b'barrier and siding is key. In replacement, as the photosillustrate, removing an old door can either destroy theintegrity of the old sill, or expose the fact that there was nointegrity in the first place. Filling the old sub sill with mor-tar or even the same thin set as used with tiling floors, can create the sealed, level and strong sub sill a successfuldoor installation requires.3. Proper Sill Pan/Drainage. In heavy winds,water can literally blow under the door and up and over the back part of the doors operating track. In wind above150 mph the water can climb upwards of 2 inches andover the sill into the room. The first inclination is to seal the front of the operatingtrack to prevent water from penetrating under the trackand into the room. Doing so prevents another key functionof the sill under the track - drainage. Proper techniquerequires a sill pan (see illustrations) to be placed under the track to allow water than may get into and round the opening to drain out. Creating the proper balance betweenprotection from wind blown rain and sill drainage is difficult, but necessary.Some manufacturers make a two piece sill/track to accomplish the goal, but in most instances sealing thefront edge of the track, but leaving two 2-inch gaps in theseal, will protect against the window blown water, but allowdrainage from the sill pan when necessary. Judgement canalso be used consideringlocation. If the doors are set backon a large porch, there is less worry about window drivenrain. If the doors are near a corner of a balcony on a highfloor, there is more concern for blocking wind-driven rain.Summary: Make the sill smooth and level, use a sill panand use clips/straps or conventional installation as shownin the window section. Be as mindful of flashing, sealing,and mounting hardware as for window products. Finally, as with most door products, be sure to follow manufacturers instructions as they have most likelydesigned their sill and track systems to comply with therequirements of the doors application.Window Fitters Guide to Window Installation1082020 AWDI, LLC Do not reproduce without permission'