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EPA Moisture Control Guide 2013

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Page 74 of 144

www.epa.gov/iaq/moisture Implementing the moisture control features of the design consists of two essential actions to be dried before they can be used. For example, foundation materials need to be dry before some coatings and flooring can be applied. 1. Understanding the moisture control design features in detail and ensuring their constructability. The sequence of activities plays an important role in preventing moisture problems during construction 2. Ensuring the moisture control features are effectively installed. • Moisture-sensitive and moisture-absorbing material and equipment should be scheduled for delivery when dry, protected storage is available. Coordination between construction companies who are obligated to control moisture in buildings as specified in the construction documents and building designers (architects and engineers) will enhance moisture control in the building. The contractor should review the moisture-control elements of the enclosure and mechanical system designs and discuss them with the designer(s) at the start of the project. However, contractors, subcontractors, construction management personnel, commissioning agents, and owners frequently propose alternative details, materials, or equipment. It is important to note that these changes can lead to changes in the moisture control requirements of the building and must be included in moisture planning. This includes proposals made during the bid process; during the development and review of submittals; at initial meetings between the contractor, designer, owner, and construction management service; or during meetings to review submittals, construction progress, difficulties, and responses to problems that have arisen. The contractor is urged to read Chapter 2 of this document to become familiar with the moisture control guidance for designers. The construction documents can be compared with the design recommendations of Chapter 2. • Wet, porous materials should be dry before moisture-sensitive materials are installed or moisture-sensitive coatings are applied. • Moisture-sensitive materials need to be protected from the weather as they arrive on site. Measures to keep rain away from the materials may also protect them from damage by dust and wind. • It is preferable to enclose the building so it is weather-tight before the moisture-sensitive materials arrive. While this situation can be planned for smaller projects, it may not be possible for larger ones. In these instances, contractors may provide temporary shelter for materials and equipment stored on site. They may protect partially completed work with tarps, temporary enclosures, or temporary bulkheads at floor penetrations. For example, gypsum board, brick, concrete block and wooden materials can be wrapped in plastic, covered by tarps or plastic and stacked on pallets in well-drained areas. Some materials that need to be protected, such as brick and concrete masonry units, can be delivered wrapped in plastic. • The lower stories of high-rise buildings are often being finished while the upper floors are still open to the weather. This situation requires using upper floors as temporary protection by making temporary bulkheads at floor penetrations and draining floors to the perimeter. Increasingly, contractors also use dehumidification equipment to dry out buildings that are enclosed, but not yet air conditioned. Scheduling is an ever-changing target that requires juggling the schedules of numerous suppliers, subcontractors, supervisors and inspectors. This already daunting task can be further complicated by larger issues, such as changes in markets or disasters in other parts of the world, that might affect the price and availability of supplies. It is crucial that the materials required to control moisture in the enclosure and the equipment required to control humidity in the building arrive so they can be installed in the correct sequence. For example, the drain plane or air barrier within a wall must be installed before the wall is closed in; otherwise, proper installation becomes a matter of demolition and reconstruction. • In spite of the best efforts to keep material and equipment dry, accidents still happen and things do get wet. Brick and concrete block may have absorbed water before they were delivered or while they were stored at the site. Heavy wooden timbers may have been milled and installed while still green. The earthen floor of a crawlspace foundation is a large area of soil exposed to the weather right up until the overhead floor deck is installed. Some materials get wet accidentally because of rain or for other reasons. It is important to dry out any moisture-sensitive materials as quickly as possible. 68

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