Step 1: Watch an Overview Video

Step 2: Gather Your Materials and Tools

Materials and Tools:

pocket replacement window
tape measure
4- to 6-inch shims
screwdriver
safety glasses
level
hammer
latex painter's caulk
wood shims
1- to 1-1/4-inch finishing nails
exterior wood insert or flat vinyl trim

Step 3: Remove the Old Window

A fully assembled pocket replacement window fits easily into an existing opening.

Carefully remove old window sashes and clean frame. Save inside stops for new window.

Make sure there are no obstructions in opening; scrape away old caulking and debris.

Step 4: Check That the Window Fits

New pocket replacement window should be about 3/16 to 1/4 inch shorter than smallest measurement in opening. (Follow the manufacturer size recommendations.)

With helper, set window into opening to check fit, then remove it.

Step 5: Add Caulk and Check for Square

Run continuous bead of caulk along outside stops where window will rest.

Put window back into opening and raise and lower sashes to check for square.

Tip:If diagonal measurements corner to corner are within 1/8 inch, window is square.

Step 6: Add Shims and Insulating Foam

Shim four corners and check window for plumb. Place, DO NOT HAMMER, shims.

Caulk gap on sides and top.

Insert screws in pre-drilled holes in window frame.

Place corner bead of sealant around perimeter of window frame where new frame contacts original window frame.

Apply insulating foam sealant between window and rough opening.

Re-install inside stops.

Caulk inside perimeter.

On exterior, fill gap under new frame with insert or install flat vinyl trim, if necessary.