Condensation forms when warm air touches a cold surface. Condensation in a pole barn can damage building materials. So to control it, you need insulation, a vapor barrier and adequate ventilation.
How a Vapor Barrier Controls Condensation in a Pole Barn
A vapor barrier reduces the amount of vapor that gets into a building from the source of the moisture. Install it on the warm side of the insulation. This is usually the inside. However, in a hot, humid climate, the vapor barrier may go on the outside of the insulation.
Why Vapor Pressure Matters
Vapor pressure drives water vapor through a vapor barrier. Also, vapor pressure changes with temperature and humidity. A vapor barrier reduces vapor movement, but it does not completely stop it.
If the vapor pressure gets too high, any vapor barrier will stop working. This is why you also need insulation and ventilation.
Understanding Perm Ratings
Manufacturers rate the facing material of a vapor barrier on a scale called “perm.” So the lower the perm value, the better the vapor barrier facing.
Ventilation Needs Depend on Use
The amount of ventilation you need depends on how you will use your pole barn. For example, on a farm, ventilation can reduce odor. In addition, you can ventilate a garage with vented soffits and ridges.
Construction Steps That Cause Condensation
Pole barn construction can also contribute to condensation problems. It is common to pour a concrete slab after the pole barn goes up, using the grade boards as forms. Then, in the winter, crews often use a propane heater to cure the concrete.
As a result, this can create enough water vapor to get through the vapor barrier. That leads to condensation in a pole barn.