100
ADDRESSING MOLD GROWTH ON LUMBER DURING CONSTRUCTION: FACTS, MYTHS, PERCEPTIONS,
AND SOLUTIONS.
B. Kollmeyer, M. Canright, A. Bendush, S. Harney, Forensic Analytical, Rancho Dominguez Hills, CA.
Situation. This case study presents a discussion of experiences arising in the course of several investigations involving fungal growth on lumber encountered during the construction process—the condition commonly referred to as “lumberyard mold.” Problem. Lumberyard mold is a condition frequently encountered during the construction process. During the construction process, various stakeholders raise the questions regarding the presence of this growth and how is should be managed—questions that hygienists are frequently called upon to answer. Current guidelines addressing mold growth in buildings do not specifically address the subject of lumberyard mold and significant variability exists within the industrial hygiene community regarding appropriate responses—from characterization of the growth, to potential hazards, to remediation recommendations. Resolution. This case study discusses the approaches taken in conducting lumberyard mold investigations and the challenges encountered in making recommendations and resolving conflicts. The presentation focuses on identifying methods of characterization, data interpretation, and supporting decision criteria through the use of existing references and professional experience. The results of a survey of fungal growth observed and sampled on lumber for sale at various retail outlets is presented in the context of understanding the difference between typical and atypical lumberyard mold growth and the implications for making risk management decisions. Benefit. This presentation will provide hygienists with methods of assessing and resolving issues associated with lumberyard mold that have proven effective in addressing the concerns raised by stakeholders. It will provide an awareness of pitfalls encountered in addressing this issue and identify resources to support decision making. The end goal of this presentation is to apply real-world experiences that support a move toward greater consistency in how hygienists deal with this vexing issue.
101
THE IMPACT OF HISTORIC RESIDENTIAL FRAMING STYLES ON MOLD GROWTH ASSESSMENT AND
REMEDIATION.
P. Hand, B. Woodhull, Clayton Group Services Inc., Edison, NJ.
Identifying and evaluating the cause and origin of mold growth in older residential properties can be challenging for the industrial hygienist. Consultants and contractors should be aware of various types of residential construction techniques, and the design and construction of the residence before recommending or performing remediation in older homes. This presentation focuses on residential home construction techniques, and how specific framing techniques used in American history can impact and complicate the process of evaluating water damage and mold growth in older homes, as well as recommendations for subsequent mold remediation. This presentation discusses the chronology of frequently utilized framing techniques in American history and how the construction styles can influence mold inspection and remediation techniques. The presentation will feature the use of photographs to illustrate framing styles such as timber frame, balloon frame, braced frame, and the modern platform frame techniques. The presenter will discuss these historic construction features and provide information to assist the industrial hygienist in identifying these features in the field. Suggestions to assist in avoiding common problems associated with the presence of these construction features when planning mold remediation procedures will be discussed.
102
MOLD DURING NEW BUILDING CONSTRUCTION IN THE NORTHWEST: FIVE CASE STUDIES.
M. Rose, Clayton Group Services Inc., Seattle, WA.
Balancing modern construction scheduling requirements with the needs of moisture prevention can be especially difficult in a precipitation-heavy climate such as the northwest United States. Nearly vertical Gantt charts are now commonplace on the construction manager’s wall, which often make difficult the task of protecting buildings under construction from extended periods of rainfall. This presentation summarizes the consequences (and cleanup techniques) of unplanned moisture incursion into five different building types under new construction. We identify similarities among the causes of mold growth between the five case studies, which include material selection, material protection, vulnerable architectural features, and inadequate ventilation. We also identify similarities in assessment practices used and the reasonableness of cleanup methods recommended by the hygienist. To prevent similar problems in the future, construction managers need to be apprised of the potential consequences of inappropriate material selection, inappropriate material installation schedules, recommended material protection techniques, and ventilation requirements.
103
CASE STUDY—WHAT MAKES SOME HOTELS SUSCEPTIBLE TO MOLD GROWTH?
P. Haas, D. Zehnter, Morse Zehnter Associates, West Palm Beach, FL; R. Morse, Morse Zehnter Associates, Poestenkill, NY.
This is a case study of a building in North Carolina that was inflicted with a confluence of design and maintenance problems to create an extraordinary mold problem. This building was beset by so many different problems that this case study illuminates a variety of different causes of mold amplification. The investigators were summoned to this building when the mold growth behind the vinyl wall covering had completely consumed the mounting adhesive so the wall covering was being held in place with thumb tacks and staples. This case study will describe: building envelope problems, chilling of walls due to improper locations of air conditioning equipment, improper control of bathroom exhaust fans, vinyl wall covering, low moisture capacity building construction, and misplaced vapor barriers. Corrective measures will be described and proper construction techniques for mixed climates will be illustrated.
104
BUILDING SHRINKAGE AND MICROBIAL DAMAGE: PLUMBING FAILURES AND WATER
INFILTRATION FROM JOINT FAILURES.
G. Crawford, F. Boelter, M. Cornwell, Boelter & Yates Inc., Park Ridge, IL.
This paper presents case histories of situations where water infiltration of interior wall cavities in newer mid-rise and high-rise buildings resulted in mold growth. When conducting mold investigations involving extent of damage and species, it is also essential to be able to identify the cause and origin of the moisture responsible for the mold problem. In the cases presented, an understanding of construction technology was essential. Mid- and high-rise buildings built with reinforced concrete framing and concrete block bearing walls can experience vertical shortening during the early life of the structure. As the concrete cures, a certain amount of shrinkage occurs at each level which can add up to a significant dimension in taller buildings. In structures with concrete block bearing walls the same phenomenon can occur. If the moisture content is too high when the blocks are placed, significant shrinkage can occur as the building is enclosed and the blocks dry. Buildings constructed with pre-cast floor systems can also experience differential movements as structural components are loaded and camber is reduced over time. These structural movements can create stresses in the mechanical components that are not subject to the similar rates of shrinkage, most notably the plumbing system. Unlike faulty construction or a system failure, concrete shrinkage is not a building defect but rather an accepted consequence of the construction materials and techniques used. Given the rigidity of plumbing systems, damage to soldered joints and plastic welded joints are most severe when the building shrinks. Cast iron with leaded joints is usually the least affected. This paper examines preventive and corrective measures, construction techniques, concealed plumbing leakage, and mold issues associated with several types of structural system movements in mid- and high-rise buildings.
105
THE EFFECTIVENESS OF ANTIFUNGAL AGENTS AS INHIBITORS OF MOLD GROWTH ON GYPSUM
WALLBOARD.
N. Zimmerman, V. Perez, Purdue University, W. Lafayette, IN.
Microbial growth on indoor surfaces has the potential to lead to indoor air quality problems. The purpose of this study was to test three antifungal agents, thymol, benzoate, and sorbate, as inhibitors of fungal growth on wallboard. After some initial experiments to determine the most effective method to initiate the growth of mold on wallboard, large sheets of wallboard (2’ x 2’ or 1’ x 2’) were placed vertically in troughs of water to a depth of 1” and located in basements with high humidity and known mold activity. A variety of concentrations of the antifungal mixture as well as of thymol alone were applied to the test boards. The boards were evaluated approximately every seven days using a semiquantitative scaling method which consisted of a growth range from 0 (0% surface coverage) to 4 (100% coverage) and a density range from A (very thin, barely noticeable) to D (very dense coverage). Without the inhibitor on the wet control boards, growth was seen within 14 days. At the initial antifungal agent concentrations tested (thymol–0.2%, sorbate and benzoate–1%), some mold inhibition continued for 28 days compared to the untreated controls. At three times the initial concentrations, the antifungal effectiveness was greatly increased, with no fungal growth on the saturated boards for over three weeks compared to ratings for the control samples ranging from 2–4 and B–D. Thymol alone was also tested, at both three and six times the original strength, and was almost as effective. Storing treated boards for a month prior to saturation still provided significant antifungal activity for over two weeks. The results of this research indicate that application of the thymol, benzoate, sorbate mixture to the surface of wallboard shows promise as a means of reducing mold exposure from wet wallboard.
106
EFFICACY OF CHLORINE BLEACH IN KILLING AND BLOCKING ALLERGIC REACTIONS TO MOLD
ON CONTAMINATED BUILDING MATERIALS.
J. Martyny, K. Pacheco, R. Harbeck, E. Barker, M. Sills, S. Arbuckle, L. Newman, National Jewish Medical and Research Center, Denver, CO.
The use of disinfectants for mold remediation has been discouraged, since simply killing mold has not been proven to reduce the antigenicity of mold spores. In addition, the ability of disinfectants to kill mold on contaminated environmental surfaces has been in question. We tested the hypothesis that the spray application of a dilute sodium hypochlorite solution on environmental surfaces will kill mold and significantly reduce mold antigenicity and allergenicity. Aspergillus fumigatus was grown in an incubator on three different types of building materials. The surfaces were then treated using a 1:10 dilution of commercial chlorine bleach (sodium hypochlorite solution), a Tilex® solution, or distilled water controls, applied for 10 seconds using a spray bottle. Surface mold and debris were then mechanically removed from the boards after the spray had dried. Fungal material extracted from the boards was cultured to determine viability, and examined using light microscopy and scanning electron microscopy to detect morphological changes. Extracts of material removed from the boards were tested for Aspergillus fumigatus antigenicity using ELISA and for allergenicity by skin prick testing of individuals allergic to Aspergillus fumigatus.
We found that the application of either sodium hypochlorite solution or Tilex resulted in significant killing of Aspergillus fumigatus mold on the environmental surfaces, and produced observable changes in the appearance of conidia. The antigenicity of the fungi and fungal structures recovered from treated boards, as measured by ELISA, was substantially reduced compared to controls. Skin prick testing demonstrated loss of skin test reactivity to mold in 5/6 individuals tested with sodium hypochlorite-treated fungal extracts. We conclude that the spray application of sodium hypochlorite onto mold-contaminated building materials can kill mold, cause morphological changes to the conidia, and reduce the allergic properties of mold. The use of sodium hypochlorite solutions in mold remediation projects may therefore be beneficial.
Posted May 30, 2005