Most hardwood floor complaints in the first two years are not defects in the wood. They are installation problems, and nearly all of them trace back to the same two causes: the wood was not acclimated properly, or the subfloor was not prepared properly.
The difficulty is that hardwood moves seasonally on its own, so not everything that looks wrong is wrong. Here is how to tell the difference, and what can still be corrected.
First: What Is Normal
Before calling anything a defect, rule these out.
- Seasonal gaps in winter. Solid hardwood contracts in dry heated air. Thin gaps that open in January and close by June are the wood behaving as designed. In Georgia this is common and expected.
- Slight color variation between boards. Wood is not manufactured to a color. Variation within a grade is normal and usually looks better over time as the floor evens out with UV exposure.
- Some sound. A quiet creak in a spot or two is not a failure. Continuous squeaking across a room usually means fasteners have worked loose and is worth a look.
- A new floor looking different from the sample. Species, grain, and light all change how a stain reads, which is frustrating but not an installation defect.
The Signs That Do Indicate a Problem
1. Gaps That Never Close
Seasonal gaps close in humid months. Gaps that stay open through a full year, or that vary wildly from one part of the room to another, mean the flooring was installed at the wrong moisture content. Wood delivered wet and installed immediately dries in place and shrinks, leaving permanent gaps.
The tell is consistency. Uniform thin gaps across a whole room in February are seasonal. Wide gaps in one area and tight boards in another are not.
2. Cupping
Board edges sitting higher than the centers, giving the floor a subtle washboard feel. Cupping means the underside of the boards is wetter than the top. Causes include installation over a damp subfloor, no vapor barrier over a crawl space or slab, or the wood being too dry when it went down and then absorbing moisture afterward.
Cupping that appears in the first year is almost always an installation or moisture-control failure. Cupping that appears in year eight usually means a new water source, worth investigating before any refinishing work covers it up.
3. Buckling or Lifting
Boards pulling away from the subfloor, or a section of floor rising into a ridge. On a floating floor this almost always means no expansion gap was left at the walls, so when the floor grew it had nowhere to go. On a nail-down floor it usually means a significant moisture event.
This is the most serious of the common problems and the one least likely to resolve on its own.
4. Hollow or Bouncy Spots
Areas that sound different underfoot or give slightly. On a glue-down floor this means the adhesive did not bond, often because the subfloor was dusty or not flat. On nail-down it can mean missed fasteners or a subfloor dip.
Walk the whole floor in socks and listen. A clear difference in sound between one area and the rest is worth flagging.
5. Uneven Board Heights, Called Overwood
Adjacent boards sitting at different heights, so you can feel an edge with a bare foot. Small amounts are normal on site-finished floors before sanding. On a prefinished floor there should be almost none, and where there is, it usually means the subfloor was not flat.
6. Visible Nails, Filler, or Splitting at the Ends
Face-nailing should be limited to the first and last rows where a nailer will not fit, and those nails should be set and filled. Widespread face nails, obvious filler, or boards split at the tongue mean the nailer was set wrong or the wood was brittle.
7. Poor Layout Decisions
- Boards running the wrong direction, usually across the joists rather than perpendicular to them, or across the room's length rather than along it
- Short offcut pieces clustered together rather than distributed, which reads as patchy
- End joints in adjacent rows falling too close to each other, creating an H pattern
- Thin ripped boards at a wall where the layout should have been balanced from the center
These are judgment failures rather than technical ones, and they are the hardest to argue about, but an experienced installer avoids all four.
8. Transitions and Trim Done Badly
Large gaps at the baseboard that shoe molding does not cover, transitions that are not level with either floor, or a missing expansion gap at a fixed obstacle like a hearth or an island. These are finishing details, and they are often the most visible part of a job.
The Two Root Causes
Nearly everything above comes back to one of these.
Acclimation
Wood needs to reach equilibrium with the house before it goes down. That means delivering it into the conditioned space, letting it sit for several days, and checking that the moisture content of the flooring is within a couple of percent of the subfloor.
An installer who delivers flooring and starts laying it the same day is skipping this. It is the single most common corner cut in the trade, because acclimation is days of waiting that nobody is paid for.
Subfloor Preparation
The subfloor needs to be flat within tolerance, dry within tolerance, clean, and structurally sound. Hardwood telegraphs every dip and every unfixed problem underneath. A subfloor that is out of flat by a quarter inch over ten feet produces a floor that feels wrong and eventually develops hollow spots.
How Long Acclimation Actually Takes
There is no single universal number, because the real target is a moisture content reading rather than a day count, but most solid hardwood needs a minimum of three to five days sitting in the conditioned space before it goes down, and wide plank or wood delivered in very different humidity conditions can need longer. What matters more than the day count is the measurement: the flooring and the subfloor should read within a couple of percentage points of each other on a moisture meter before installation starts. An installer who cannot tell you those readings has probably not taken them.
Filling Gaps Has Real Limits
Gap filling works, but only within a narrow range, and it is not the fix for everything this post covers. Narrow, uniform gaps left by normal wood movement can be filled with a color-matched wood filler or a flexible caulk product made for the purpose, and the repair holds because the gap is not going to change size dramatically again. Wide, uneven gaps caused by installing wood that was never properly acclimated are a different problem: filler in a gap that is still actively moving cracks out within a season or two, so the honest fix is usually replacing the affected boards rather than filling around a moisture problem that has not been resolved.
The Pre-Installation Checklist
If your installation has not started yet, confirm these before the first board goes down. Every one of them is a question an installer should be able to answer without hesitating.
- Has the flooring been acclimated in the conditioned space, and for how long?
- Has the moisture content of both the flooring and the subfloor been measured, and what were the readings?
- Is the HVAC running and the house at normal living conditions? Installing into an unconditioned house is a guaranteed problem.
- Has the subfloor been checked for flatness, and what is the plan if it is out of tolerance?
- Is there a vapor barrier where the assembly needs one, particularly over crawl spaces and slabs?
- What expansion gap is being left at walls and fixed obstacles?
- Which direction are the boards running, and why?
- Has the layout been planned from a center line so both edge rows are a reasonable width?
- Who is responsible if the subfloor needs work, and how will that be priced?
- What does the installation warranty cover, separate from the manufacturer's warranty on the wood?
Asking these does not make you a difficult customer. It makes you a customer who gets a floor that lasts.
What Can Be Fixed After the Fact
| Problem | Fixable? | How |
|---|---|---|
| Seasonal gaps | No fix needed | Manage indoor humidity between 35 and 55 percent |
| Permanent gaps | Partly | Filling works on narrow gaps. Wide ones need boards replaced or the floor relaid. |
| Mild cupping | Often | Fix the moisture source, let it dry fully, then sand flat. Sanding too early causes crowning. |
| Severe cupping or buckling | Rarely | Affected boards usually need replacing |
| Hollow spots | Sometimes | Injection on glue-down floors. Nail-down often needs boards lifted. |
| Overwood | Yes on site-finished | Sanding flat. Prefinished floors cannot be sanded without losing the factory finish. |
| Squeaks | Usually | Refastening from above or below |
| Layout problems | No | Direction and board placement cannot be corrected without relaying |
Our hardwood floor repair service handles most of the fixable column. If you are early enough that the floor has not gone down yet, our hardwood floor installation team is the better conversation.
An Early Look Is Worth It
Several of these problems get cheaper to correct the sooner they are caught. TriArt Hardwoods installs and repairs hardwood across Atlanta, Johns Creek, and Sandy Springs. Our hardwood floor repair page has more on what that process looks like, or our contact page can get an early look scheduled.
