A premium hardwood floor is one of the worst places to discover that “the slab felt dry” was the entire moisture test. Concrete contains water when it is placed, interacts with ground moisture, and dries according to conditions—not the construction schedule.
The nightmare
Wide-plank hardwood is installed throughout an open plan. Then edges cup, boards crown, adhesive softens, dark staining appears, or the floor releases in sections. The installer blames the HVAC. The builder blames the flooring. The flooring representative asks for moisture records that do not exist. Meanwhile, the homeowner is moving furniture out of half the house.
What should have happened below the slab
The assembly needs properly prepared subgrade, a capillary break, and an appropriate below-slab vapor retarder detailed around penetrations and edges. Those layers are easiest to do correctly before concrete and difficult to reconstruct after a failure.
What should happen before flooring
The flooring product, adhesive or underlayment, slab, and site conditions must be treated as one installation system. Use the moisture tests and limits required by the flooring and adhesive manufacturers and applicable industry guidance. Document results. Confirm the building is at appropriate service conditions. If mitigation is required, specify a compatible system rather than buying a mystery coating after the truck arrives.
Wood also needs preparation
Hardwood needs the manufacturer’s required acclimation and storage conditions. Subfloor flatness, species, board width, installation method, indoor humidity range, and seasonal movement all matter. Real wood moves; the goal is to keep that movement within the system’s ability to tolerate it.
This article is general educational guidance, not a project specification. Site conditions, plans, manufacturer instructions, engineering, adopted codes, and local requirements determine the right details for an individual home.