Follow the manufacturer size recommendations 2.
Measuring for pocket replacement windows.
Down the left side right side and the middle.
With helper set window into opening to check fit then remove it.
Pocket that exists between the outside and inside stops after the parting bead is removed.
New pocket replacement window should be about 3 16 to inch shorter than smallest measurement in opening.
This measurement should be between 3 5 inches and 5 5 inches.
To check your windows are in square alignment.
Measure from the high point of the sill of your window the surface closest to the inside of the window to the top of the window opening.
Again you ll need to take three measurements each extending from the top horizontal board.
Replacement windows are sold in a standard thickness to fit inside the 3 1 4 in.
Use the smallest of the measurements to determine the width that surrounds the window.
Measure the height from the head of the window top fixed frame piece to the windowsill bottom fixed frame piece as with the width take three measurements.
Measure the windows jamb depth.
Tips for measuring windows.
One at the left side one at the center and one at the right side of the window.
This is the pocket the sill will fit into.
Measure the window s width in three places top middle and bottom of the window.
Record the shortest measurement this ensures that the new window will fit.
If the pocket is outside of this range modification to the pocket may be needed and you should call an expert.
Measuring for replacement windows begins with determining that the corners of the existing window frame are square.
Standard window sizes vary but you can be sure that replacements you order will have 90 degree corners.