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Concrete Moisture Conditions For The Application Of Moisture-Sensitive Flooring

You invest heavily in making your flooring attractive, durable, and long lasting. They indeed reflect a soothing ambiance and almost redefine your space. However, if you are about to apply moisture-sensitive flooring, you should make sure to take due care of all the associated threats. Otherwise, concrete moisture conditions can affect it adversely, leading to the flooring’s gradual destruction.

Consequently, this influences all the involved stakeholders whether space owners, users, construction managers, contractors, or floor installers. The speed of the project suddenly suffers a break down, budget goes out of control, and disturbance in everyone’s schedules becomes a commonality. Here are few considerations to help you reduce the risk of concrete moisture conditions affecting your moisture-sensitive flooring.

Applying the moisture-sensitive finishes successfully

Various factors contribute to the successful application of moisture-sensitive coatings and finishes. Prominent of these include:

    • Deep knowledge of the sources of moisture in concrete
    • The way the concrete’s moisture content dries with time
    • Factors that impact the drying rate
    • The drying percentage of the concrete before the finish installation
  • Allowing adequate drying time for the floor

Apropos to the last point, in the absence of sufficient drying time, various moisture sensitive finishes like timber, epoxy based terrazzo, surface coatings, vinyl, and carpet, among others, could lead to severe moisture related problems.

Estimating the drying time

Try to determine whether the concrete is dry enough before applying the moisture-sensitive flooring. This gives a settle idea whether the moisture is drifting away from the surface or moving toward it. Several methods help you significantly in this regard, such as:

    • Rule-of-thumb: This method allows drying time of 30 days for every 25-mm thick concrete slab since the last re-wetting or curing completion.
    • Water-cement ratio: As per research, for 0.5 value of water-cement ratio, the sufficient drying time for a 100-mm-thick concrete slab is three months, 150-mm thick slab is 12 months, and for a 200-mm thick slab is 12 months. These durations reduce to half if the slab can dry from both the sides.
    • Swedish Concrete Association method: This method modifies the standard drying time for ambient temperature, humidity, slab thickness, and curing and drying conditions.
    • Vapor emission rate approach: It indicates the moisture content remaining in the concrete. Depending on the flooring material, this approach recommends the ideal vapor emission rate to lie between 15 to 25 g/m2/24 h (3 to 5 lbs/1000 ft2/24 h).
  • Moisture content/Relative humidity approach: It states that the value of moisture should exceed 5.5% and humidity level should exceed 70% to lay down the textile flooring.

Measuring the acceptable level of moisture

Various methods exist to determine the moisture acceptance criterion in the concrete, which is fare enough for the application of moisture-sensitive finishes. These include:

  • Hygrometer test
  • Electrical resistance test
  • Calcium chloride test
  • Gravimetric moisture content test
  • Rubber mat test
  • Glass sheet test
  • Plastic sheet test
  • Test panel

Besides these, contour mapping also gives a settle indication of the high and low moisture areas in the concrete slab, which helps you effectively in the application of moisture sensitive flooring.

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