Some great strides have been made to enhance door and window installations. One of them is the use of house wraps and water infiltration. When building wraps first came into play they were marketed and first thought of as a wind or air barrier. Now we know, they also are great at shedding unwanted water away from the interior of buildings. To shed water out and away, you must install the house wrap correctly.
Start by wrapping the complete exterior of the building, even the gable ends
. Be sure to start at the bottom and complete everything in a "shingle" method of installation. This just means to start at the bottom and overlap everything as you work your way up. Gravity pulls water down the building and as long as everything is overlapped it should make it's way down to the bottom of the building and drip harmlessly to the ground.
When installing windows make what is called a "martini" cut in the window opening. As you can see the cut looks like an upside down martini glass.