Condensation & Building Damage

The architect and contractor must coordinate with each other to make certain the building is appropriate to enclose an indoor pool. Suitable materials and construction are crucial to ensuring the building envelope will perform properly.

The pool enclosure must be suitable for year round operation at 50% to 60% relative humidity and built as per the latest building codes.

Check the pool enclosure design (exterior walls and ceilings) for the proper vapor retarder location.

Dew Point Temperature

The designer must establish the space dew point temperature to know where to locate the vapor retarder in the wall.

From the table below one can see that a typical pool design of 82°F (28°C) 50% RH has a dew point of 61°F (16°C). This means any surface with a temperature BELOW 61°F (16°C) will condense moisture (e.g. condensation forms on a can of soda because the can's surface temperature is below the air's dew point).

Vapor Retarder

The purpose of vapor retarder is to block moisture from penetrating into a wall or ceiling where it will encounter a temperature below the dew point temperature and condense. The vapor retarder is the most important component in protecting a building from moisture damage. Failure to install the vapor retarder at the proper locations will result in condensation forming in the structure and all its consequential damage, including the possibility of structural decay and roof collapse. The vapor retarder must be sealed (taped) at all its seams and around all electrical outlets. We also recommend eliminating all electrical outlets on exterior walls.

Window Design

Special attention should also be paid to exterior-glass components such as windows and patio doors. Due to their low insulation values, windows are usually the building element with the lowest inside surface temperature. Even a triple pane window can have an inside surface temperature below the room's dew point. Supply air must be used for condensation control.

Thermal Bridging

All other building elements that create thermal bridges must be avoided or be blanketed with warm supply air to prevent condensation damage. Skylights are especially vulnerable to condensation because direct air supply to them is very difficult to achieve. Window frames and firedoors are also subject to thermal bridging.

Dew Point: The designer must know where it can occur

The Vapor Retarder must be installed on the warm side of the dew point temperature.

Condensation will occur on glass unless warm air is blown against it.