How much does subfloor replacement cost in New Brunswick?

Subfloor replacement in New Brunswick typically runs $3–$8 per square foot for materials and labour combined, though full-room projects can push higher depending on what's underneath. A 200 sq ft bedroom might cost $600–$1,600, while a larger main floor could easily reach $4,000–$8,000+ once you factor in flooring removal and reinstallation.

The spread is wide because subfloor jobs are notorious for surprises. What starts as "replace a soft spot near the toilet" often turns into a conversation about joists, moisture damage, or rot that's been spreading for years. In older NB homes — particularly the post-war bungalows common in Moncton, Oromocto, and Saint John, or the Victorian-era homes in Fredericton's north end — you may be looking at original 1×6 board subfloor over joists that have seen decades of humidity cycling. Replacing it with modern 3/4" tongue-and-groove OSB or plywood is a genuine upgrade, but the labour to demo the old material adds up fast.

What drives the price up or down:

• Material choice: 3/4" tongue-and-groove OSB runs $40–$55 per sheet; premium plywood (preferred in wet areas) is $60–$80+. A 200 sq ft room needs roughly 12–14 sheets.
• Extent of damage: Spot repairs (a few sheets) are cheaper per square foot than full-room replacement
• Joist condition: If your contractor pulls up the subfloor and finds soft or damaged joists, expect an additional $50–$150+ per joist for sistering or replacement
• Bathroom/kitchen premiums: Moisture-related subfloor damage in wet rooms adds complexity — waterproofing membrane, cement board in tile areas, and sometimes drain relocation all factor in
• Access and existing flooring: Tile removal costs $1–$3/sq ft extra; hardwood removal and reinstallation can add $3–$6/sq ft on top

A realistic breakdown for a mid-size bathroom (80 sq ft) with moderate moisture damage:

• Subfloor removal and disposal: $200–$400
• New 3/4" plywood and fasteners: $250–$400
• Labour to install: $300–$600
• Cement board for tile base: $150–$250
• Total before new flooring: $900–$1,650

This is genuinely DIY-accessible work for someone comfortable with a circular saw and impact driver — cutting and fastening sheet goods isn't complicated. That said, correctly diagnosing why the subfloor failed in the first place is where most homeowners get into trouble. If there's an active moisture source (slow leak, condensation, inadequate vapour barrier), replacing the subfloor without fixing the root cause means you'll be doing it again in five years.

New Brunswick's climate adds a layer of consideration here. High water tables across much of the province — especially in Riverview, Quispamsis, and the river valley communities — mean basement and ground-floor subfloor moisture issues are extremely common. If you're seeing soft spots along exterior walls or near the perimeter, it's worth having a contractor assess whether the issue is coming up from below rather than down from above.

No building permit is required for subfloor replacement alone (it's not structural), but if the work involves plumbing changes — say, relocating a toilet flange — that requires a licensed plumber and a permit through NB Dept. of Justice and Public Safety Technical Inspection Services (TIS) at 1-888-659-3222.

Your best next step is to get two or three quotes from local flooring or general contractors who can actually lift a corner and assess the joist condition before pricing the job. Browse the New Brunswick Construction Network directory to find contractors in your area — and make sure to ask each one specifically whether they'll inspect the joists as part of the quote, not just the subfloor itself.