The Reason Why Mold and Moisture Issues are Commonly Misdiagnosed in Buildings

The human body requires harmony between its various bodily systems. When diagnosing a problem, the best doctor understands that while a specific symptom in the body may seem to be isolated, it typically points to a deeper issue. Similarly, the best design, construction, and forensic experts understand that they do not work in a vacuum or develop their component in a silo, independent of other building counterparts. Due to the complexity of buildings, for every one issue that is being addressed, a number of other factors must also be considered in order for the building systems to be able to perform in an integrated manner.

Acknowledging All Aspects of a Building

The presence of what may appear to be independent HVAC and building envelope (BE) defects commonly leads to a misdiagnosis of building dampness problems. This is often due to a misunderstanding of the interactions between the HVAC and BE systems. This lack of emphasis can have a cascade effect that starts in design, follows through construction, may be exacerbated by operation and improper maintenance, and is forensically misidentified in expert witness testimony after a building dampness failure occurs.

mold damage to exterior window wall and interior drywall in humid climate
Damage to an exterior window wall and on the interior drywall in a Florida hotel.

For example, when damage occurs on the exterior window wall of a hotel it is often attributed to rain water damage without consideration to an air infiltration problem. These photographs from a hotel in Florida show damage to a painted exterior window wall with visible damage on the interior drywall. The visible damage patterns at the electrical outlet point towards an air infiltration problem. Many times the damage is believed to be limited to just one source because as consultants we can show biases to one mechanism over the other. Those with an extensive BE focused background will tend towards mechanisms like rainwater intrusion or vapor diffusion. Those with a heavy HVAC background may tend to see the problem as a pressurization driven issue, when it actually can be a combination of all of these mechanisms. When developing a causation opinion it is important to be able to differentiate between these mechanisms and to be able to divide the physical damage between each mechanism even when they seem to overlap. Then, based on an analysis of the deficiencies and what scopes of work caused the deficiencies, one can better assess the cause of the damage amongst participants and one can better understand what will be required to correct the problem.

What an Integrative Approach can Accomplish

An oversight of HVAC and BE interactions occurs because multi-disciplinary approaches are not taken and intersections of scopes of work are overlooked. Properly focusing on these intersections allows for:

  • Multi-disciplinary approaches to complicated moisture problems that include both architectural and mechanical expertise.
  • Continuity of BE control layers that are designed to meet best practices, detailed to illustrate each intersection of work and designed for practical and effective installation.
  • Recognition that the biggest scope of work, the HVAC system, is often overlooked.
  • Identification of the most influential driving mechanisms for building air infiltration.
  • Understanding of the influence of planned and unplanned openings in air infiltration.
  • Awareness that the building HVAC system must continuously maintain a dew point temperature of 60℉ to minimize the risk of building moisture problems.
  • Self-assessment on the standard of care for each phase of the work.

Minimizing the potential for HVAC and BE defects warrants careful review and appropriate modifications to standard practice by designers, contractors, and forensic experts. Continued lack of emphasis on the interaction of the HVAC and BE system reflects an industry failure to recognize the risk and consequences for building dampness and mold. These interactions of a building’s systems should not be overlooked and can be the key factor when diagnosing mold and moisture problems.