How to Install a Window on a Home With Vinyl Siding

Position the zip tool flat against the siding that needs removal, and hook the zip tool to the seam on the siding. Pull the zip tool down to release the seam of the siding. Use a hammer to pull and remove all nails from the nailing strip on the siding. Remove enough siding for the new window.

Measure the rough opening of the window. Measure the height of the window (on each side) and in the middle of the window. Compare all three of the measurements. If the measurements are different, you will need to cut filler strips to make the sills even and square, that is, even on all four sides.

Cut 6-inch wide strips of self-adhering waterproof membrane, or another type of waterproof material. Apply the first strip of membrane to the bottom of the window, overlapping the two sides, 3 inches on each side, and adhere it to the bottom of the windowsill. Cut the two sides of the window 12 inches longer than the sides of the rough opening, and adhere to each side of the window. Install the last piece of membrane to the top, overlapping 12 inches, and adhere to the top of the window opening.

Insert the window into the rough opening, resting the bottom of the window on the windowsill, and place the window tight against the wall. Make sure that all four nailing flanges are tight to the house. Have a helper position the window, from inside the home, so that the gaps around the window are equal. Level the window with a carpenter’s level.

Reseal the outside of the window using a self-adhering waterproof membrane, as you have done in step 3. Cover the entire nailing strip on the window.

Cut the j-channel for the bottom of the window, and add 2-inches. The extra 2-inches allow the j-channel to overlap one inch on each side of the window. Nail the j-channel with roofing nails. Cut the two side pieces, and the top piece of j-channel in the same manner.

Measure the pieces of siding, and use a pair of tin snips to trim the length if necessary. Lock one piece of siding onto the other piece of siding, and pull the siding up to make it tight. Nail the nails through the siding nail strip, leaving 1/16 to 1/8 of an inch of the nail head protruding from the flange. This will allow the siding to be able to expand and contract throughout the year.