Read the Symptom, Then Find the Cause
The most expensive mistake in hardwood repair is treating the symptom. Replacing cupped boards while the crawlspace is still damp, or sanding a floor that is still moving, guarantees doing the work twice.
Here are the seven things we get called about most, what each one means, and how urgent it is.
1. Cupping — Edges Higher Than Centres
What it looks like: run your hand across the boards and the edges feel raised. In strong light, the floor looks slightly corrugated.
What it means: the underside of the wood is wetter than the top. Moisture is coming from below — a crawlspace, a basement, a slow plumbing leak — or the room’s humidity is high.
Urgency: high, but not for the floor. Find the water. A cupped floor often flattens substantially once the moisture source is resolved and the wood re-equilibrates, and sanding it before that happens produces crowning later, where the centres end up proud of the edges.
2. Gaps Between Boards
What it looks like: visible lines between boards, worst in winter.
What it means: in Calgary, usually nothing. Furnace heat dries indoor air, the wood loses moisture and shrinks, and the gaps close again in summer. It is seasonal behaviour, not damage.
When to worry: gaps wide enough to catch a coin, gaps that do not close in summer, or gaps accompanied by cracked or separated boards. Those suggest wood installed at the wrong moisture content, or a home running far below the humidity range the manufacturer specifies.
Urgency: low, unless permanent. A furnace humidifier is usually the fix — see our hardwood flooring page for the ranges involved.
3. Grey or Dull Traffic Lanes
What it looks like: a visible path through the room where the floor has lost its sheen and looks cloudy or grey.
What it means: the finish has worn through, and the bare wood is exposed and oxidizing. The wood itself is usually still sound.
Urgency: moderate, and rising. While it is only the finish, a screen-and-recoat or a full sand and refinish restores the floor completely. Once dirt and moisture have worked into the open grain, the repair becomes more involved and the results less perfect. Our floor refinishing page explains both options.
4. Black Stains
What it looks like: dark patches, often around pet areas, near doors, or under where a plant pot sat.
What it means: water or urine has penetrated the finish and reacted with the wood. This is not surface dirt.
Urgency: moderate. It will not spread quickly, but it will not sand out either. The affected boards are cut out and new ones woven in, matching species, width and thickness, then the area is refinished so the repair disappears. If the liquid reached the subfloor, that needs treating too.
5. Squeaks Underfoot
What it looks like: you can walk the same path every day and hear the same two boards.
What it means: movement. Either the flooring is loose against the subfloor, or the subfloor has loosened from the joists as framing dried over the years — extremely common in Calgary homes over twenty years old.
Urgency: low for the floor, high for your patience. It is usually a straightforward repair, and the ideal time to do it is while flooring is being replaced or refinished anyway. Our subfloor repair page covers the methods.
6. Hollow or Loose Boards
What it looks like: a board flexes or clicks when you step on it, or sounds hollow when tapped.
What it means: the board has lost its fastening or, in a glued floor, its bond. Left alone, it works against its neighbours and damages the tongue and groove.
Urgency: moderate. Re-securing one loose board is minor work. Waiting until the joint is chewed up means replacing several.
7. Buckling — Boards Lifting Off the Subfloor
What it looks like: a section of floor visibly raised off the subfloor, sometimes tenting.
What it means: either significant water exposure, or a floor with no room to expand — expansion gaps skipped at installation, or trim nailed through the floor pinning it in place.
Urgency: high. Buckling usually means removal of the affected area, resolving the cause, and reinstatement. It does not self-correct.
The Question Behind All Seven
For every symptom above, the same two questions decide the repair: what caused it, and is the cause still active?
A floor that has stopped moving can be repaired and refinished with confidence. A floor that is still reacting to a leak, a damp basement or a home running at 15% humidity will simply do it again.
That is why our first visit for any wood-floor problem is diagnostic: moisture readings where relevant, a look at what is below the floor, and a straight answer about whether to act now or fix the cause first.
Timing Matters in a Dry Climate
When you act on a wood-floor problem is almost as important as what you do, and Calgary’s seasons push in a specific direction.
Gaps look worst in late winter. By February, indoor humidity has been low for months and boards are at their most contracted. That is the wrong moment to judge whether gaps are permanent, and a poor moment to fill them — filler placed while the floor is fully shrunk gets compressed when the wood expands again in summer.
Cupping should be assessed after drying, not during. A floor reacting to a resolved leak can flatten significantly on its own over weeks. Sanding it while it is still cupped produces crowning later, when the edges drop back and the centres stand proud.
Refinishing is easier in shoulder seasons. Spring and autumn give moderate indoor humidity and the option of ventilation without heating the outdoors, which suits finish curing.
Water damage is the exception. That is urgent regardless of season. The longer wood stays wet, the less of it can be saved, and the more likely the subfloor beneath needs attention too.
The general principle: for moisture-related symptoms, find and fix the cause first, let the floor stabilize, then repair. For wear-related symptoms, act while the damage is still in the finish rather than in the wood.
Repair, Refinish or Replace?
- Finish damage only: screen and recoat, or full refinish.
- A handful of damaged or stained boards: board replacement plus refinishing.
- Squeaks with a sound floor: re-fastening, no replacement.
- Cupping after a resolved leak: dry, stabilize, then reassess.
- Buckling or damage across most of a room: replacement.
Our hardwood floor repair page covers the techniques, and if you would rather have someone look at it, a free estimate includes the diagnosis — with no deposit and no obligation.