Do I need a permit for subfloor structural repair in my NB home?

Yes, if your subfloor repair involves cutting, modifying, or reinforcing floor joists or other structural members, you will need a building permit in New Brunswick. Simply replacing plywood or OSB sheathing on top of existing joists does not require a permit, but anything that affects the structural integrity of the floor assembly does.

The distinction comes down to whether you are replacing a surface or altering a structure. Pulling up damaged plywood subflooring and screwing down new 3/4-inch tongue-and-groove plywood or OSB over sound joists is considered a repair to the floor covering system — no permit needed. However, the moment you need to sister a cracked joist, add a beam or post for sagging floor support, cut into joists for plumbing or mechanical runs, or replace sections of the joist system itself, you are performing structural work that requires a building permit and inspection. In New Brunswick, you apply for your permit through your municipal building inspection office if you live in an incorporated city or town (Moncton, Saint John, Fredericton, Bathurst, Miramichi, etc.) or through the local Rural Service Commission if your property is in an unincorporated area.

Permit fees for structural repair in NB are typically modest — often $50 to $200 for residential work depending on the municipality — but the inspection that comes with the permit is where the real value lies. An inspector verifies that repairs meet the National Building Code as adopted by New Brunswick, ensuring your floor can safely carry the loads it was designed for.

NB housing stock makes this especially relevant. Many New Brunswick homes built before the 1960s have original subfloor assemblies using 1-inch board sheathing laid diagonally over dimensional lumber joists. Decades of Maritime humidity cycling, occasional basement moisture intrusion during spring snowmelt, and the freeze-thaw stress that NB's 100-plus annual cycles impose on foundations and crawl spaces mean that structural subfloor damage is more common here than in drier provinces. Sagging floors, bouncy spots, and visible joist damage are frequent findings in older Moncton, Saint John, and Fredericton homes.

Before starting any subfloor repair, inspect the joists carefully from below. Look for cracks, rot (especially near the sill plate where moisture wicks up from the foundation), insect damage, and excessive notching from old plumbing or wiring. If the joists are sound and level, you likely just need new sheathing — a straightforward job at roughly $1.50 to $3.00 per square foot for materials plus labour. If the joists need repair, expect to spend $500 to $2,000 or more depending on the extent of the work, and budget for the permit and inspection process.

When in doubt, hire a professional. A licensed contractor experienced with NB's older housing stock can assess whether your subfloor issue is cosmetic or structural, pull the permit if needed, and ensure repairs are done to code. This is especially important if you are planning to install new flooring on top — hardwood, tile, and even LVP will telegraph subfloor problems if the underlying structure is not sound. Getting this right before the new floor goes down saves thousands in potential rework.

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Looking for experienced contractors? The New Brunswick Construction Network connects homeowners with qualified professionals:

• Arctic Fox Construction Inc.
• Thirty Four Renovations
• The Garbage Guys Ltd
• RenoMe
• First united design & construction inc.