Why moisture & mold problems are likely

(By Norm Nelson, Richard Scott, George H. DuBose, August,9, 2010)

While green buildings have many positive benefits, there is also strong evidence to suggest a direct correlation between new products/innovative design and building failures.

Two strong characteristics of most green buildings are: 1) the use of innovative, locally-produced products and 2) the implementation of new design, construction, and operation approaches that are intended to reduce energy usage and be environmentally sound.

The intent of building green is unquestionably noble and good, and should be aggressively pursued. However, because of the dramatic change that this will present to the design and construction industry, its implementation will present new risks that are likely to be both legal and technical in nature.

Some of the legal risks are fairly obvious, such as the risk of not meeting a building owner’s expectation of achieving a certain level of LEED certification (i.e., implied or even written warranties). Other risks are more obscure, such as:

• Accepting the higher standard of care that a green building might present—what is currently considered “best practices” may now become the new expected “standard of care.” Most insurance companies exclude anything that exceeds the normal standard of care.

• Failing to recognize (or prepare for) the unknowns in cost and schedule impacts that a green building might present.

• The failure of new products to meet their promoted performance levels, which is more likely with new materials compared to proven materials found in traditional buildings.

Open celled foam insulation (especially materials that are bio-based) is being heavily promoted as a green product and is often described as hydrophobic. The fact is that most of them are highly moisture absorbent. These materials have a high potential for hiding moisture problems and decreasing the drying potential of envelope cavities—both potentially severe problems in buildings.

Moisture intrusion, whether bulk water intrusion through the building envelope or a relative humidity increase due to the heating, ventilating, and air-conditioning (HVAC) system, results in a large percentage of construction claims in the United States. Sustainable building practices, some of which are part of the LEED accreditation process, can increase the potential for moisture intrusion if not carefully considered and implemented. Examples include:

• Vegetative roofs, which are more risky due to the constantly wet conditions must be carefully designed, constructed, and monitored after construction.

• Improved energy performance through increased insulation and the use of new materials, which may change the dew point location in walls, resulting in damaging condensation and a reduced drying potential for wall assemblies.

• Reuse of existing buildings or recycled components, which may not be easily integrated to the adjacent new materials and could cause compatibility problems between these materials.

• Use of new green construction materials that have not been field-tested over time.

• Increased ventilation to meet indoor air quality (IAQ) goals that may unintentionally result in increased interior humidity levels in hot, humid climates.

• Building startup procedures, such as “building flush-out,” which could result in increased humidity levels and mold growth.

New green construction materials are entering the market at a staggering rate. Because many of these products help to achieve multiple LEED credits, designers working on green buildings are eager to specify these materials. The risk to contractors is that many of these new items are not time-tested, and designers often do not have the time to fully research their efficacy. If the new product fails, it may be difficult to determine if it is a design error, an installation error, or a product defect. Additionally, contractors must rely on subcontractors to install new materials that they are inexperienced in installing.

(http://www.greenlodgingnews.com /)

21 Topics for projects and presentations:

1. Development of nanotechnology in Russia.

2. Nanotechnology in civil construction.

3. History of green and sustainable buildings.

4. Advantages and disadvantages of green buildings.

5. Modern tendencies in green and sustainable buildings.