How To Replace Your Windows | Ask This Old House

Step-by-Step Tutorial: How to Measure and Install a Replacement Window

Part 1: Measuring for the Replacement Window

1. Measure the Width:

   • Measure from jam to jam or against the trim on the back side of the stop bead.
   • Record the width measurement at the top and bottom of the window.
   • Ensure all measurements are consistent.

2. Measure the Height:

   • Measure the highest point of the sill against the back of the stool.
   • Use a plumb tape measure to ensure accuracy.
   • Record the height measurements on both sides.

3. Check for Squareness:

   • Hold the tape tight against the stop bead and check the diagonal measurements.
   • Ensure the diagonal measurements are equal to confirm the window is square.

Part 2: Understanding the Replacement Window

1. Exterior and Interior Features:
   • Exterior: Composite material wrapped in vinyl.
   • Interior: Maple (available in oak or pine).
   • Weatherstripping on the bottom and sides for a tight seal.
   • Insulating features like emissivity coating for energy efficiency.

Part 3: Removing the Old Window

1. Prepare for Removal:

   • Score the paint where the stop bead meets the trim using a utility knife.
   • Remove the stop bead carefully and save it for reinstallation.

2. Remove the Old Sash:

   • Pull out the parting bead at the top.
   • Remove the jam liners by pulling and pushing against them.
   • Use a putty knife to release the jam liners and remove the old sash.

3. Remove the Storm Windows:

   • Unscrew the storm windows from the frame.
   • Remove any old paint to ensure a snug fit for the new window.

Part 4: Installing the Replacement Window

1. Prepare for Installation:

   • Apply a bead of caulking around the perimeter and two beads across the sill.

2. Install the New Window:

   • Place the bottom of the window in first and balance it.
   • Check the spacing on each side and adjust as needed for a tight fit.
   • Use plastic shims provided by the manufacturer to hold the window tight.

3. Check for Squareness:

   • Install screws through the window into the jamb and slide shims over the screws.
   • Tighten the screws to ensure the window is square.
   • Measure the diagonals to confirm squareness and make adjustments if needed.

4. Final Steps:

   • Seal around the perimeter with caulking.
   • Reinstall the stop bead.
   • Smooth out the caulking with wet paper towels for a clean finish.

5. Exterior Finishing:

   • Apply a good bead of caulking around the perimeter for weather tightness.

Congratulations! You have successfully measured and installed a replacement window following these step-by-step instructions.