Remove Sidelight Window
Put a drop cloth on the floor under the sidelight window. This helps protect the floor from debris when removing the trim and sidelight.
Check the trim on on the inside of the sidelight panel to determine how to pry it off the sidelight frame. Wide trims usually pry away from the glass and thinner trims pry away from the frame.
Insert a flexible putty knife between the top of the side trim and the sidelight frame. Hold the putty knife at an angle with the handle pointing up. Tape the top of the putty knife handle with a hammer and guide the putty knife blade down the length of the trim. This separates the trim from the frame. If you have wide trim, insert the putty knife blade between the glass and trim. Keep the blade at an angle and sliding down the glass.
Repeat the process for the opposite side. Once the side trims are off the sidelight, remove the top and bottom trim in the same manner. Scrape away any excess putty from the inside of the frame with the putty knife. Remove the staples securing the glass in place with a pair of needle nose pliers. The staples are in the frame and extend over the glass.
Insert the putty knife between the top of the glass and the frame, if you have insulated glass. A screw is on each side securing the glass in place. Twist the putty knife slightly to push the glass toward the opposite side so you may see the screw shank. Cut through the screw shank, even with the frame, with a keyhole hacksaw. Keyhole hacksaws are small hacksaws with the front of the blade protruding from the tool. Repeat for the opposite side.
Ask a helper to push on the top of the sidelight from outside while you guide the glass out of the frame. Remove the old caulk on the inside of the frame where the glass sits with the putty knife.
Replace Sidelight Window
Apply an 1/8-inch bead of silicone caulk to the inside face of the sidelight window frame with a caulk gun. The caulk forms a weatherproof barrier and cushion between the new glass and the frame.
Insert the new sidelight window into the frame. Press it firmly into the opening, starting at the bottom and working up.
Tap 2-inch long staples into the side of the frame with a hammer, every 12 inches. The side of the staple should be over the glass by 1/2 inch.
Add an 1/8 inch bead of silicone caulk around the perimeter of the glass with the caulk gun. Press the top and bottom trim pieces against the glass. Tap the trim into place with the handle of the putty knife until the trim is flush with the frame.
Hold the center of the side trim and press the top of the trim into the frame. Bend the bottom of the trim into the frame and push the center against the frame. The side trim pieces lock into the space between the top and bottom trim. Tap the trim to firmly seat it flush with the frame.