In the flooring industry, surface moisture content (also known as moisture vapor emission rate or MVER) refers to the amount of moisture present within a concrete slab or other subfloor material. Understanding and controlling surface moisture content is crucial to ensure successful flooring installation and prevent potential problems.
What is an Acceptable Damp Reading?
Acceptable damp readings vary depending on the flooring type, adhesive or underlayment used, and environmental conditions. Generally, the following surface moisture content readings are considered acceptable:
- Concrete subfloors: 5% or less using a calcium chloride test, or 75% relative humidity (RH) or less using a probe meter
- Wood subfloors: 12% or less MC using a moisture meter in the pin or probe mode
- Anhydrite screeds: 0.5% or less MC using a calcium chloride test, or 65% RH or less using a probe meter
Importance of Controlling Surface Moisture Content
Excessive moisture content in the subfloor can lead to a range of problems, including:
- Buckling and warping of flooring materials
- Adhesive failure, leading to delamination
- Mold and mildew growth
- Corrosion of metal components
Measuring Surface Moisture Content
Properly measuring surface moisture content is essential to determine if the subfloor is suitable for flooring installation. Several methods can be used, including:
- Calcium chloride test: Measures the amount of moisture absorbed from the subfloor by a calcium chloride solution
- Probe meter: Measures the relative humidity or moisture content of the subfloor
- Vapor pressure meter: Measures the vapor pressure emanating from the subfloor
Controlling Surface Moisture Content
If surface moisture content exceeds acceptable levels, steps must be taken to control it. This may involve:
- Allowing the subfloor to dry naturally
- Installing a vapor barrier to prevent moisture from rising from below
- Using a dehumidifier to remove excess moisture from the air
By understanding surface moisture content and taking appropriate measures to control it, you can ensure the successful installation of your flooring and prevent future problems.