Why Buildings Fail
An alarming number of new buildings suffer from moisture and mold problems. The risk of failure is highest in—but not limited to—cold, temperate, warm-humid, and hot-humid climates. The debate on why some buildings fail and others do not, as well as who is responsible for these failures and how to fix them, rages on. Instead of being aired in architecture schools and at engineering society meetings, however, this debate goes on in courtrooms and mediation hearings, among highly paid expert witnesses and lawyers—not among people who should be preventing failures, but among those who are rewarded by their occurrence.
The building industry seems baffled about the prevalence of building failures. Many wonder why the rate of building failures is not declining despite better technology, increased training, and more sophisticated building systems. It is not due to indifference or ignorance. We know we can prevent buildings from failing because we can fix them once they do fail. The primary reason we are not coming to grips with this far-reaching problem is simple: the design professionals entrusted with building performance are not receiving adequate feedback on the performance of their previous buildings.
Without that feedback, we do not know why some buildings work well and others do not, despite being apparently designed the same way. Metrics may say that the industry did a good job, yet clients keep complaining about building failure and the construction litigation business keeps growing. Until architects and engineers receive better performance feedback, they will have neither the ability nor the incentive to change.
WHAT’S THE SOLUTION?
Buildings fail because of misinformation about failure. We tend to believe that if our clients do not complain, there is no problem. The reality is that some buildings are at risk without our knowing it. Moreover, many within the industry do not know what puts those buildings at risk, nor how to minimize that risk inexpensively and effectively. Fortunately, building success does not depend on spending more money on design and construction. Instead, we need to spend differently to achieve consistently better results.
One solution is engaging in moisture expert building commissioning, which provides institutional knowledge to the development team about the critical components necessary for good building performance. This knowledge is especially valuable during the design phase.
Success using this strategy depends on three elements. Design professionals need to:
Establish specific written design and construction guidelines at the project’s inception and distribute them to all relevant parties. These design requirements must go beyond the traditional vague performance language, which has proven ineffective, and extend into a series of “do this” and “don’t do that” recommendations.
Use periodic peer reviews throughout design and construction to compare results against the original design and construction guidelines.
Implement proper start-up techniques for the building systems (including heating, ventilation, and air-conditioning [HVAC] systems and building envelope components) to verify that the building is operating correctly before it is occupied. This step should include detailed pressure mapping of the building to confirm that it is properly balanced; extensive monitoring of environmental conditions and moisture levels during the first year of operation; and water spray testing of key envelope components, such as windows and doors. Regardless of the choice of testing types, these tools must measure the performance of the architectural and mechanical components in combination—not separate from each other.
Intelligent decisions must be made at each stage (design, construction, and operation) of a project’s life if problems are to be avoided and costs controlled. If this is done properly, redundant components or procedures will be eliminated, decreasing the incidence of problems without affecting the construction cost and schedule.
Protecting Indoor Air Quality
Indoor air quality (IAQ) problems in facilities are overwhelmingly caused by moisture intrusion. When moisture enters and remains in a building’s envelope and its occupied space, mold begins to grow—and so do complaints from occupants about their health and comfort.
Newly constructed buildings exhibit a disproportionate share of moisture and mold problems because significant errors made during the design, construction, or operation of a building often manifest themselves as moisture problems during the building’s first cooling season. While this article addresses the errors that occur in new construction, the concepts also apply to the remediation of problems in existing buildings.
Rather than following a topic-based organizational structure (for example, HVAC design and wall system design), a peer review should be organized by design and construction phase. It should define the roles and responsibilities of the design team, contractor, and building owner (particularly of commercial and institutional facilities) and integrate moisture avoidance-related technology into the process of designing and constructing a building. These steps should make it easier for architects and their design and construction teams to prevent mold-related problems, for which causes--and therefore keys to prevention--usually lie early on in the design process.
To ensure that the recommendations in a peer review do not impose undue financial or scheduling burdens on the development team, we are endorsing only those that are most important in avoiding future moisture problems and that have proven themselves on our own projects over the past 25+ years.
Decisions made daily during design and construction phases often occur without a full understanding of their ramifications. Beginning the process with a set of prescriptive guidelines, implementing strategic reviews at critical phases, and ending construction with a sound HVAC system start-up and performance verification procedures will improve architectural decision-making and ultimately prevent future moisture-related building problems.
This article is brief by design and is not intended to provide comprehensive architectural, engineering, and mold remediation data available elsewhere, nor to substitute for professional expertise. LBFG encourages owners, designers, and contractors to work together to improve decision-making. This is especially needed as architects participate in more construction work (e.g., through design/build) and as builders provide more pre-construction services.
While this article is geared primarily towards commercial construction, the fundamental issues are similar, if not identical, in residential construction and can be dealt with in a similar fashion.
Most of the cases we work with and mention relate to preventing moisture intrusion and mold problems in warm-humid (aka hot-humid), or rainy climates, which covers a significant portion of the United States. The majority of our case studies relate to air- or vapor-borne moisture. Mold and moisture problems associated with plumbing leaks or groundwater intrusion are usually more easily identified and resolved.
Today, there is unquestionably more information about the causes of and solutions for moisture and mold problems than there has been in the past. We encourage you to convert the information presented here into usable knowledge that can be applied to create problem-free buildings.