave this to a verbal agreement with a builder. Get it in writing and in the drawings.

For the actual construction, this is firmly in licensed-contractor territory. The fire-rated assemblies need to be built correctly — the right drywall type (Type X), proper fastening patterns, no penetrations without fire-stopping — and a building inspector will verify compliance before occupancy. A mistake here isn't just a code violation; it's a life-safety issue.

Browse licensed contractors experienced with secondary suites and garden suites in the New Brunswick Construction Network directory — finding someone who's built these before in Moncton will save you a lot of back-and-forth with the permit office.