b'Often the success or failure of window installation Formula: Dbegins with the proper measurements and opening Lstatus informationor lack of it. D L 2 - D S 2 = WD L = Longer DiagonalMost installers or measurers are trained and record D S = Shorter Diagonalaccurately the width and height of the opening.W= Width of Opening WThese measurements should be done with regard to The difference between the type of window and construction of the wall. the sum of the squaresof the measured diagonalsD SWhatever method is used and/or described, it should cannot be greater than be consistent between installers or measurers and the opening width. openings and wall construction. In this way, thespecified window is consistent and regardless ofExample 1: Opening 36" wide by 48" high. The Longwho measures and specifies, any installer workingDiagonal is 60-3/8" and the Short Diagonal is 60-for the company will have the proper window and 1/8". Squaring the Long Diagonal (60.375 x 60.375)expectations at the job site. No surprises. equals 3,645.14". Squaring the Short Diagonal(60.125 x 60.125) equals 3,615.02". Subtracting In addition to the width and height, there are 6them finds a difference of 30.12". The difference isother states or conditions of the opening that needless than the width of 36" so the opening is squareto be measured, observed, and recorded so that theenough to accept a window designed to fit a 36" x 48"natural (or otherwise) idiosyncrasies of the opening opening. are non ahead of time and can be accommodated inthe specification of the needed window or door, and Example 2: Opening 28" x 60". The Long Diagonal isso that the proper materials and tools for correction 66-3/8" and the Short Diagonal is 66-1/8". Squaringwill be known and provided at the job. the Long Diagonal equals 4,405.64". Squaring theShort Diagonal equals 4,372.50". Subtracting equalsSquare 33.14" which is greater than the opening width ofBecause some openings have become out-of-square 28". The opening is out-of-square enough to warrantover the years, it is important that the squareness consideration of a window 1/8" to 1/4" narrower of the opening be accurately measured. Measure the than a window designed to fit an opening 28" x 60".diagonals (upper left to lower right, and upper right to lower left) as accurately as possible from a point Levelinside the stool to a point against the inside stop at When installing a vinyl window, it is important thatthe header. Record the two dimensions.the sill on which the window is resting be level.Outof level sills can cause havoc in the operation of largeIf they are roughly equal, the opening can be windows, casement windows, awning windows, slid-assumed to be square. If they are not, then it isers, and even double and single hung windows.Thepossible that the opening is out-of-square enoughmain reason for this problem is that out of level sillsto cause the new window to be forced into anwill distort the frame to an out-of-square situation.out-of-square condition during installation. Imagine a sill that slopes and the sides of the windowIf the new window is forced out-of-square, the inter- are made plumb.By definition, the window framelock, sill and header seals can leak air and possibly will become a parallelogram where the header andwater. Also the cam locks will not operate correctly the sill will be parallel, and the sides will be parallel,and the window will wear out prematurely. but the sides will not be atright angles (90) to the sillDetermine Square by measuring the corner diagonals or header.This will make(upper left to lower right, and lower left to upper it nearly impossible for theright). Record both dimensions. The difference sash, which will be squarebetween them is the square condition. at the corners, to nestproperly, lock properly,If the diagonals are not equal use the followingand seal out wind andsimple equation. If the difference between your moisture properly.measured diagonals is greater than the allowablevalue, it may be appropriate to order a window 1/8 As the sash is forced intoto 1/4 smaller than indicated by your measured the out of square frame,width. This will allow the new window to be installed undue pressure will besquare in the opening. Then adequate sealing of the placed on the corners, theperimeter of the new window will complete thehardware, and even the 32 Sills can be 1/8 out of level & stillair-tight installation. glass and its seal. meet code. Some sills are even worse.Window Fitters Guide to Window Installation232020 AWDI, LLC Do not reproduce without permission'