How to Measure for a Window Sash Replacement Kit

Lead Image for How to Measure for a Window Sash Replacement Kit
  • 1 hours
  • Beginner
  • 1-30
What You'll Need
Pencil and paper
Tape measure

A window sash replacement kit includes replacement parts for the affixed vinyl, aluminum, or wooden framework around the window. The sash of a window fits into the window frame and is held in place by a sliding track. The kit provides you with a new sash and jamb hardware for the window you would like to replace. New sashes can be primed and painted prior to installation in order to match the color of the home.

Windows are one of the sources of energy loss, and replacing a window sash with a replacement kit can help you conserve energy rather than replacing the entire window. They will make your home more energy-efficient, as well as improving the architecture of your home. There are three materials you can replace the old sashes with, they include wood, vinyl, or aluminum. To maintain a classic appearance on old homes, wooden sashes are recommended. Vinyl or aluminum are often used on newer built homes.

Measuring the Width of the Window

Measure the width by placing your tape measure from the wood surface to the wood surface on each side of the window. You will want to measure the top, middle, and bottom to ensure they are the same width apart. Remove any jamb liners temporarily to avoid any pulleys, weather-strips, or stops in the window frame. Record the measurements with a pencil and paper.

Measuring the Height of the Window

Open both sashes slightly and place the tape measure between the sashes. Start at the top, measure from the head jamb to the foot of the sill on the window. Make sure to eliminate any stops within the window that might obstruct a precise measurement. Start at the sill, and measure to the top of the sloped sill on the exterior side of the lower sash. Measure the height at the left, middle, and right sides of the entire window. Record the measurements you have taken with a pencil and paper.

Measuring the Angles of the Window

You will want to confirm that the existing window is square by measuring both diagonals on the window. If the measurements are more than ¼” out of proportion, then an out of square adjustment in the width of the measured window must be made. To determine the adjustment, a plumb line is made from each corner to the sill or head of the window using a level. Use a plumb line that falls within the opening of the window, measure the out of square adjustment. Subtract this measurement from the smallest width measurement. Record this width measurement as the smallest width adjustment measurement with paper and pencil.

Now that you have your measurements, you can then bring the paper with your measurements to a hardware store to order your replacement window sash. If you find that your window is not level, then installation may become difficult, and additional trim work may be needed. If you’re measuring more than one window sash, be sure to keep track of the measurements by noting where the window is located above or below each window’s measurements.