What causes laminate flooring to develop white lines or gaps at the seams in NB homes during winter?

White lines or gaps appearing at laminate seams during winter are caused by the planks shrinking as your home's heated air drops indoor humidity to extremely dry levels — a particularly severe problem in New Brunswick's Maritime climate.

During NB's heating season (October through April), forced-air heating systems drop indoor relative humidity to 20-30%, well below the 35-55% range that keeps building materials dimensionally stable. While laminate flooring is more stable than solid hardwood, the high-density fiberboard (HDF) core in most laminate products still contains wood fibers that respond to moisture changes. As these fibers lose moisture in your home's dry winter air, the planks contract slightly, creating visible gaps at the click-lock seams that appear as thin white or light-colored lines.

New Brunswick's winter drying is more extreme than most Canadian provinces because Maritime homes experience dramatic humidity swings — from 65%+ relative humidity in summer down to 20-25% in winter. This 40-50% swing stresses any wood-based flooring product. Coastal NB communities (Saint John, Shediac, Bathurst) may see less severe gapping because ambient humidity stays higher, but inland areas like Fredericton, Woodstock, and Miramichi commonly experience the most dramatic shrinkage.

The white appearance comes from the light-colored substrate or underlayment showing through the gaps, contrasting with the darker laminate surface. These gaps typically close when humidity returns in spring, but repeated seasonal cycling can stress the click-lock connections and eventually cause permanent separation or damage to the locking mechanism.

Prevent winter gapping by maintaining 35-45% relative humidity with a whole-home humidifier or portable units in rooms with laminate flooring. Monitor humidity levels with a digital hygrometer ($15-30) and run humidifiers consistently during heating season. If gaps have already appeared, avoid trying to push planks back together — this can damage the click-lock system. Instead, focus on humidity control and allow the planks to naturally expand back together as moisture returns.

Choose water-resistant or waterproof core laminate (WPC or SPC cores instead of standard HDF) for future installations in NB homes. These products use polymer cores that don't respond to humidity changes, eliminating seasonal gapping entirely while providing superior moisture resistance for Maritime conditions.

Need help finding a professional flooring installer who understands NB's humidity challenges? New Brunswick Flooring can match you with local contractors experienced in moisture-stable flooring solutions.