b'This condition is significant because it will indicate TrapezoidWhile mostthat the upper corner of the window is not flat in openings have equal widthsplane to the opposite lower corner. This will render and equal heights down andthe new window contorted in installation.across the opening, occa-If it is a finned window, the fin will not rest flat on the sional an opening can beframe of the opening without pushing the window out wider at the top, or wider atof shape. This can impede operation. Worse might be the bottom. leaving the out-of-plane condition opening up one or This condition might become more corners to leaks. evident whenmeasuring theIf possible, you can use the Bulb Level on the face plumb and square, but aof the wall to determine if one side or both sides are trapezoidal effect can requireout of plane and by how much.Record all these a change in the width and/ordimensions on the specification sheet. height of the specified window, and therefore needs tobe recorded on itsCrownThis condition will appear in the sill where own on the specifi-the center between the jambs is higher than at the cation sheet.edges of the opening. Placing a window or door on a The specifiercrowned sill can cause the interlocks to not meet should considerproperly; the panels to not slide properly on a sliding the conditions window or door, or will impede the proper operation of the opening of a hinged door or window. to properly orderUse a Bulb Level to determine crown, and record the appropriatelocation of the crown, and measure how much the size of the edge of the level needs to be raised on either side of new window. the high point to create a level condition. Record Then the installerthese measurements to help in sizing and shimming should consider needs. all 8 conditions toBowThe opposite of Crown, a Bow will be aproperly prepare low spot between the jambs. As with a crown, ato install the newdepression can cause the sill of the window orwindow in adoor to deflect, and impede proper operation and plumb, square andsealing/locking. As with Crown, record location and planar conditionheight differences on either side of the depression. necessary for proper operation,Record these dimensions on a specification sheet. locking, and sealing.CROWN IN SILL UNLEVEL SILLBOW IN SILLCROWN BOW TRAPEZOIDWindow Fitters Guide to Window Installation29 2020 AWDI, LLC Do not reproduce without permission'