The Real Costs: Calcium Chloride (CaCl) vs. RH Testing

For years, the debate between anhydrous calcium chloride (CaCl) and relative humidity (RH) testing has been ongoing in the realm of concrete moisture testing.

Flooring contractors have long relied on these methods to assess the moisture levels of concrete slabs before installing finished floor products. While CaCl has been a traditional go-to for its cost-effectiveness, RH testing has emerged as a more comprehensive alternative in recent years.

Let’s delve into the comparison between these two testing methods to determine which one truly reigns supreme in the world of concrete moisture testing.

For decades, flooring contractors have conducted moisture tests to verify the appropriate “dryness” of a concrete slab, prior to installing finished floor products. The anhydrous calcium chloride (CaCl) provided a moisture vapor emissions rate (MVER) which was the industry benchmark since the 1950s.

In the 1990s, experts raised methodology concerns and suggested that the CaCl test did not indicate a thorough enough measure of concrete moisture condition. Since then, relative humidity (RH) testing has emerged as an alternative. Both tests may still be used, but many may ask: which one is best?

CaCl Test vs. RH: Materials

The first place most businesses would look to answer that question is cost. And cost alone would make it seem that CaCl comes out ahead. If contractors apply the CaCl test in 13 locations of a 10,000 square foot slab, they pay a materials cost of $147.95, or $11.38 per test.

In the building business, the CaCl test may appear to be cost-effective.

Bottom LineCalcium Chloride (CaCl)Relative Humidity (RH)
Material Costs (13 tests)$147.95$600.00

CaCl Test vs. RH: Time

But time equals money, too, and it is there that the anhydrous CaCl test becomes a heavyweight. If contractors place in-situ RH probes at 40% depth in 13 locations of a 10,000 square foot slab, they can obtain overall RH assessment in 94% less time than the anhydrous CaCl test.

By deploying RH testing, contractors save 54.82 man hours of cost.

Test TaskCalcium Chloride (CaCl)Relative Humidity (RH)
Prepare test locations65 minutes0 min.
Prepare the test65 minutes0 min.
Place the test65 minutes65 minutes
Protect the test120 minutes0 min.
Obtain results130 minutes3.5 minutes
Cleanup20 minutes7 minutes
Time Required (13 tests)4,320 minutes (72 hrs.)120 minutes (2 hrs.)
Total Test Time3,495 minutes (158 hrs. 15 min.)205.5 minutes (3 hrs. 25.5 min.)

Multiply the Savings

Contractors pay an extra $452.02 for a moisture test based on RH, and they save 54.82 man hours for it. Further, the CaCl test measures moisture vapor emissions at the slab surface. It does not indicate moisture levels or moisture migration through the concrete slab.

Measured by both time and test integrity, RH concrete moisture testing appears to hold a long-term edge despite higher up-front costs.

What to do with 54.82 hours of your budget? Hire contractors! Here’s how long you could employ the following trades people based on the amount saved on moisture testing ($452.02) multiplied by their average national wage in 2022:

Job/TradeTime (Hrs.)
Civil Engineer12.29
Construction Laborers31.56
Environmental Engineer12.92
Floor Layers24.67
Concrete Finishers26.2
Drywall/Tile Installers24.29

Source: US Bureau of Labor Statistics (Web).

In a constrained budgetary world, the RH test trumps the anhydrous CaCl test on both methodological and economic grounds. Concrete slabs and construction projects gain.

Free Download – Which Rapid RH Sensor is Right For You?

Last updated on March 25th, 2024

Leave a Reply

Your email address will not be published. Required fields are marked *