Obtaining Correct Measurements for Replacement Wood Window Sash

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If the frames are intact but the sash are missing, follow these instructions:

I.  Measuring Double-Hung Window Frames to Fill with a Pair of Sash:

1. Obtain sash thickness measurement.  Measure the width of the sash channels.  It is best to measure the width of the outside (upper) sash channel as the blind stop and the parting stop are fixed in their spacing, whereas the inside stop is adjustable and therefore may not provide an accurate measurement.  For standard 1-3/8" check-rail sash, the sash channels should be 1-7/16" wide.

2. Measure width of frame between pulley stiles.  Take measurements at top, center, and bottom of frame.  The sash should be made 1/16" to 1/8" narrower in width than the smallest of the width measurements obtained.  If there is a significant difference in the width measurements, consider repairing the frame first so that the pulley stiles will be parallel prior to measuring for sash.

3. Obtain window opening height measurement.  The height measurement must be taken at the proper location on the sill in order to obtain the correct height measurement.  The correct height measurement is taken from the underside of the window head to the sill at the inside of the parting stop.   This dimension is typically in even inches for eastern standard windows, For single-light sash windows, the sash opening height is typically 6" more than the combined overall glass height for both sash.  Example:  Glass height = 24", sash opening height = 54" (4'-6")

4.  Determine Parting Stop Size.  The parting stop fits into a groove ploughed into the pulley stiles, and its purpose is to separate the upper and lower sash by providing the inside of the upper sash channel and the outside of the lower sash channel.  Standard Eastern frames have 1/2" wide parting stops that project 1/2" out from the face of the pulley stiles.  (the portion of the parting stop that fits into the groove does not affect the sash.  The actual parting stop may be 1/2" x 3/4" or 1/2" by 7/8" in section, but the projection out from the frame should be 1/2" in any case.)  If your parting stops have different dimensions, make note of your parting stop width and projection.