Finding a Cure for Sweating Slab Syndrome

Despite the significant strides in medical technology in the 21st century, identifying a cure for the common cold is still one of medicine’s most elusive pursuits. Similarly, the phenomenon in warehouse operations known as sweating slab syndrome (SSS) has perplexed even the most experienced industry experts when it comes to the causes and potential cures.

The concept of unwanted moisture on floor slabs in distribution and manufacturing buildings has been a challenging factor since the dawn of concrete floor systems. Yet, with modern distribution center (DC) advancements in materials handling equipment, safety features, and information technology, the often unexplained mystery and cure for the sweaty slab still remain relatively unsolved today.


First, an examination of what causes moisture issues on a warehouse floor slab is worthy of consideration. In most cases, slab sweat develops as warmer air interfaces with a cold slab surface. In scientific terms, the sweat or moisture manifests as warm, moist air enters the warehouse—through an open dock door, for example—and condenses on the colder slab surface at or below the dew point temperature.

The phenomenon is more common in warmer regions of the country where high humidity conditions exist, and like the common cold, slab sweat can be seasonal. Moisture build-up on concrete occurs more frequently during the spring and fall seasons as temperatures fluctuate, particularly as cooler nights yield to warmer daytime temperatures.

Temperature fluctuations aren’t the only culprit in the emergence of slab sweat. An untidy warehouse floor can create or exacerbate the issue. For example, boxes or stacks of corrugated left on the floor slab for an extended period of time can limit the slab’s ability to “breathe,” causing moisture build-up. Oil from forklift traffic and grit from standard warehouse operations can add to the floor slab’s moisture build-up.

Safety is the major concern when moisture pools on a warehouse floor surface. According to the National Floor Safety Institute, the majority of workers’ compensation claims are linked to employees falling and injuring themselves on a slick floor surface. Not all these claims are tied to SSS, but sweaty warehouse floors are a major factor in causing warehouse injuries.

Who’s to Blame?

While most experts consider the phenomenon to be caused by weather-related conditions, the question remains, “Who is responsible for addressing the sweating slab issue?” Typically, tenants will push landlords to mitigate the problem, but landlords don’t have all the answers and justifiably don’t want to assume full liability for the potentially litigious issue. In some scenarios, landlords will deem the contractors who constructed the building liable, challenging the contractor to verify that a moisture or vapor barrier was installed between the dirt floor elevation and the concrete pour. A typical moisture barrier is simply a plastic sheet placed on the compacted dirt prior to the concrete pour.

In an extreme case several years ago, a landlord chose to completely remove a perineal sweaty floor and re-pour a new 4-inch slab. After exploring all options to remediate the building’s sweating slab, the property owner concluded that the best solution was to terminate all three leases in the distribution building and extract the existing slab. A basic vapor barrier was installed and a new concrete slab was formed, terminating the moisture issues.

Cures for the Common Cold Slab Syndrome

Proposed cures for SSS are not “one size fits all.” However, experts agree that constant air flow is the first line of defense to mitigate floor sweat. With recent advancements in warehouse air circulation, installation of slow-moving, super-sized roof-mounted fans have proven to be the most effective, and inexpensive, solution to minimize slab moisture.

Other practical solutions—other than installing warehouse air conditioning—include stacking floor-loaded inventory into warehouse racks or on pallets. Additionally, when applying a warehouse floor seal, consult an industry expert and inquire before application to ensure the seal will not increase the likelihood of SSS.

Like the common cold, the phenomenon of a sweating warehouse floor slab is not easily eliminated, so DC occupants and building owners should consider practical remedies before a major insurance claim saddles all parties.

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