Air Leakage in Commercial Buildings: What is It and Why Should You be Concerned?

Insulation and controlled ventilation are essential for commercial structures and residential buildings alike. This is not a novel concept of course and most business owners are well aware of why those are so important. Companies do take the mandatory, standard precautions for improving insulation and keeping unwanted heat exchange from becoming an issue. Unfortunately, that may not always be enough to prevent air leakage.

Air Leakage: What If Air is Leaking Through the Walls themselves?

We consider walls as solid barriers between the indoor and the outdoor environment, but unless sufficient measures have been taken, walls may not be as solid as we believe them to be. If the walls of a building are more porous than they should be, or in case their structural air barrier thickness has decreased over time, air can pass directly through them. This is the definition of air leakage and if left unchecked, it can lead to a series of financial, structural, and health problems.

This could be a result of improper air barrier thickness calculation, or perhaps the initial choice of air barrier material itself was poor in respect to the structure, its needs, and the applicable environmental conditions. It is possible to both prevent and stop air leakage via the application of fluid-applied/sheet-applied air barriers, vapor permeable air barriers, or flashing membranes. To learn more about preventing air leakage, calculating air barrier thickness, and the right choice of materials, visit W.R. Meadows. As to why you may want to do so, let’s focus on the compounding problems that arise from uncontrolled air leakage.

Damp and Mold

Although air leakage is not the only factor responsible for facilitating mold growth in any building, moisture-laden air that can permeate and pass-through walls presents a deeper concern. The problem with mold that grows from air leakage is that it will almost always grow between two walls and sometimes, even inside the walls. Given that these are generally sealed areas, the fungus can stay inside and spread without being checked for years.

In most cases, mold and moisture damage from air leakage is only discovered after it becomes bad enough to be visible from inside and/or outside the building. By that time, the construction materials will have already been severely degraded. It’s also likely that the growing damp and mold will start to degrade the surrounding indoor air conditions significantly, long before the damage becomes visible.

Growing Concerns Related to Health & Hygiene

Mold and damp together are responsible for causing multiple health problems in commercial and residential buildings. Common examples include but are not limited to:

  • Permeating and lingering stench
  • Prevalence of common cold symptoms, frequent sneezing fits, aggravated asthma, allergic reactions, etc.
  • Insufficient heating/cooling during the winter/summer months
  • Uneven indoor temperature control, leading to hot/cold spots


Efflorescence is a complex chemical reaction and phenomenon where unsightly white/brown/green/yellow powdery salt deposits are found on a building’s walls, roof, and/or any other constructed surface. In case the building in question is susceptible to efflorescence, it will become visible at any time between 1 – 12 months from the surface’s initial construction.

Air leakage occurs when the walls are too porous and, incidentally, that is also a requirement for efflorescence. If there are water-soluble salts within the walls’ construction and humid air is passing through them, then efflorescence is inevitable without air barriers. The same permeable nature of these walls will also allow water-soluble salts to seep out of the walls, along with the moisture itself. Once the moisture dissipates, the salt will be left behind in clusters.

It is recommended that the problems be taken as symptoms of high permeability and attended to at the earliest. Delays will only make your building’s surfaces even more porous with time, which will naturally raise future expenses.

Published by Kidal Delonix (1197 Posts)

Kidal Delonix is a contributor to Mr. Hoffman's blog. The views and opinions are entirely his/her own and may not reflect Mr Hoffman's views.

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