First, confirm the problem
- Check that the method used is the one the product instructions name, and that the building was at service conditions.
- Look at every location, not the average. One wet area may need a different plan from the rest.
- Rule out active sources: leaks, irrigation, drainage. No coating fixes water that keeps arriving.
The usual paths
More time, better conditions
On new slabs with schedule room, running the building at service conditions longer and retesting may be enough. It costs time rather than materials.
Different products
Some adhesives and flooring systems are written for higher moisture limits than others. Changing the selection can change the outcome without adding a layer.
A mitigation system
Moisture-mitigation coatings and membranes are applied over the prepared slab to limit the moisture reaching the floor covering. ASTM F3010 covers two-component, resin-based, membrane-forming systems used under resilient floor coverings, and defers to the manufacturers’ written instructions.[5]
What a mitigation decision depends on
- The written limit of the system. Mitigation products publish their own maximum moisture conditions, test method and preparation requirements.
- Compatibility. Primers, patches, self-leveling underlayments and adhesives above the membrane all have to be approved to work together.
- Surface preparation. Many systems need a mechanically prepared surface, which affects schedule, dust control and any old residue on the slab.
- Warranties. Find out which manufacturer warrants what. Some offer an assembly warranty when their products are used together.
- Cost and schedule. Time, materials and cure periods all compete with the move-in or opening date.
For new construction: prevention is cheaper
Below-slab vapor retarders are specified to limit moisture moving up from the ground. ASTM E1745 covers the plastic sheet materials used for this purpose,[6] and ACI publishes design guidance for slabs that will receive moisture-sensitive flooring.[7] Decisions made before the pour, and building conditions after it, have a large effect on how long the slab takes to be ready.
What this page does not cover
Step-by-step application, product recommendations, or a diagnosis of a failed floor. Those belong with the product manufacturers and the professionals responsible for the project.
Start with the facts: understand your result and check the report.