It's also important to understand how air barrier goals are difficult for architects and contractors to achieve, and how building air barrier performance is as much about the HVAC system as it is the air barrier itself.

We are now offering new short courses to individuals and organizations who wish to become more prepared and educated about damage claims. Our first two, featuring building envelope and water damage, target attorneys and contractors.

Once again, we're offering a free download of our mold and moisture manual that provides the latest information to designers, contractors, and building owners on today's key issues.

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There's a new edge in risk management concerns for the building industry, says Florida-based Liberty Building Forensics Group® (LBFG), a leading building forensics firm that has solved some of the world's largest and most complex building moisture and mold problems.

Buildings with hidden flaws are experiencing acute massive failure that results in extensive moisture and mold damage. These failures, termed "zombie defect failures", are often discovered only after several years and a major event like a renovation or sale occurs. Examples include incompatible products and HVAC piping failures. 

"We're not talking about chronic problems here," said LBFG's Donald B. Snell, P.E. "These are acute building failures requiring unique skill and vast experience in how building systems interact. Complex mechanical building systems may take years to build but only seconds to fail."

The building owners may get paid easily from their insurance companies after a failure occurs, but subrogation of the case by the insurance company often becomes a complicated, prolonged mess. This means the insurance company takes on the owners' rights, assuming the difficult role of tracking down all players involved leading up to the building failure and proportioning costs to the various (often elusive) responsible parties. 

Failures usually happen at the intersection of scopes of work, meaning more than one party is to blame, and that is when having the necessary skill and expertise comes into play.

Responsible parties make many excuses as to why they should not be responsible. These range from "you bought the building as is, so it's not my problem", to "their product was not compatible with ours", "the other guy's work failed, not mine", "we met code so don't blame us", and "my work was first, not my issue". 

LBFG brings expertise in deconstructing complex, moisture-related subrogation claims (especially those related to massive moisture damage) and apportioning consequential damages to the appropriate parties. Our experts look into the nuances of what causes such failures to gain a heightened awareness of how to prevent them in the future.

Additionally, architects often find it difficult to translate air barrier performance criteria into specific design details, while contractors find it even more challenging to translate them into the construction itself.

Contractors don't know if they've met the design leakage criteria until the end of a project, since whole building air barrier testing can only be performed after a building is completed. By then, it is difficult to locate leak sites, and removal of completed construction is required to fix the problem.

"Building tightness is extremely important in increasing the drying potential of a wall," said LBFG Vice-President Richard Scott, AIA. 

"A well-constructed building with a good air barrier helps the HVAC system pressurize the building with conditioned air, which increases its drying effectiveness. HVAC systems in warm, humid climates need to pressurize properly, and a proper, continuous air barrier is necessary to accomplish this. After all, you can't pressurize a box with one side open."

This factor is especially important in buildings where a great deal of air movement occurs across areas of small square footage, such as hotel guest rooms, patient rooms in hospitals, high-rise and multi-family condos and apartments, assisted living, and nursing home units.