Window Installation Done Right
Doing everything to ensure a leakproof job? If you don’t include the housewrap, use a sill pan, and flash the flanges, the work is far from watertight.
Installing windows properly involves several key factors, but has one crucial goal: keeping moisture away from the wall cavity to prevent decay from occurring. Builder Rob Moody and his crew use an installation procedure that requires a bit more time and a little extra money for materials, but they believe their process is cheap insurance for a big investment. By using housewrap and pan flashing, then integrating the window with the proper substrate materials, Moody is able to get windows installed and feel secure that they won't allow water into the house. This article includes a sidebar by contributing editor Mike Guertin, who writes about the extra attention required for proper installation of windows that use mechanical flanges.
From Fine Homebuilding197
, pp. 54-59