Depending on the approach and materials used, one barrier may act as more than one control layer.

• The weather barrier can also be the air barrier
• The vapour barrier can also be the air barrier
• The thermal barrier can also be the air barrier, vapour barrier, and/or weather barrier

No matter what material is used for the air barrier, it must always be continuous throughout the home. All seams, junctions, and penetrations must always be sealed and mechanically fastened.

There are several different approaches that can be used to install control layers. The approach used will determine the materials and placement of the control layers. The following section looks at several different approaches for installing the control layers. Please note that the approaches are commonly named after the air or vapour control layer, but all control layers are used in these approaches.