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ASCE 24-14 for Flood Loads
Published in Syed Mehdi Ashraf, Structural Building Design: Wind and Flood Loads, 2018
Wet floodproofing relies on the use of flood damage-resistant materials and construction techniques in areas of structures that are below the elevation required by ASCE 24-14 by intentionally allowing the areas to flood. In wet floodproofing, the structure is allowed to be flooded, but it is anchored to prevent flotation and has flood vents, or permanent openings, that allow water to flow in and out of the structure without damaging the structural elements. The hydrostatic pressure on the interior and exterior sides of the structure is equalized. Wet floodproofing is not conducive if the flood duration is greater than 24 hours. Wet conditions lead to damage of structural elements of the building and to the formation of mold and mildew. Utilities, appliances, and contents are placed at higher locations or are protected in place. Flood damage-resistant building materials are used for those parts of the building that will be flooded. Automatic shutoff valves are installed on sewer and fuel lines.
Paint and Protective Coatings
Published in Ryan Cruzan, Manager’s Guide to Preventive Building Maintenance, 2020
Mildew: If not properly treated before painting, mildew on old paint will continue to grow on the surface of new paint. To properly treat mildew, first the source of moisture must be corrected. If mildew is growing on the exterior surfaces, consider cutting vegetation to allow sunlight to reach the area. Mildewed surfaces should be treated with a 25% solution of sodium hypochlorite household bleach left on for twenty minutes before rinsing. Mildew resistant paints offer some protection against new mildew growth. However, if moisture issues are not addressed, mildew will eventually return.
Improving Ventilation
Published in Ed Bas, Indoor Air Quality, 2020
Air Distribution - Clean indoor air must be distributed evenly in indoor spaces so that all occupants have access to fresh air of relatively uniform thermal comfort, humidity, air velocity and quality. In addition, perimeter areas should be properly ventilated during the winter (heating season) to keep these areas warm and dry to prevent condensation. The resulting moisture can damage walls, wall-coverings and drapes, while providing conditions that allow mold and mildew (harmful bacteria) to flourish (see Chapter 6 for more on moisture and humidity).
Probabilistic assessment of the potential indoor air impacts of vent-free gas heating appliances in energy-efficient homes in the United States
Published in Journal of the Air & Waste Management Association, 2018
Gary K. Whitmyre, Muhilan D. Pandian
The relationship of indoor relative humidity to indoor sources of water vapor, outdoor relative humidity, and building factors (e.g., air exchange rates, heat exchange) is complex. Relative humidity is defined as the percent saturation of air with water vapor at a given temperature. The warmer the air, the greater is the mass of water per cubic meter required to achieve a given relative humidity level (Dunn 1951). The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) has recommended an indoor relative humidity range of 40–60% as being desirable based on comfort; the U.S. Environmental Protection Agency (EPA) has recommended a range of 30–60% for indoor relative humidity based on comfort. During the heating season, cold “dry” air is often brought into the home via normal infiltration/air exchange (Liebmann 1965). Cold air entering the home in winter through infiltration is then heated, which results in a higher capacity to contain water vapor. A relative humidity level greater than 70% can result in active growth of mold and mildew on indoor surfaces (Kalliokoski et al. 1993; Morey et al. 1984). Indoor environments commonly contain a variety of mold and mildew species, including Penicillium, Aspergillus, Cladosporium, and Fusarium species (DeKoster and Thorne 1995; Lipkowitz and Novarra 2001; Pasanen, Niininen, and Kalliokoski 1992).