Rapid RH and Carbide Bomb: The Pros & Cons of Each

Moisture testing determines whether a flooring installation lasts. Two common methods are the Rapid RH® test and the calcium carbide test, often called the carbide bomb test. Here’s how they compare.

Pros and Cons of the Carbide Bomb Test

Pros Cons
Gives a number: total moisture content as a percentage by wet weight The scale and pressure gauge need regular calibration
Fast for one-off readings Very slow for profiling, since tests have to be run one after the other
Has good credibility on job sites The reaction gives off acetylene, a flammable, explosive gas
Results depend heavily on correct sampling and technique
Destructive: each sample is drilled or chipped out and used up in the test
Interpreting results takes training and experience
Each test uses calcium carbide reagent, so taking many readings adds cost and waste

Pros and Cons of the Rapid RH

Pros Cons
Low initial investment Requires drilling small holes in the slab
Low cost per test You need to know the slab thickness to set the hole depth (40% of the thickness for a slab drying from the top only)
Easy to use
Sensors stay in the slab, so you can take repeat readings as it dries
Profiling a floor slab is possible and easy
Widely accepted in the flooring industry (ASTM F2170)
Official ASTM F2170 readings after just 24 hours, with each reading taking seconds

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Last updated on October 22nd, 2026