Moisture and humidity from an indoor pool can damage not only the internal building materials, but also penetrate the interior cavity of the pool structure (between the interior wall and the exterior wall of the pool room). Without the proper vapor retarder, moisture from the pool can migrate to these areas as air moves from the warm inside side of the pool room to the cooler outside air side. Mold, rot, fungus, premature internal structural failure, rotting, and insulation deterioration are some of the problems when vapor retarders are not installed or penetrate after installation.
Building and construction materials play an integral role in moisture control and moisture migration
Vapor barriers are often overlooked in the design stages, forgotten about, not installed, or installed incorrectly. Green Board, Dryvit, various other “boards”, foil faced insulation, and other types of sprayed-in-place urethane foam insulation are not considered vapor barriers, nor are they generally recommended. There are very few acoustic panels made to withstand moisture stratification in an indoor pool. Suspended ceilings are discouraged as they become moisture traps in swimming environments. Many of these types of materials have been used in the past with extremely negative results; they are not bulletproof when it comes to moisture damage. Therefore, with an effective vapor retarder, good insulation, negative pressure, and a properly designed pool room dehumidification system; moisture damage can be prevented at the design/build stages.
What materials constitute a vapor barrier?
Generally, vapor barriers for an indoor pool are materials that do not allow moisture to migrate beyond surface areas into the structure. These are typically 8, 10, or 12 mil heavy plastic sheets. The effectiveness of barriers in preventing moisture migration is rated by “permeability ratings.” The higher the permeability index, the less moisture the barrier will penetrate into the pool hall structure. It is recommended that the barrier have a permeability index of 0.10 or less when used in an indoor pool.
If an existing indoor pool and vapor retarder cannot be installed below finished surfaces, other materials that may be considered vapor retarders are waterproof paints or other types of paints or sealers (check with a paint specialist or building professional). ). We also recommend reviewing the ASHRAE Vapor Barrier Guidelines for additional information.
Where is the Vapor Barrier in an Indoor Pool?
Applying your vapor barrier is also critical to preventing moisture damage. Vapor barrier for all swimming pools is installed on the walls and ceilings below the finished surface (or the warm side of the pool room). We recommend 10-12 mils. Seamless vapor barriers will be installed wrapping around the entire pool room. The barrier is overlapped and sealed at the joints. Once installed, prevent barrier penetrations (ie, top hat recessed can lighting is not recommended; surface mount all lighting). All mechanical and electrical contractor penetrations must be sealed hermetically. It is recommended that the wall vapor barrier be sealed (not just overlapped) to the ceiling vapor barrier.
Care should also be taken when installing insulation around the pool cover, as poor insulation leads directly to higher energy and operating costs. Be aware that gaps in the insulation create “cold spots” that also promote moisture condensation. If negative pressure is not designed in, moisture can and will migrate to areas outside of the pool room. A properly designed indoor pool will ensure attention to these three important aspects of moisture migration and control.