Water-Swollen Laminate and a Flatness Dispute
An 8 mm AC3 laminate was installed in a second-floor laundry room over a wood subfloor. A washing-machine supply hose leaked for about two days while the owners were away. The laminate now shows swollen edges and raised seams across roughly 120 sq ft; several planks feel soft when pressed, and the seams near the washer are open. The homeowner's insurer asks whether the floor can be dried and sanded. The inspector also places a 10 ft straightedge near the doorway and finds a 1/4 in. dip over a 4 ft span. The flooring runs under the washer and dryer and is trapped at a metal threshold. Indoor RH is 50%. A pin meter reads 12-14% on the wood subfloor near the washer and 9% in an unaffected area. The laminate has a 15-year residential warranty that excludes water damage.
1. Explain why laminate cannot be restored by drying and sanding after a water event. What happens to the core?
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Laminate is a composite product with a high-density fiberboard or similar core, a decorative print layer, and a wear layer. When water enters the joints, the core fibers absorb it and swell. The swelling is not fully reversible: as the material dries, the fibers do not return to their original dimensions, and the resin bonds within the core can be disrupted. The result is permanently raised edges, open seams, and softened planks. Sanding would remove the wear layer and the decorative print, exposing the core and destroying the floor's surface and warranty. Unlike solid or engineered wood, laminate has no meaningful sanding and refinishing allowance. The soft planks indicate that the core has lost integrity, not just surface swelling. Drying may reduce surface moisture, but it cannot restore the compressed and distorted core. The correct conclusion is that the affected planks must be replaced.
2. Evaluate the subfloor flatness reading against common laminate tolerances. Does it explain the swelling?
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The reading is 1/4 in. over a 4 ft span. Common laminate installation tolerances are on the order of 3/16 in. in 10 ft or 1/8 in. in 6 ft. Expressed per foot, 3/16 in. in 10 ft is about 0.019 in. per ft, while 1/4 in. in 4 ft is about 0.0625 in. per ft, more than three times steeper. The dip therefore exceeds typical flatness tolerance and would require patching or leveling before installation. However, the flatness defect does not explain the swollen edges and soft planks. Those symptoms are caused by the water leak and core saturation. The dip may have contributed to joint stress, flexing, or seam opening near the doorway, and it should be corrected before new flooring is installed, but it is a separate installation issue. The report should distinguish the water damage from the subfloor flatness deficiency and note that the subfloor moisture near the washer is elevated at 12-14%.
3. What should the inspection report recommend regarding replacement scope and subfloor repair?
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The report should recommend removal and replacement of all water-damaged laminate, which may extend beyond the 120 sq ft visibly affected because water travels under the floor and the floating system is continuous. Affected underlayment should also be removed. The wood subfloor should be dried and verified with a moisture meter before reinstallation; readings near the washer should be brought close to the unaffected baseline of about 9%. The subfloor should be checked for mold and delamination. The flatness dip near the doorway should be repaired by patching or leveling to meet the laminate manufacturer's tolerance before new flooring is installed. The report should state that sanding and drying cannot restore the laminate and that the water damage is excluded by the warranty. For insurance purposes, the cause is the supply-hose leak, not a product defect. Replacement should include new expansion gaps at the threshold and around the washer and dryer so the new floor is not trapped.