Laminate is made of a core material — typically high-density fiberboard or particle board — wrapped in a protective wear layer on top and a backing layer on the bottom. That core material swells when it is exposed to water and moisture. The swelling happens at cut edges and at joints where water sits instead of draining away cleanly. If water gets into those edges and stays there, the core swells, expands, and the floor can buckle or warp. That is not a defect in the floor; that is laminate behaving as its materials are inherently designed to behave when exposed to moisture. Understanding this fundamental behavior is the starting point for making an informed decision about laminate in wet spaces.
There is a significant difference between water-resistant and waterproof claims. Water-resistant means the product has been treated to resist water penetration but is not impervious — it can still fail if water exposure is prolonged. Waterproof means the material will not allow water through at all under normal conditions. Marketing language in the flooring industry often conflates or blurs these two different claims. A water-resistant laminate can still fail if water sits on it long enough or gets into the cut edges and joints. Truly waterproof laminates do exist but they are rare, expensive, and still require proper installation and edge sealing.
A two-piece powder room is a very different proposition than a main family bathroom with a shower. A powder room has no shower spray, minimal standing water, and only brief exposure to moisture from handwashing and toilet use. Laminate can work reasonably well in a powder room if all edges are sealed and the floor drains well. A main bathroom with a shower is a wet room with constant steam, splash, and standing water collection around the shower base. Laminate is at significant risk in that environment, particularly around the shower enclosure where standing water collects and edges are vulnerable to prolonged saturation. The practical difference between these two applications is enormous and should drive the material choice.
Edge sealing is what determines whether a laminate floor survives or fails prematurely in any bathroom application. A wax-sealed edge that keeps water out is the critical difference between a floor that lasts many years and one that fails after a year or two. Perimeter sealing at the walls is equally important, so water does not run between the floor and the baseboard. That sealing has to be maintained and monitored over time — any breakdown in the seal creates a path for water damage.