Meter Says Dry, Floor Says Otherwise
A 1,200 sq ft retail boutique has a 4-in concrete slab with glued-down luxury vinyl plank (LVP). A roof drain overflow sent category 1 water across the sales floor for about 40 minutes; water was extracted within an hour. Baseboards are MDF, drywall is 5/8 in, and the bottom 12 in of drywall in two exterior walls got wet. Three days later, a pin-type meter reads 0.3% on the LVP surface and 11–14% on the MDF baseboards. A pinless meter reads high near two LVP seams and low in the field. A thermal camera shows a cool band along the exterior wall and near the front entry. The LVP looks flat, with no visible cupping. The owner wants to keep the floor and reopen in 48 hours. The adjuster asks whether the floor can be dried in place with air movers and a dehumidifier.
1. Interpret the meter and thermal findings. What inspection steps would you take before deciding whether the LVP can stay?
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The pin meter reading on LVP is not a moisture-content reading of the slab or adhesive; it is strongly influenced by surface contact and the flooring's low conductivity. The pinless meter's high readings at seams may indicate moisture trapped below or at the adhesive line, or simply a density/contact artifact; it is not conclusive. The thermal cool band is likewise a clue, not proof. Before deciding, I would lift a transition strip or cut a small inspection opening at a seam, use a pin meter on the exposed slab and on the subfloor/adhesive, and place an in-situ relative-humidity probe in the slab if the slab is the assembly. I would also check the baseboard cavity and drywall with a penetrating meter and compare to unaffected areas. If moisture is trapped under a non-breathing floor, air movers above the LVP will not dry it.
2. The owner refuses removal. What drying approach, if any, would you propose, and what would you tell the adjuster about risk?
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If the LVP is glued down and the slab is wet, drying in place is generally not defensible because the floor is a vapor retarder and air movers cannot reach the adhesive or slab surface. I could propose a limited test: contain the area, maintain 45% RH or lower, direct airflow across seams and at removed baseboards, and monitor with in-situ probes at multiple depths for 24–48 hours. If readings do not fall toward the dry standard, removal is required. I would tell the adjuster that a dry surface reading is not evidence of a dry assembly, that the floor may delaminate or support mold, and that documentation should include the failed test and the removal recommendation. Reopening in 48 hours without verification would be a risk the contractor should not accept in writing.