Leak Liability: Determining the Root Cause of Water Intrusion in a Food Processing Plant


The construction of a multi-million-dollar food processing plant is completed and operation in the plant begins. While the plant is operating, inspectors from the Food and Drug Administration (FDA) notice that water is traveling downward through the elevated floors and dripping on the process lines below, contaminating the product. Most of the issues occurred when the sanitation crew sanitized the plant each night.

The FDA inspectors offer the owners of the plant two solutions:

  • Prevent the water from traveling through the floors
  • Shut down the plant.

With door number two not being an attractive option, the engineering firm that designed the plant, the general contractor for the construction of the plant, and all subcontractors involved with the construction of the elevated floors were notified of the issues and asked to participate in an investigation of the facility.

At that point, EDT was contacted to determine the cause of the water problems.

Finding the Breach Source: Waterproofing Membrane Mystery

The elevated floors, from bottom to top, consisted of a precast concrete slab, a waterproofing membrane, three inches of cast in place concrete, and an epoxy surface. The epoxy surface was sloped to divert water falling on the surface to floor drains. Water that penetrated the epoxy and the cast in place concrete was intended to be collected on the water proofing membrane and removed by the floor drains. As a part of the investigation, sections of the epoxy and cast in place concrete were removed to expose the membrane.

Small, irregularly shaped holes in the membrane were observed in scattered locations, and gaps or separations were observed in the lap joint between adjacent sections of the membrane. The majority of the parties present for the investigation concluded that the membrane had been improperly installed, and that the sub-contractor who installed the membrane was therefore responsible for the water problems.

However, EDT’s investigation proved that this leaky liability issue wasn’t cut-and-dried.

Could Chemicals Be the Culprit?

As a part of the investigation, EDT collected a list of the cleaning products used by the sanitation crew, provided the list to the manufacturer of the waterproofing membrane, and asked the manufacturer about the effect of the cleaning products chemicals on the membrane.

The manufacturer revealed three key issues related to the waterproofing membrane:

  1. The membrane that had been installed was a roofing product and was not intended for use in a floor system that would be exposed to harsh chemicals.
  2. Multiple chemicals in the cleaning products would deteriorate the membrane if the membrane was exposed to the product for an extended period.
  3. One of the cleaning products used nightly at the plant would result in rapid deterioration of the adhesive used in the lap joints between adjacent sections of the membrane.

The chemicals in the cleaning products weren’t the only factors under review.

Was Welding During the Construction Process the Issue?

Daily logs from the construction of the facility showed that the general contractor allowed welding of the overhead structure to take place between the time when the waterproofing membrane was installed and when the cast-in-place concrete was poured.

Welding over the exposed membrane resulted in hot slag falling on the exposed membrane. The logs showed that three sections of the membrane were damaged by the slag to the extent that they were removed and replaced. The logs also showed that other sections of the membrane required spot repairs due to small holes having been burned in the membrane.

The holes burned in the membrane resulting from the overhead welding and the deterioration of the membrane resulting from the exposure to the chemicals in the cleaning products both allowed water to pass through the membrane and drip onto the process lines below.

Pinpointing the Problem: Construction Defect or Design Defect?

Allowing overhead welding while the membrane was exposed was a construction defect on the part of the general contractor. One of the responsibilities of a general contractor is scheduling the work of the sub-contractors so each step of the construction process can be completed at the proper time without damaging other work in process. The general contractor should have scheduled the welding for a different time or required that the membrane be protected while the welding was being done.

The specification of a waterproofing membrane for use in an environment where it was exposed to chemicals that resulted in the deterioration of the membrane was a design defect. Multiple improper steps were taken in the design process. A design that called for the use of what was intended by the manufacturer to be a roofing product in a floor system was a violation of the manufacturer’s recommendations.

The requirements and recommendations of the manufacturer of any product or material being used in a design should always be considered in the design process. In addition, the designer of any system or product has a responsibility to know the intended use of the item being designed.

In this case, the engineering firm that designed the facility should have been aware that multiple cleaning products would be used at the plant daily. While it is possible that the plant changed the cleaning products that were used in the sanitation process after the plant began production, a change in the products was foreseeable and should have been considered.

In addition, with the water problems in the plant starting shortly after production began, it was unlikely that any changes to the products had been made.  The use of what was intended to be a roofing product in a floor system, and the failure to consider the environment that the membrane would be exposed to are both construction defects.

So, who's ultimately responsible for the water intrusion?

The Verdict: A Shared Responsibility

Initially, most parties involved in the investigation determined that the water problems were the result of defective work by the sub-contractor who installed the membrane. However, a deeper dive into the design and construction process showed that the sub-contractor had conducted his work in accordance with the project documents. The sub-contractor used the products that were specified and installed them according to the requirements of the design drawings. No defect in the work done by the sub-contractor was found.

A thorough investigation of the design, construction, and maintenance of the facility, including removing a portion of the cast concrete to reveal the waterproofing membrane, allowed EDT to determine the leaky floors to be a result of design defects by the engineering firm that designed the plant and construction defects by the general contractor.

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