Air Barrier Vs Moisture Barrier
This is a type of migration of water vapor.
Air barrier vs moisture barrier. Buildings which have a properly installed air barrier system can operate properly with a smaller hvac system as the mechanical engineer does not have to compensate for a leaky building. The key to moisture control is the control of air transported moisture. When this air moves from location to location due to an air pressure difference the vapor moves with it. Department of energy say that the term vapor diffusion retarders more accurately represents the goal of a vapor barrier.
Even at wind speeds of 5 mph a wall without an air barrier retains less than 40 of its original installed r values. Fire resist products are formulated for burn resistance and have passed the nfpa 285 test in many wall assemblies. A proper air barrier is one of the most important elements of a successful building enclosure and one of the most overlooked. Essentially air barriers minimize or restrict heat loss and gains through conduction.
Moisture barriers and vapor barriers are both building materials designed to prevent water from getting past the barrier. To increase moisture barrier protection ccw also provides a variety of flashing products for use with air and vapor barrier systems. An air barrier must also resist air pressure differences that act on them. In addition tyvek weather barriers help keep bulk water out to help protect insulation in walls of both residential and commercial buildings.
In some cases the reduction in mechanical equipment size and cost can also offset the cost of the air barrier system in addition to lowering utility bills. Vapor barrier is the more common terminology though organizations like the u s. In the strictest sense air barriers are also vapor barriers when they control the transport of moisture. This requires an air barrier system or air pressure control that may or may not be combined with an air barrier system.
There is a big difference between air transported moisture and vapor diffusion. Germain director of osb ewp quality and technical at lp building solutions. High performance air and water barriers resist air and water intrusion which reduces the amount of moisture vapor in the panels. Weather resistive barrier systems lead the fight against moisture penetration said brian st.