Building Envelope Failures

Building Envelope & HVAC Interaction
in Warm, Humid Zones

By George H. DuBose, CGC; Richard Scott, AIA, NCARB, LEED AP; and Donald B. Snell, P.E., Cert. Mech. Contractor, CIEC

building failures
This high-rise resort in Central Florida underwent a $9.5M remediation only to have the problem come back the first summer after it was complete.

Certain faulty beliefs surrounding building performance in warm, humid zones continue to persist in the design and construction industry – and the interaction between building envelopes and HVAC systems is no exception.

Unfortunately, the fact that many architects and engineers rely on such myths as gospel truth during building design has inevitably led to building failures that are often catastrophic in scope.

Below is one prevalent myth our experts at Liberty Building Forensics Group (LBFG) have encountered through their extensive work resolving mold and moisture problems in hotels and resorts. The myth is followed by an explanation of why it is false, as well as a first-hand case study supporting this position.

Myth: A building envelope can perform effectively on its own without any help from the HVAC system. Continue Reading No Building Envelope is HVAC Failure-Proof

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

As the building and construction industry continues to come out of the hibernation that has been the norm since 2009, it unfortunately appears that it’s déjà vu all over again when it comes to water-related building failures. As new buildings are being constructed, the same design and construction deficiencies of the past are being repeated, leading to (often catastrophic) mold and moisture problems.

 

It may seem somewhat unbelievable that the industry still finds itself making these same basic mistakes time after time. After all, preventative solutions to these issues have been understood and well-published for many years.

 

Continue Reading Design and Construction Amnesia: We Have Lost our Minds and it is Causing Catastrophic Mold and Moisture Building Failures

Performance criteria for the window do not always mean that the same criteria are required for the window unit and all of its accessories – like subframes.

 

Specifiers mistakenly assume that the performance criteria indicated for the window unit itself applies to the entire assembly, including accessories. This can be problematic, particularly if the accessories are a critical element in the water resistance of the assembly (e.g. subframes and receptor systems). Designers typically indicate stringent performance requirements for the glazing system but fail to properly design or detail the interface between the glazing and adjacent construction. Field testing typically includes this interface at the test pressures specified for the window and leakage is common. Differentiating between window and interface leakage is difficult. Operable window and door components are not required to be tested in as stringent a manner as fixed components; however, specifiers often indicate the wrong test procedures and/or field testing is performed erroneously using the wrong procedures, resulting in false test failures.

Three major changes will impact the success of construction in Florida over the next decade. These changes began as trends during the last decade and have now evolved into requirements for construction professionals. This requires one to consider the risks of potential moisture problems and determine how to mitigate against these risk on the project. These risks are due in large part to changes in building code and how the industry is viewing the products that are being used in “green construction.”

 

  • There is a drive to certify products as “green” and this has substantially increased the risk of moisture problems when certain products are used. Knowing the anatomy of these products will help the construction professional alleviate this risk.
  • Green initiatives have become codified and are required now by code these for projects. It is a critical skill to be able to know the parts of the code that result in the greatest risks for causing moisture problems.
  • As the construction industry shifts from primarily a USGBC LEED® rating credit system to other rating systems like Green Globes there is a risk that comes from the introduction of confusion in the “green” marketplace and the construction industry. This confusion affects the contractor’s’ ability to communicate the needs and costs of green construction. This lack of communication can lead to budget and schedule overruns that are costly. The skilled professional will need to know which rating systems are critical for projects in humid climates and how to communicate the requirements of those rating systems to clients.

Continue Reading How to Avoid Moisture Problems When the Requirements and Practical Applications of Green Collide

The mission of designing high-performance buildings that promote sustainable objectives has led to new success stories but has also revealed vulnerabilities for potential mold and moisture failures.

 

The interaction between a building’s HVAC system and envelope creates an unusually high-risk area. Any deficiency in either system can cause dramatic, building-wide moisture and mold problems. Through the emergence of high-performance buildings combined with the use of certain new green products, designers and contractors have inadvertently created high-risk buildings when, in fact, the goal should be to develop high-performance buildings with the lowest possible risk of failure.

Continue Reading New Online Course Demonstrates How to Design and Construct High-Performance, Low-Risk Buildings While Avoiding Catastrophic Mold and Moisture Problems

In our work as forensic architects and engineers, we are regularly involved in litigation over stucco failures, including hotels and high-rise condo complexes. (For this article, ‘stucco’ refers to traditional portland cement plaster direct-applied to a masonry substrate, rather than using lath.)

 

Myths abound around stucco cracking. In truth, it is not abnormal to have some cracking with stucco, much of which can be relatively harmless. The key is paying attention to the types of cracks, and minimizing any significant issues that might lead to actual failure, including debonding, water intrusion, and mold problems. It is not a good idea to pack out stucco so thick it may end up debonding and falling on those Bentleys (and their owners) below.

 

Myth #3: Direct-applied stucco is easily packed out to meet a finished plane.

Continue Reading Stucco Myth #3: Direct-applied stucco is easily packed out to meet a finished plane

In our work as forensic architects and engineers, we are regularly involved in litigation over stucco failures, including hotels and high-rise condo complexes. (For this article, ‘stucco’ refers to traditional portland cement plaster direct-applied to a masonry substrate, rather than using lath.)

 

Myths abound around stucco cracking. In truth, it is not abnormal to have some cracking with stucco, much of which can be relatively harmless. The key is paying attention to the types of cracks, and minimizing any significant issues that might lead to actual failure, including debonding, water intrusion, and mold problems.

 

Myth #2: Control joints are required every 13.5 m2 (144 sf).

Continue Reading Stucco Myths: Myth #2 – Control joints are required every 13.5 m2 (144 sf)

In our work as forensic architects and engineers, we are regularly involved in litigation over stucco failures, including hotels and high-rise condo complexes. (For this article, ‘stucco’ refers to traditional portland cement plaster direct-applied to a masonry substrate, rather than using lath.)

 

Myths abound around stucco cracking. In truth, it is not abnormal to have some cracking with stucco, much of which can be relatively harmless. The key is paying attention to the types of cracks, and minimizing any significant issues that might lead to actual failure, including debonding, water intrusion, and mold problems.

 

Myth #1: Stucco on lath over CMU/concrete is superior to direct-applied
 

Continue Reading Stucco Myths: Myth #1 – Stucco on lath over CMU/concrete is superior to direct-applied