The Wait for Concrete to Dry

A building project is typically handled in a series of stages, each with its own manager. The goal is always to hand off each stage from one manager to the next without delays. But when moisture-sensitive flooring is involved, one part of the job can throw a wrench in the process: the concrete slab.

What’s Required for a Successful Flooring Installation?

For a flooring installation to be successful:

• The slab’s moisture and pH levels need to be within the acceptable range.
• The slab must be protected from outside moisture.
• The slab’s moisture level must be compatible with both the specified floor covering and the flooring adhesive.
• The potential for moisture emission from the slab must be addressed.

What Factors Delay a Slab’s Drying Time?

Many industry standards guide how a concrete slab is placed and dried, but the drying time for any slab is almost impossible to predict. The factors that affect drying time are unique to each installation. They include:

• The components of the original concrete mix
• Ambient air humidity
• Final service conditions
• Surface finishes
• How well the HVAC system is working
• Floating practices or rewetting

When any of these factors change during the project, the concrete may need more time to dry. Delays in getting a properly dried slab can throw off the entire construction schedule.

Is It Better to Wait for the Slab to Dry or Forge Ahead?

Lost labor hours and added costs are two results of schedule interruptions on a construction project. But the alternative, pushing ahead despite the slab’s condition, risks flooring failure. A moisture-related flooring problem is a no-win situation for everyone involved, from contractors and construction managers to flooring installers, adhesive manufacturers, and facility owners. Experience shows that installing flooring before the slab’s moisture issues are resolved costs far more than waiting and getting it right the first time.

All Eyes on the Goal, Not the Clock

The ultimate goal of a construction project is an installed flooring system that stays problem-free for the long term.

When the construction schedule leaves no room to deal properly with moisture in the concrete, there’s a temptation to rush the project, and that invites flooring failure.

Free Download – 4 Reasons Why Your Concrete Is Taking Forever to Dry

How to Know When the Slab Is Ready

Some methods, such as desiccant drying and surface treatments, can help speed up drying. But how can the flooring contractor be sure the slab’s moisture level is compatible with the moisture-sensitive adhesive and flooring on the project?

Accurately measuring the relative humidity (RH) within the slab is the best way to know when the slab has dried enough.

Surface-only indicators of a slab’s moisture condition, such as calcium chloride testing, aren’t reliable, even though they have been widely used in the industry.

In-situ RH testing is better than surface-only testing because it reflects the RH conditions the slab will reach under an installed floor. With accurate knowledge of the slab’s RH, the general contractor and flooring installer will know whether to allow more drying time to meet the adhesive and flooring specifications, or to choose a different adhesive or flooring product that’s compatible with the slab’s current condition. RH testing gives everyone on the project the information they need to decide whether to wait or move on to the flooring installation.

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Jason Spangler

Jason has 20+ years’ experience in sales and sales management in a spectrum of industries and has successfully launched a variety of products to the market, including the original Rapid RH® concrete moisture tests. He currently works with Wagner Meters as our Rapid RH® product sales manager.

Last updated on October 9th, 2026