How do I fix squeaky subfloors before installing new carpet in my NB home?

Squeaky subfloors are caused by movement between the subfloor panel and the floor joists, and the best time to fix them is before new carpet goes down — once carpet is installed, repairs become far more difficult and disruptive. In New Brunswick's older housing stock, subfloor squeaks are extremely common and typically worsen with the province's seasonal humidity cycles.

The squeak itself comes from either nails that have worked loose from the joist (the nail slides up and down in the wood as you walk, creating the noise) or subfloor panels that have slight gaps above the joist (the panel flexes downward under your weight and rubs against the nail or adjacent panel). NB's dramatic indoor humidity swings — from 20–30% in winter to 60%+ in summer — cause wood subfloors to expand and contract annually, gradually loosening the original nails and creating these gaps over decades.

Fixing squeaks from above (the most practical approach when carpet is being replaced):

First, locate each squeak precisely by walking the entire floor systematically and marking squeaky spots with painter's tape. Have a helper stand below in the basement or crawl space to confirm which joist the squeak sits near. In NB homes with finished basement ceilings, you'll need to work entirely from above.

Drive screws — not nails — through the subfloor into the joists at each squeak location. Use #8 or #10 wood screws, 2 to 2.5 inches long (adjust length to penetrate the subfloor thickness plus at least 1 inch into the joist without poking through the ceiling below). Screws pull the subfloor tightly against the joist and hold far better than nails in NB's cycling humidity conditions. Pre-drill pilot holes to prevent splitting, especially in older, drier subfloor panels. Place screws 6–8 inches apart along the joist in problem areas, and countersink the screw heads slightly below the subfloor surface so they don't create bumps under the new carpet.

For widespread squeaks across an older NB home, re-screw the entire subfloor to every joist at 8-inch intervals. This is the nuclear option but eliminates future squeaks comprehensively. It takes a full day for a typical main floor and costs roughly $1–$2/sq ft in labour if you hire a professional, or just the cost of screws ($50–$100 in materials) if you do it yourself.

Fixing squeaks from below (if you have access to exposed joists in the basement):

Have someone walk on the squeaky spot while you watch from below. If you can see the subfloor panel flexing away from the joist, apply construction adhesive (PL Premium or similar) along the joist-to-subfloor joint and drive a short screw at an angle through the joist into the subfloor to pull it tight. For gaps between the joist and subfloor, tap a wood shim coated in construction adhesive into the gap to eliminate the movement.

NB-specific subfloor considerations: Many pre-1970s NB homes have board subfloors (individual planks rather than plywood sheets) that are more prone to squeaks and movement. Board subfloors often need a 3/8 or 1/2 inch plywood overlay ($1.50–$3.00/sq ft materials plus labour) screwed over the boards to create a stable, flat surface for new carpet. This overlay also eliminates most squeaks by locking the boards in place. Homes in river valley areas like Fredericton and Miramichi, or coastal communities with high ambient humidity, tend to have more subfloor movement and squeaking than homes in drier inland locations.

This is a solid DIY project for handy homeowners with a drill and basic skills. However, if your subfloor has soft spots, significant unevenness, or visible damage, consult a professional before installing new flooring — these may indicate joist or structural issues that go beyond a simple squeak fix.

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

• Gionetterenovations
• First united design & construction inc.
• The Garbage Guys Ltd
• RenoMe
• Thirty Four Renovations