An indoor pool building is a hostile environment that is continually subject to high humidity and condensation formation. Humidity in the air will condense into a liquid when it reaches its dewpoint, and that can occur in both visible and hidden locations.
Vapor barriers and vapor retarding membranes are critical in the design and construction of an indoor pool facility. They prevent or severely limit the permeation of water vapor through walls, floors and ceilings where the condensation will be absorbed in insulation, limiting its effectiveness. The moisture can also cause structural damage such a rot and corrosion, wall cracking from freezing and damage finishes on wall surfaces.
Inside surfaces are subject to vapor migration and condensation when moist, warm, pool room air migrates to an adjacent space and comes in contact with a visible or concealed surface that is at or below the dew point temperature. Besides structural damage, the increase in latent load can burden the adjacent space mechanical system.
Vapor membranes must be installed near the inside surface closest to the pool room of the ceiling, walls, or floor. There must be no unsealed seams, cuts, cracks, penetrations, orvoids in the material, and vertical and horizontal seams must be overlapped and taped. All doors, windows and skylights need to have a high R-value and sealed from air filtration. Door and window frames should have thermal breaks, and structural steel beams must not go all the way through a wall above an exit door or window.
Penetrations degrade a vapor retarder’s effectiveness if it has a very low permeance, and perforations may lead to air leakage, which further erodes effectiveness.
Suspended ceilings are not suitable for humid pool room spaces, but if used, the cavity walls and cavity ceiling must have a continuous vapor membrane, with all seams and cracks thoroughly sealed, just like in the rest of the pool room walls and ceilings.
Water vapor retarders are classified as rigid, flexible or coating materials and are available in a variety of styles including thin sheets, coatings and materials of multiple layers. Water vapor retarders are classified as rigid, flexible, or coating materials. Rigid retarders include reinforced plastics and are mechanically fastened in place and are vapor-sealed at the joints. Coating retarders may be semi-fluid or mastic; paint or hot melt, including thermofusible sheet materials.
Four basic indoor pool principles to be aware of with regards to dealing with excessive-humidity problems;
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1.) Architecture
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2.) Air Distribution
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3.) Mechanical Equipment
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4.) Water Chemistry