Why a new floor squeaks, cups or gaps.

Why is my new floor creaking or squeaking, and is that normal?

Squeaking is almost always the subfloor moving against its framing or against its fasteners, not the new floor itself. The guidelines say that to minimise squeaks, subfloor panels should be glued and nailed to the floor framing.[1] A floor laid over a subfloor that was only nailed will often talk, and the new surface gets the blame.

The guidelines point specifically at APA Technical Note C468, Floor Squeaks: Causes, Solutions and Prevention, for addressing noise, and note that where the subfloor cannot be brought up to standard, replacing it or adding a second layer is what is required.[1] That is why the unglamorous part of a quote, screwing down and planing a subfloor, is the part worth paying for.

A little sound in the first weeks as fasteners seat is common. A squeak that gets worse, or one you can feel underfoot, is a subfloor problem and it does not fix itself.

Why is my hardwood floor cupping?

Cupping means the edges of each board are higher than the middle, and it means the underside of the wood is wetter than the top. Wood takes on and gives off moisture from the air around it, so cupping is a moisture reading, not a defect in the boards. Find the water before you touch the floor.

The guidelines list standing water as causing cracks, splits, cupping, warping and degradation of the finish, and they treat water damage as varying in severity from minor cupping through to severe buckling, with each case judged individually for repair.[1]

Common sources in a Southern Ontario house: a crawlspace or basement with no vapour control, a dishwasher or fridge line that has been weeping quietly, or a slab that was never moisture-tested before the floor went down. Sanding a cupped floor flat while it is still wet will crown it once it dries, which is a second repair on top of the first.

Are gaps in hardwood floors normal, and can they be fixed?

Seasonal gaps in solid wood are normal and are not a defect. Wood shrinks as the air dries. The guidelines define appropriate interior conditions for solid wood as 30% to 50% relative humidity and 60 to 80°F.[1] An Ontario house in February sits well under that, so boards pull apart and close again in July.

The fix for seasonal gaps is humidity, not carpentry. Filling them in winter means the filler is crushed or pushed out in summer when the boards swell back. Gaps that stay open all year, or that appear in only one part of a room, are a different problem and worth looking at properly.

Do new hardwood floors need time to settle?

What actually matters is not time, it is moisture content. The guidelines are explicit that an installer must know the ambient conditions in the room, the moisture content of the flooring, and the moisture content of the substrate.[1] Leaving boxes in a room for a week proves nothing if nobody measured anything.

On the subfloor side, the guidelines state that during the humid season wood subflooring should not exceed 13% moisture content, and that in regions that sustain higher levels, extra precautions belong in the product selection and the installation method.[1] Hardwood is manufactured at 6 to 9% moisture content with an allowance for pieces up to 12%.[1]

Max's take: the meter comes out before anything comes off the truck. A week of acclimation in a house that is running at 20% humidity is a week of the floor getting drier, not readier.

Why is my vinyl plank or laminate floor lifting, bouncy or separating at the seams?

A floating floor is one large panel that has to be free to move. When it lifts, peaks or opens at the seams, it is nearly always because it was pinched somewhere, or because the floor underneath it was not flat enough, or because the room got much hotter or colder than the product allows.

The flatness numbers are the same ones that govern glue-down wood, and they are tighter than most people expect: for glue-down and for fasteners under 1½", the subfloor should be flat to within 1/8" in 6', or 3/16" in 10'.[1] A hollow under a click floor becomes a deflection, and a deflection becomes a broken locking edge.

Pinch points to look for: baseboard or trim screwed down through the floor, a heavy island or bookcase sitting on it, or a doorway with no expansion gap. Your product's own instructions set the required gap and the maximum run before a transition is needed, and they override any general figure. More on the vinyl plank and laminate pages.

What happens if vinyl plank flooring gets wet underneath?

The plank itself may be waterproof. The space under it is not. Water that gets beneath a floating vinyl floor has nowhere to evaporate to, so it sits on the subfloor. On wood that means swelling and eventually mould; on concrete it means a moisture problem the floor is now sealing in.

This is why a slab has to be tested rather than assumed. The recognised methods are in-slab relative humidity probes to ASTM F2170, calcium chloride to ASTM F1869, or calcium carbide testing.[1] There is also a field check worth knowing: the guidelines suggest placing a drop of water on the concrete, and if it beads up the slab may carry a sealer or a waxy substance.[1]

A one-off spill wiped up quickly is not the issue. A slow leak under a waterproof floor is, precisely because nothing shows on the surface until it is bad.

How do you fix squeaky floors under carpet before the new floor goes down?

With the carpet up you can see the subfloor, which is the only time fixing it is cheap. The work is screwing the panels down into the joists, planing or levelling the high and low spots, and replacing anything soft or delaminated. This is the moment to do it, because it is buried afterwards.

The guidelines set the target: for nail-down installs with fasteners 1½" and longer, flat to within 3/16" in 6', or ¼" in 10'.[1] Where a subfloor cannot be brought to that, the guidelines call for replacement or a double-layer system rather than working over it.[1]

See what is included in subfloor prep for what that involves on an actual job.