202 at the top 120 and sides 130 of the window 100 assuming that there is no failure in the window itself the moisture enters at these locations under the nailing flange 170 while the sealant applied under the flange 170 should help prevent this gaps or cracks in the sealant are inevitable the moisture that seeps under the nailing flange 170 will enter the space 310 between the window 100 and the rough opening 200 at this point the foam 320 that was installed all the way to the nailing flange 170 will interfere with the ability of the moisture to find its way down to the sill 230 the problem is that the foam material 320 is permitted to fill the space 310 all the way to the nailing flange 170 at some point the foam 320 will form a blockage against the nailing flange 170 and prevent any further downward movement of the moisture toward the sill 230 in addition since the foam insulation 320 is never perfectly formed cracks and gaps in the foam 320 form passageways that permit the water to move toward the interior 240 of the rough opening 200 in fact once the foam insulation 320 has formed a blockage with the nailing flange 170 the only place for the water to go is toward the interior of the building there the water remains leading to water damage and molding issues the present invention.