Poorly hung windows can lead to a host of problems: leaks, fogging, drafts and jammed windowpanes. Like roofing, window installations are multistep affairs that require specialized skill and layers of sealing materials. In the rush of boom-era construction, contractors scrambled to find qualified workers. And when high-quality materials became scarce, they cut corners to get the job done.
To properly install a weatherproof window, the sides and top of the window (called the head) must be sealed with a rubberized flashing material that looks like giant strips of colored tape. The sides are flashed first, and then the head strip is applied to further protect from top-down drips [source: Ueno]. The bottom of the window, interestingly, isn't sealed as tightly. The idea is that gravity will always draw water to the lowest point. By leaving the bottom of the window frame relatively "open," any water that collects in that area can simply drain out.
Homeowners Against Defective Dwellings (HADD) has received many reports of defective windows that were improperly installed without flashing or foam insulation that would protect against drafts. When moisture infiltrates a house, wooden materials become saturated and swollen, walls bulge and crack, mold grows, and homeowners fume.
Onto the next construction nightmare: basement flooding.