There are two systems that work well on the outside of the house and have, almost by accident, the effect of blocking almost all air movement through the wall. (Caulking is not one of them and should never be used on the outside of the house beyond what is necessary to prevent rain and snow from entering the wall. We want to block the air but we must not block the escape of moisture.)
Exterior stucco allows the easy diffusion of moisture and, at the same time, does not allow air currents to pass through. In Western Canada it is an economical siding with this very convenient added benefit.
House Wraps are special sheathing papers that have the fantastic characteristic of blocking rain better than construction paper and letting moisture out of the wall while somehow virtually stopping air infiltration. It has been widely used in the place of the traditional black or brown building papers since the early 1980's and comes in large rolls that allow you to virtually wrap the house like a Christmas present. Despite a higher cost than building paper, its ideal characteristics for our condensation-troubled houses has made it the standard for new construction. It can be applied to the walls of an existing house whenever the siding is changed. It can be used on the cold side of insulation under floors both as an air barrier and as mechanical support. It can be used over insulation in the attic, both as an air barrier and wind protection for loose fill insulation.