Understanding Hydrostatic Pressure in a Concrete Slab

In this video, Rapid RH® product specialist Jason Spangler explains what hydrostatic pressure in a concrete slab really is.

Concrete can be a problem when we do not comprehend the fundamental construction terms related to its installation. The term, hydrostatic pressure, is often misused to describe the dangers of moisture. High relative humidity (RH) levels and hydrostatic pressure can both ruin floors. However, contractors overestimate and overuse the words hydrostatic pressure when discussing flooring failures.

To learn more about hydrostatic pressure, click here.

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Last updated on August 31st, 2021


  1. Richland Concrete says:

    Good explanation and good visual. I just did this with my kids to help them understand. Thanks, I appreciate the help

  2. Michael Trama says:

    I live in a first of a 2 floor Condo in Greenacres, FL. Sub structure is a concrete slab Had laminate flooring installed through out the condo in September 2017. Specs: vapor barrier, foam underlay, boards are 12 mm thick x 8 in.x 48″. Total job: 900 sq ft (2 BR, L. room, D. room, hallway). Within weeks I started seeing end to end and buckling in certain areas. Had the installer inspect my flooring issues. Moisture meter ~9%. No water/wet spots or cracks observed. He says there is a high point running diagonally across my living room (15’). An 8 ft level placed in the middle at what he refers to as the “high point” shows ~1/2” gap at both ends. His conclusion: during the past 3 years hydrostatic water pressure has pushed up areas of the slab concrete foundation resulting in end to end board lifting.
    I believe at the initial inspection to take measurements and check for levelness, the inspector missed checking the floor diagonally, only front to back, left to right. Can hydrostatic water pressure selectively push up some areas of the slab, but not the entire slab? Does this sound plausible?

    • Jason Spangler says:

      Thanks for the question. Anything is possible, but this doesn’t seem very probable. I would contact an organization like this https://www.nicfi.org/ and find an independent inspector in your area to evaluate the situation. Good luck.

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