Winter Gapping in a Floating Engineered Plank Floor

The gaps are seasonal shrinkage, not a product defect.

• Wood flooring moves with indoor humidity. The planks went from a summer environment near 52% RH to winter conditions at 16–20% RH. Equilibrium moisture content at 72°F and 20% RH is roughly 4–5%, which matches the meter reading of 5–6%.
• As the planks lose moisture, they shrink across their width. On a 7-inch-wide engineered plank, cumulative shrinkage across many boards produces visible gaps of 1/8 to 3/16 inch, especially at end joints.
• The homeowner's report that gaps close in summer is a strong diagnostic sign of reversible moisture movement.
• A product defect would typically produce delamination, inconsistent plank dimensions, or finish failures, not uniform seasonal gaps that reverse with humidity. The absence of cupping and the flat, quiet floor further argue against a manufacturing problem.

The report should classify the condition as normal seasonal movement under low winter humidity, not a defect claim.

Seasonal movement and installation restraint look different when mapped carefully.

• Map every gap by location, width, and direction. Seasonal shrinkage is usually distributed across the field and widest near dry-air sources such as registers and sliding doors. Installation-related gaps tend to concentrate at restraints or at the ends of long runs.
• Check the perimeter and penetrations. The tight jamb is a genuine restraint point. If the floor were binding there, you would expect compression, squeaks, or buckling near that doorway - not an absence of gaps. The fact that no gapping appears in that immediate area is consistent with restraint, but it must be evaluated against the rest of the floor.
• Verify the humidity history with a data logger or utility records. A clear correlation between low RH and gap width supports seasonal movement.
• Confirm moisture content at several points and compare to equilibrium. Uniform 5–6% readings across the field fit dry indoor air; isolated wet or dry spots suggest a different problem.
• Look for other installation errors: insufficient underlayment, wrong acclimation, or a floor installed tight to walls elsewhere. A single tight jamb does not explain gaps across the whole floor.

In this case, the distributed gap pattern, the summer closure, and the uniform low moisture readings point to seasonal movement. The jamb is a separate correction item.

Recommendations should address both the environment and the restraint point.

Homeowner

• Maintain indoor RH between roughly 35% and 55% year-round with a humidifier in winter and dehumidification in summer.
• Do not fill the gaps now. Filling during the dry season can cause buckling when the floor expands in summer.
• Monitor gap width and indoor RH for a full heating season before considering any repair.

Installer

• Relieve the tight jamb by undercutting or trimming so the plank has the specified clearance.
• Verify perimeter expansion at all walls, cabinets, and thresholds.
• Document that the floor was installed within the manufacturer's acclimation and moisture specifications.

Inspector's conclusion

• The gapping is consistent with low winter humidity and reversible seasonal movement, not a manufacturing defect.
• The tight jamb is a localized installation issue that should be corrected, but it is not the cause of the field-wide gaps.
• If the homeowner wants the gaps reduced, the effective remedy is humidity control, not replacing the floor.