Avoid Catastrophic Mold and Moisture Problems in Hot, Humid Climates Due to Air Barrier Standard Confusion

 

By George DuBose, CGC; Richard Scott, AIA, NCARB, LEED AP; and Donald B. Snell, PC CIEC

 

Imagine the following scenario: you just designed your newest project to meet the most current whole building air leakage standards, and your mechanical engineer subconsultant has designed an HVAC system that includes one of the latest energy recovery strategies. Both factors are intended to meet high energy efficiency goals, making you proud that your firm is doing its part (amongst other things) to minimize your impact on the climate change problem.

Continue Reading Till Death Do Us Part: Preventing a Facade and HVAC Divorce When It Comes to Air Barrier Performance

 

Just months after completing refurbishment on a 300+ room resort, the owner of a luxury coastal vacation resort began to wonder if he had entered into the Twilight Zone when mold and moisture problems suddenly emerged in numerous guestrooms. He was perplexed that this problem was cropping up now despite the fact that he had owned and operated similar properties for many years. Never in all that time had he ever experienced moisture-related issues.

 

Why was the problem occurring at this point? What was different?

Continue Reading Has Coastal Zone Hotel Construction Become the Twilight Zone for Mold & Moisture Control?

 

After over 25 years of figuring out why buildings end up as catastrophic mold and moisture building failures – there are some apparent truths that have remained seemingly unchanged.

 

 

Buildings should not be designed in silos (but they still are). Despite advances in technical understanding and higher standards for building performance, like building envelope airtightness, the design task for the building envelope is still being completed in a vacuum of other critical disciplines. On a recent project, the facade consultant was asked how their design interfaced with the overall building pressurization requirements established by the HVAC design. The answer: “We don’t consider that in our design. They do their thing and we do ours.”

 

Continue Reading You Can’t Fake the Funk: After 25 Years of Consulting, Here are Three Forgotten Truths about Mold and Moisture Building Failures

 

Here is an all-too-common scenario: A design and construction team is awarded a new hotel project. The design and construction standards are passed on to the team. The team adheres exactly to the requirements of exterior wall design and HVAC system design only to discover during final stages of construction that the actual performance of the design is vastly different than expected.  Unsuspecting hotel design and construction teams need to heed the warning: “Rigid adherence to hotel design and construction standards without factoring in specific regional and climatic conditions can result in significant mold and moisture issues in new hotel construction.”

 

Continue Reading Clash of the Titans: When Hotel Design and Construction Standards Cause Catastrophic Mold Problems

The theory behind design and construction (D&C) standards is to provide assurances that the hotel is built to requirements that meet the brand’s expectation for aesthetic, operational, and building performance. D&C standards portray themselves as a repository of lessons learned and of what should be done (and, by implication, what should not be done) to make the hotel work. However, theory proves contrary to actual practice in this case because D&C standards are developed on a global basis. They typically do not take into consideration specific needs and limitations of regional climates. In fact, it has been found that these  D&C standards often don’t comply with recommended building practices for certain climates at all. These violations in the D&C standards have been shown repeatedly to result in extensive and costly mold and moisture problems in hotels.

 

In the case of a 140-room hotel in a warm and humid climate in Texas, the hotel began to experience significant mold and moisture problems that resulted in more than $5 million of damage claim against the general contractor. D&C standards for the hotel required that the mechanical system provide roof top units (RTUs) for conditioning of the corridors with 10% additional outdoor air for building pressurization. Liberty’s measurements of relative pressurization confirmed the cause of visual evidence of mold growth behind the VWC. With all HVAC systems operating (RTUs, PTACs, and toilet exhausts), the guestrooms were and wall cavities were under high negative pressure relative to outdoor air. Even with the toilet exhaust fans turned off, guestrooms were barely under positive pressure, and some were still under negative pressure (see Figure 1). Negative pressurization, as a result of misapplication of brand standards, results in drawing in of warm, humid air which leads to mold growth.

 

Continue Reading Brand Demands: Can These Be The Cause of Catastrophic Mold Problems?