Water Damage on Hardwood Floors in Montréal: Repair, Refinish, or Replace?
Cupping, crowning, black stains — a Montréal contractor decision tree for water-damaged hardwood: when to spot-repair, sand-and-refinish, or replace.
Water on a hardwood floor is a stopwatch. Within the first 24 hours, almost any damage is recoverable. Past 72 hours, the wood has cupped, the finish has lifted, and the subfloor below is starting to grow mould. Here's the decision tree a Montréal contractor uses on water-damaged hardwood, and the price ranges for each option.
The three damage signatures
- Cupping. The edges of each plank rise above the centre, creating ripples you can feel barefoot. Cause: moisture absorbed from below (slow leak, basement humidity, dishwasher drip). The wood swells unevenly and lifts at the seams.
- Crowning. The opposite — the centre of each plank rises above the edges. Cause: water from above (overflow, broken pipe) followed by a sand or aggressive drying before the moisture below caught up. Almost always preceded by cupping that was sanded flat too early.
- Black staining. Tannins in the wood react with moisture + metal (nails, water-supply pipes) to produce iron-tannate stains that don't sand out. Black streaks following plank seams, or radiating from a single point of impact (vase, planter, dog bowl).
The decision tree
Step 1: Has the source been stopped?
If water is still entering — leak, humidity, basement flooding — fix that first. Any repair done before the source is stopped will repeat. We will not quote a refinish job over an unfixed source.
Step 2: Measure subfloor moisture content
A pin-style moisture meter pressed against the underside of the floor (through a heat register cavity, or basement ceiling) tells us:
- Under 12% MC — wood is dry. Cosmetic damage only. Proceed to repair/refinish.
- 12–18% MC — wood is wet but recoverable. Dehumidify the space 7–14 days, re-test before any work.
- Over 18% MC — saturated. Open up the subfloor, dry mechanically, and re-evaluate after drying. Mould inspection recommended.
Step 3: Pick the right repair
| Damage | Repair | Typical cost (Montréal, 2026) |
|---|---|---|
| Light surface cupping, MC dry | Full sanding flattens it. Two-coat refinish. | Quoted on inspection |
| Localized black stains, fewer than 6 boards | Replace affected boards, blend stain, sand and refinish whole floor | Quoted on inspection |
| Localized cupping in one room | Spot-dry below, then full sanding when MC returns to normal | Quoted on inspection |
| Crowned floor (over-sanded after water damage) | Can usually be salvaged with a slow, careful sanding once equilibrium reached. 30% of cases require partial replacement. | Quoted on inspection |
| Buckled floor (lifted from subfloor) | Replace planks in the affected area. Subfloor inspection mandatory. | Quoted on inspection |
| Mould in subfloor | Full removal, subfloor replacement, then new finish flooring | Quoted on inspection |
Insurance claims — what to document
If the damage is from a covered event (burst pipe, appliance failure, upstairs leak), photograph everything before any work starts:
- Wide shots of each affected room
- Close-ups of cupping, staining, finish damage
- The water source, if visible
- Date-stamped readings from a moisture meter, if you have access to one
Get the repair quote in writing before insurance authorizes. Most carriers will pay our estimate directly with proper documentation.
