Foundation Research Series

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1 PREVENTING LOSSES FROM MOISTURE AND MOLD DURING CONSTRUCTION Foundation Research Series Foundation of the Wall and Ceiling Industry 803 West Broad Street, Suite 600 Falls Church, VA Phone: (703) Fax: (703) Web Site:

2 THE FOUNDATION OF THE WALL AND CEILING INDUSTRY 803 West Broad Street, Suite 600 Falls Church, Virginia (703) (voice) (703) (fax) Please accept this contribution to the Foundation for General Donation Memorial in Memory of In Honor of DONOR INFORMATION Name Company Address City, State, ZIP FOUNDATION CONTRIBUTION $25 $50 $100 $500 $1,000 $ Payment Options (Please make payment in U.S. funds only.) Check (enclosed) Credit Card: Visa MasterCard American Express Account Number Exp. Date Name as it appears on card Signature for Payment (Credit card payments may be faxed to (703) no cover sheet required) Date

3 PREVENTING LOSSES FROM Prepared for the Foundation of the Wall and Ceiling Industry by the Chelsea Group, Ltd. One Pierce Place Suite 475E Itasca, IL Phone: (630) or (800) Fax: (630) Web Site: MOISTURE AND MOLD DURING CONSTRUCTION 2003 Foundation of the Wall and Ceiling Industry. All Rights Reserved. No part of this publication may be reproduced in any form by any electronic or mechanical means, including information storage and retrieval systems, without permission in writing from the publisher. Published by The Foundation of the Wall and Ceiling Industry, 803 West Broad Street, Suite 600, Falls Church, Virginia, (703) Foundation Research Series Price: $10.00 April 2003

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5 Contents Table of Contents Preface Introduction Scope Using This Document Background: Preventing Losses from Moisture and Mold Section 1. Practical Steps in Wall and Ceiling Construction Manufacture Supply and Distribution Transportation Delivery and Storage Pre-Installation Condition of the Building Installation Wet Processes and Finishing Protecting Installed Work Delivery of Completed Building Warranty Resolution Section 2. Special Issues and Challenges Documentation Moisture Measurement Testing for Mold Presence Building Dynamics That Impact Moisture and Mold Section 3. Contingency Planning for Water Intrusion and Mold Events Advance Planning for Contingencies Remediation of Problem Situations Section 4. Checklists References Bibliography Foundation of the Wall and Ceiling Industry Page 3 Preventing Losses from Moisture and Mold During Construction

7 Preface Preface Foundation of the Wall and Ceiling Industry In the late 1970s, there was a clear recognition among industry leaders for the need to unite and expand the educational and research activities available to contractors, manufacturers, distributors and the public, in general. At the time, there were many issues facing the industry from a national energy crisis to injuries in the workplace, to unsafe buildings occupied by the public. In response to these issues, the Foundation of the Wall and Ceiling Industry was formed in 1977 with the following mission statement as an IRS designated non-profit 501(c)3 corporation to pursue educational and research activities benefiting the industry and the public at-large: The Foundation s mission is to be an active, unbiased source of information and education to support the wall and ceiling industry. To fulfill this mission, the Foundation owns and maintains the largest independent library serving the wall and ceiling industry, provides educational scholarships for those pursuing careers in engineering, construction and design, provides research support to industry inquiries and publishes research papers. This paper provides means and methods to avoid moisture intrusion and mold damage during new construction, and is intended for the wall and ceiling construction industry, including manufacturers, contractors and building owners and managers. It is a compilation of research that encompasses a review of available literature on the subject and interviews with subject matter experts. The literature research included Internet searches on various topics, a review of articles and guidance documents in the libraries of both the Foundation of the Wall and Ceiling Industry and Chelsea Group, Ltd. It is not intended to provide design guidance or to serve as a training manual for mold assessment and remediation. The goal is to provide readers with an understanding of how to prevent mold problems and handle mold complaints when they do occur. The subject matter experts who were formally interviewed are listed in the reference section. Both the Foundation and the Chelsea Group, Ltd. express our gratitude to those involved in this process. To obtain additional copies of this research paper or to learn more about the Foundation of the Wall and Ceiling Industry, please contact The Foundation of the Wall and Ceiling Industry 803 West Broad Street, Suite 600 Falls Church, Virginia Phone: (703) Fax: (703) info@fwci.org Foundation of the Wall and Ceiling Industry Page 5 Preventing Losses from Moisture and Mold During Construction

9 Introduction Introduction Scope This document provides a basis for wall and ceiling construction contractors to prevent physical losses from water and mold damage in the normal course of their work. Preventive actions and procedures are explained for each step in the process from the manufacture of the materials to the completion of the building. Additionally, the document reviews special issues and challenges that cut across all aspects of a construction project, including documentation, moisture measurement, testing for mold presence, and building dynamics as they relate to moisture and mold. Finally, the document provides information to support contingency planning for instances in which moisture and mold problems occur in a construction project, including both advance planning and a review of remediation steps. The document does not provide the basis for a contractor to assume the role of a mold remediation expert or contractor. Using This Document Preventing Losses from Moisture and Mold During Construction builds on the findings and recommendations of Mold: Cause, Effect and Response, published by the Foundation of the Wall and Ceiling Industry in March Use of this document assumes the reader s familiarity with the earlier publication. The materials presented in Preventing Losses from Moisture and Mold During Construction derive from the published scientific literature, trade publications and from extensive interviews with industry leaders. The state-of-the-art relating to moisture and mold in buildings changes rapidly. Scientific foundations, particularly as they relate to mold in buildings, continue to evolve. Use of this document should be supplemented with advice from experts familiar with updates to science and opinions on appropriate actions and procedures. References to industry standards published by advisory organizations are for illustrative and educational purposes. Actual project requirements are determined by state and local building codes, established industry practices, project documentation and manufacturer s requirements. On specific projects, the wall and ceiling contractor must verify compliance with state and local building codes, manufacturer s requirements, and project documentation. Throughout the document, reference is made to various manufacturers of products, product literature, contractors or experts in the field. These are used to reflect research on industry opinion or to provide concrete examples of the points being made. Reference to a product does not imply any endorsement of the product. For quick application of information contained in the body of this document, a group of 10 checklists is presented in Appendix A with brief instruction for their use. The reader is cautioned to use these checklists only after gaining a thorough understanding of the issue. This document is intended for educational purposes and is not a substitute for expert, professional guidance in specific situations. Foundation of the Wall and Ceiling Industry Page 7 Preventing Losses from Moisture and Mold During Construction

10 Introduction Background: Preventing Losses from Moisture and Mold The following materials are derived from Mold: Cause, Effect and Response. Readers familiar with that document may safely proceed to the next section. While mold is nothing new, its prolific growth in some buildings and fears of adverse health effects are a more recent development. Are these concerns justified? Who is most at risk for having health problems as a result of mold? Are all molds toxic? What molds are considered toxic molds? Where and when does mold grow in buildings, and why does it seem there is more mold growing in buildings today as compared with 20 or 30 years ago? What can be done to clean up mold, prevent it from coming back, and reduce liability in case of mold infestation? Answering these questions requires realizing that mold growth in buildings and its relation to health effects is not as simple as is presented in news reports and litigation. Answering these questions also require looking at why mold is becoming a more prevalent problem in buildings, where mold grows and why, and what it is about mold that has prompted so many concerns. Fungi are naturally occurring organisms that make up approximately 25 percent of the earth s biomass and play an essential role in the processing of decaying organic matter into substances that are necessary for sustaining plant and animal life. 2 Mold is a generic term that is used to describe a wide variety of visible fungi. Throughout this this paper, the terms mold and fungi are used interchangeably. Buildings are dynamic environments, affected by geographic location, climate, heating, ventilating and air-conditioning (HVAC) system design and operation, types of building materials used in construction and finishing, moisture intrusion, pest colonization and human activities. To grow, mold needs a nutrient source, appropriate temperature and moisture. Are molds really toxic? There is no simple yes or no answer to this question. Although much has been made in news reports and in recent litigation about the health effects from exposure to mold, especially with regard to Stachybotrys chartarum, this topic is somewhat controversial as there is little scientific or medical evidence that demonstrates that some molds are indeed toxic. But at the same time there is consensus that some fungi species can produce mycotoxins, which are considered to be toxic to humans and other animals. Opinions differ, however, about whether exposure to these mycotoxins produces disease. Harriet A. Burge, Ph.D., a recognized expert in mycology, said that such reports are anecdotal and lacking sufficient data to document a clear connection between exposure and disease. 3 Successful remediation and restoration of a building or home with mold can be accomplished without taking drastic steps as reported by some news media. While there are no set standards, a number of organizations have provided guidelines. According the New York City Department of Health Guidelines for Assessment and Remediation of Fungi in Indoor Environments, the goal of a mold remediation is to remove or clean any contaminated materials in a way that prevents emission of fungi Foundation of the Wall and Ceiling Industry Page 8 Preventing Losses from Moisture and Mold During Construction

11 and dust contaminated with fungi from leaving a work area and entering an occupied or non-abatement area, while protecting the health of workers performing the abatement. 4 Success of the remediation process can be judged by the following: Introduction Visual inspection to ensure all of the contaminated substrate is removed. Confirmed by sampling, including outdoor/indoor ratios. Results of surface sampling should be similar to other well-maintained buildings or on construction and finishing materials in the same geographic area. Ability of people to re-occupy the space without complaining of adverse health effects or physical discomfort. If mold should begin to grow again, then likely the source of water or moisture has not been found or adequately controlled or eliminated. These sources must be addressed to keep fungi from reestablishing colonies. 5 For mold to grow, it needs moderate temperatures, nutrients in or on the substrate, fungal spores that settle on the substrate, and sufficient moisture. For all practical purposes, all of these conditions, except possibly moisture levels, are present in nearly every building, so the answer to preventing mold growth is controlling moisture. 6, 7 Foundation of the Wall and Ceiling Industry Page 9 Preventing Losses from Moisture and Mold During Construction

13 Practical Steps in Wall and Ceiling Construction Management of moisture represents a challenge at each step of wall and ceiling construction, from materials manufacture to finishing the building. At each step, actions by the party responsible for the materials, their installation, and the building in which they are installed determines whether there will be a moisture or mold related loss. While contractors are not responsible for all aspects of moisture or mold in buildings, action on items within their control can result in a reduced risk of damage. Manufacture Section 1 Manufacturer Role in Loss Prevention. The manufacture of wall and ceiling materials results in the production of dry product that must be protected from environmental moisture throughout its life. Manufacturers typically measure moisture content for quality control during the baking and curing process for gypsum board. However, there is no industry standard for moisture content limits prior to distribution. 8 Key actions to protect wall and ceiling materials under the control of the manufacturer include the following: Verify moisture content is within specification for the material during production Handle and store at the manufacturing site to keep the material dry, protected from liquid water and high humidity conditions. Wrap and protect the finished product for shipment. Expectations of Subsequent Protective Actions. Manufacturers expect that the distribution and transportation of their product will maintain the protections they have put in place. Many manufacturers cite ASTM standards that state, All materials shall be delivered in the original factory sealed, unopened packages, containers or bundles bearing the brand name, applicable standard designation and the name of the manufacturer, or the supplier for whom the product is manufactured. 9 Manufacturers typically specify the conditions that their materials will withstand, including moisture- and mold-related issues. For example, some ceiling product warranties specify acceptable onsite conditions, including storage locations, level of building enclosure, temperature and humidity ranges, and functionality of HVAC systems. 10 Some gypsum board manufacturers specify the acceptable moisture content of the wood framing substrate before installation. For example, one manufacturer recommends that the moisture content of wood framing should not be in excess of 19 percent at the time of installation of their drywall products. 11 New Technology and Improved Methods. Manufacturers have added products and continue to innovate with new ways to prevent moisture and mold problems related to the use of their materials. Concerns about mold have resulted in products that are less susceptible to moisture damage such as one wallboard product line that incorporates an inorganic backing. 12 Other products have antimicrobial characteristics included in their manufacture. 13 Foundation of the Wall and Ceiling Industry Page 11 Preventing Losses from Moisture and Mold During Construction

14 Section 1 Manufacturers are also taking steps to package their products to arrive dry-on-site, with edge taping of individual pieces, or the practice of wrapping pallets in various plastics and other protective materials. It is important to note that these precautions are meant to protect the materials during transit. A technology opportunity exists for the development and application of protective products that allow materials to breathe while protecting them from water intrusion. Supply and Distribution Distributor Role in Loss Prevention. Wall and ceiling materials need to be dry and ready for transportation at an optimum time during the project. Suppliers and contractors should agree on the order ship date so materials get to the site at the appropriate time, keeping flexibility in the process to adjust to actual progress. Key actions to protect wall and ceiling materials under the control of the distributor include the following: Maintain protection of the wall and ceiling materials from moisture during storage and warehousing. Verify that the materials will be ready to ship by the date that works with the project schedule, with flexibility for delays. Ensure the proper packaging and on-loading of materials. Distributors and suppliers need to follow manufacturer guidance on storage and handling of the product. Storage of drywall and ceiling materials prior to shipment to a construction site must, at a minimum, protect those materials from rain or flooding. Storing materials under roof or protection with tarpaulins typically accomplishes this. The Gypsum Association Specification GA-216, Application and Finishing of Gypsum Board states that all materials shall be kept dry, preferably by being stored inside a building under roof. When it is necessary to store gypsum board and accessories outside, they shall be stacked above ground, properly supported on a level platform, and fully protected from weather and direct sunlight exposure. 14 Materials will seek equilibrium moisture content with their environment. Control of ambient relative humidity for storage is not indicated since the materials must eventually equilibrate with the environment at the construction site. However, wet materials should not be shipped, delivered or 15, 16, 17 accepted. As much as possible, leave the shipping date to be determined based on the actual progress of the project. The distributor or supplier and contractor should agree to establish an acceptable trigger and signal for shipping to begin. Optimally, this can be scheduled so that materials arrive in time for installation, allowing sufficient time on site for the materials to come to equilibrium moisture conditions on the site as well as time for contingencies resulting from inspection and replacement of damaged materials. Expectations of Subsequent Protective Actions. Distributors and suppliers expect transportation companies to maintain the packaging and protections that are in place at the time they leave the distribution center. Some distributors also specify that carriers must tarp their trucks front to back, Foundation of the Wall and Ceiling Industry Page 12 Preventing Losses from Moisture and Mold During Construction

15 Section 1 and top to bottom. 18 They expect that any problems with the materials as they arrive on site will be handled promptly so responsibility can be affirmed. Distributors and suppliers have similar expectations to those of manufacturers with regard to contractors protecting the materials on the construction site. New Technology and Improved Methods. Inventory control systems are making advances in scheduling that can ease the delivery timing pressures. Handheld wireless devices are being used on construction sites to quickly and efficiently order materials. 19 Increased efficiencies translate into materials being stored on-site for shorter periods of time, limiting exposure to potential moisture damage. Transportation Carrier Role in Loss Prevention. The carrier will transport the wall and ceiling materials from the distribution center to the construction site while maintaining the packaging in original condition. Experienced carriers will typically be prepared for the large and heavy packages or the need for gentle handling. However, moisture control has not typically been viewed as part of shipping responsibilities for construction materials in the past. 20 Actions that will protect materials during transportation include the following: Specify transportation requirements clearly, including responsibility for protection from potentially damaging environmental conditions. Verify that the mode of transportation, packing and route will not compromise the manufacturer s specification for conditions that the materials will withstand. Educate transport crews to monitor the packaging for tears and to handle materials to avoid moisture or mold damage. Expectations regarding the carrier s responsibility for protection of materials from moisture and mold damage need to become part of normal discussions among the contractor, supplier and transportation companies. While breakage and similar problems are commonly recognized in such discussions, moisture has only recently become an issue. Clear allocation of responsibility in advance of shipment and proper documentation of the condition of materials at each stage can help prevent losses. Modes of transportation can become critical in certain climate conditions or events. For example, materials shipped a few miles on a sunny day may get by with the load simply secured to a flatbed truck. However, that approach would likely result in wet and moldy materials if they were shipped cross-country in winter. Enclosure and proper packing become critical as the risks of rain or snow increase, and those risks increase with the elapsed time for shipping. 21 Manufacturer s recommendations for handling represent the minimum requirements, and greater care is warranted where harsh environmental conditions threaten the integrity of the materials. Foundation of the Wall and Ceiling Industry Page 13 Preventing Losses from Moisture and Mold During Construction

16 Section 1 With materials properly packaged and protected, visual inspections for tears in waterproof materials and other failures in protections from moisture are necessary throughout the transportation process, particularly if any transshipment is involved. Documentation of the results of inspections and quick action to repair any problems found are key to a dry, clean delivery. Expectations of Subsequent Protective Actions. Carriers will expect that the site will be properly prepared and staffed for delivery to protect the materials from moisture and mold. Carriers should reasonably expect inspection of the materials at the time of delivery by the contractor and rapid alerts to any problems with the materials as delivered. Delivery and Storage Contractor Role in Loss Prevention. Materials that arrive on site must be dry and mold-free in order for the project supervisor to take possession of the shipment. Responsibility for receiving shipments varies from site to site, but having a proper system for receiving materials and taking them to storage will help prevent damage. Once materials are stored, they require continuing attention during the entire storage period. Actions by the wall and ceiling contractor that will protect materials during delivery and storage include the following: Inspect materials on the truck to make certain that all protective packaging is in place, and to look for damaged materials. Inspect materials as they arrive, documenting and rejecting wet or moldy materials. Prepare the set-down area so that it is dry. Define a quarantined area for damaged materials if they cannot be returned immediately. Educate construction crews in how to handle materials and to keep them dry. Inspect stored materials frequently for signs of wet conditions, potential tarpaulin leaks, condensation or visible mold. Materials should be inspected visually prior to storage. They should arrive in the original factory sealed, unopened packages, containers or bundles bearing the brand name. 9 Wet or moldy packages should be rejected and returned or segregated from the clean materials for resolution. Water on the surfaces of the packages should be wiped dry to avoid adding moisture to storage areas. Any materials that appear during handling to have water or mold damage should be separated from clean materials to eliminate situations where mold spreads to clean materials in the storage area. 11 Read and follow the manufacturer s directions for material storage. The area where materials will be placed should be well prepared prior to set-down. It should be a fully enclosed, hard floored, dry Foundation of of the Wall and Ceiling Industry Page 1614 Preventing Losses from from Moisture and and Mold Mold During CONSTRUCTION Construction

17 Section 1 location or, at a minimum, a location with a watertight roof near where the materials will be applied. Enclosed protection from the weather is required for the storage of all gypsum products. It is important to store materials off the ground to avoid wicking of water from the floor or drying concrete, and to allow ventilation to avoid condensation. Drying concrete releases nearly 50 gallons of water per yard of concrete during the curing process, which takes more than 30 days. 22 Use risers, skids or dunnage at the site to keep the bottom of the bundle of materials at least 4 inches off the floor, with clear airflow under the bundle. The materials should rest flat on wood risers spaced no more that 28 inches apart and no more than 2 inches from the end of the board to avoid sagging or warping of the boards. Locate stored stocks of gypsum products away from heavy-traffic areas on clean and dry floors in the centers of the largest rooms to prevent damage. 11 Materials that are stored where rain or construction process water could fall on them should be covered with tarpaulins that are heavy enough to withstand any wind or other harsh conditions. While the tarpaulin should be weighted down on top to prevent it from blowing away, it should not be tight against the sides of the stack because this can reduce air circulation and hold moisture inside the sheeting. When tarpaulins and other temporary protective measures are used, the materials should be checked frequently for evidence of moisture damage or mold growth. 23 If materials are stored on site for extended periods of time, they should be checked at least weekly to make certain that the materials have not been moved and that the tarpaulin is still intact. If they have been moved, they should be inspected immediately for previously unseen damage. Inspect the materials periodically thereafter for water damage or mold growth. For these inspections, remove the tarpaulins and examine the materials. Materials that are designed to repel water, such as glass or vinyl, should not be allowed to remain wet during storage, as mold can grow on water resistive materials or on dust and debris accumulated on those materials. Expectations of Subsequent Protective Actions. The wall and ceiling contractor expects the general contractor and other subcontractors to take steps necessary to be certain that their actions do not result in wetting materials stored on site. Roof and wall penetrations must be closed to protect materials from weather and wet construction practices in adjacent areas. Temperature and humidity conditions should be managed where practical, both for the acclimation of the materials and protection from wetting. Use of unvented, fuel-burning heaters for drying actually releases water vapor to the air, which may condense in or on the materials. 11 Several means, including desiccant or mechanical dehumidifiers, ventilation fans and electrical or properly vented heating equipment can accomplish drying. Installing and starting up drying or dehumidification equipment on site slightly earlier than installation allows the contractor to slowly bring materials to the appropriate equilibrium moisture content. 22 Foundation of the Wall and Ceiling Industry Page 15 Preventing Losses from Moisture and Mold During Construction

18 Section 1 Pre-Installation Condition of the Building Contractor Role in Loss Prevention. An examination and documentation of the building s condition prior to the installation should be done to ensure that all surfaces that come in contact with wall and ceiling materials are dry and the building is dried-in. Walls or ceilings should not be installed over wet or moldy foundations, floors, studs, ceilings or structural elements. The work area should be isolated from wet processes such as fireproofing, and existing wet-applied materials should be dried to specification. Roof and wall penetrations should also be protected from the weather before installation begins. Key actions to protect wall and ceiling materials under the control of the contractor include the following: Inspect the work area and immediate adjacent areas for wet conditions, and the potential for leaks or condensation, dirt and debris, or existing mold. Inspect site for completion of dry-in (the ability to close all openings to the outdoor environment and prevent water entry). Do not start installation until all wet or moldy conditions are corrected, and all moisture sources are controlled. Document any substandard conditions beyond the contractor s control. Recommended industry standards call for certain conditions to be met prior to the installation of wall and ceiling materials. 9 For example, the standards call for the appropriate size, strength and trueness of substrate materials, such as steel or wood. These standards do not directly address core issues that relate to mold or moisture. However, prevention of losses for mold and moisture can be greatly improved by inspecting for and correcting problems in the substrate. A clean wall cavity prior to installation will reduce the number of mold spores from dirt and debris left in the project area. Large objects need to be removed, and the area needs to be swept. It is important that the wall or ceiling areas then be vacuumed prior to installation to remove as much construction dust as possible. 24 Leaks and condensate drips represent a major source of moisture and mold problems. The wall and ceiling contractor should verify and obtain documentation relating to factors that can damage their work. Plumbing and mechanical contractors should pressure test their installed systems prior to the installation of wall and ceiling materials. Similarly, the mechanical contractor should inspect insulation on chilled water piping, particularly at joints and valves, and other potential plumbing condensation points. The substrate or framing on which wall and ceiling materials are applied can be a source of moisture and a potential cause of mold growth. When wood framing is used, one wallboard manufacturer recommends verification that the framing is dry, suggesting that moisture content should not be in excess of 19 percent. 11 When concrete masonry unit (CMU) construction is used, manufacturers recommend that the wall structure provide a sufficient thermal and moisture barrier to avoid both Foundation of the Wall and Ceiling Industry Page 16 Preventing Losses from Moisture and Mold During Construction

19 wicking of moisture through the CMU and condensation from thermal bridges, such as uninsulated steel studs, that reach the interior wall or ceiling materials. 25 Wall and ceiling materials should not be installed over conditions that may lead to future moisture- or mold-related losses. Expectations of Subsequent Protective Actions. The contractor should communicate and document problems that have been identified in the pre-installation inspection and cleaning to the general contractor or owner, as appropriate. The identified problems should be resolved prior to the installation of wall or ceiling materials. New Technology and Improved Methods. Experience in remediation of mold damaged buildings has led to the introduction of a number of coating products that can be used on substrates that are at risk for mold growth. These products include various chemicals that can be sprayed onto the substrate or framing to kill the mold spores or make the surface inhospitable for the early stages of 26, 27 mold growth. Installation Section 1 Contractor Role in Loss Prevention. During the job, the supervisor needs to establish a daily routine to check and document several details. The following key actions by the wall and ceiling contractors will help reduce the potential for damaged materials: Inspect the work area at the beginning of each day for mold, water intrusion and/or dirt. Respond to problems identified during inspections or pointed out by the crew and make sure they are resolved before the walls and ceiling areas are closed up. Follow recommended industry standards on placement or spacing of materials to prevent moisture intrusion. Complete end-of-shift checks to make certain that protective measures, such as keeping windows and doors closed, have been implemented. Routine inspection of the site to confirm that conditions remain acceptable for installation of wall and ceiling materials is a critical element in a successful project. Leaks, floods and condensation can all appear as problems mid-project, even if prior inspections have been problem-free. The earlier these problems are detected, the lower the cost to repair. Recommended industry standards call for an acclimation period that must be factored into scheduling. Industry standards for gypsum board call for an acclimation period of 48 hours under an ideal temperature range prior to the application of bonding and joint treatments. 9 Use of heating and cooling equipment during construction is a complicated issue. Recommended industry standards specify that the work area for wall installation be well ventilated. 9 Outdoor air for ventilation may introduce issues of humidity and temperature control. Measures should be taken to ensure that the gypsum board stays above dew point temperature (see Building Dynamics That Impact Moisture and Mold, page 26). As mentioned in the section on storage, direct-fire heating Foundation of the Wall and Ceiling Industry Page 17 Preventing Losses from Moisture and Mold During Construction

20 Section 1 systems, such as propane or kerosene heaters, should be avoided, since they add moisture from combustion. Cooling a space for worker comfort during finishing, but shutting those systems off at night to save energy, may create cold surfaces on which moisture from untreated outdoor air can condense and cause wetting of materials over night. Ceiling tile installation should occur after the HVAC system stabilizes humidity levels in the work area, with one manufacturer describing the norm for installation as 70 percent relative humidity. 28 At the same time, HVAC systems need to be protected from construction dust and related problems. 29 HVAC systems should, at a minimum, be operated with filters in place. Industry guidance on installation of drywall includes recommendations on providing spacing of at least one half inch between the floor and the bottom of the gypsum board to prevent wicking of mop water or moisture from concrete flooring. 8 Further protection from wicking, as well as fire protection and acoustical benefits, can be achieved by applying a fire sealant bead between the floor and the bottom edge of the gypsum. 22 Common sense also dictates an effort at the end of each shift to secure the work area from potential sources of water or moisture by closing windows and doors and making certain other protective measures are in place. Expectations of Subsequent Protective Actions. The wall and ceiling contractor should inspect the site to review the job with the general contractor. The inspection should include documentation that the work is in good condition and dry with no visible mold present at the time it is handed off to the general contractor. By the conclusion of the site inspection, the measures necessary to protect the work from weather, wet processes and condensation should be made clear to the general contractor. The wall and ceiling contractor should expect the general contractor to take the steps necessary to protect the finished work and to take responsibility for repair if subsequent water or mold damage occurs. New Technology and Improved Methods. Manufacturers have made strides in providing products that have more flexible installation requirements. For example, one manufacturer of ceiling tile reports that they have a current product that can be installed without stabilizing indoor environmental conditions. In particular, this product is reported to be able to be installed while relative humidity levels may reach 99%. 28 Installers are cautioned to review and follow manufacturer s recommendations for installation conditions for the specific product they are using. Additionally ceiling installers are cautioned that the risk of mold growth increases if materials achieve and sustain equilibrium relative humidity above 70% for an extended period of time. 16 Wet Processes and Finishing Contractor Role in Loss Prevention. Drywall taping, finishing and plastering introduce moisture to the work area. Certain applications of drywall, plastering and ceiling material, such as use of adhesives or wetting for bending to curve the surfaces of the materials, also represent wet processes. In addition, there are other wet processes that may be going on in the same time frame or vicinity as wall and ceiling work, such as application of spray-on fireproofing or insulation. The wall and Foundation of the Wall and Ceiling Industry Page 18 Preventing Losses from Moisture and Mold During Construction