Installing window flashing is a necessary part of installing a window. Flashing keeps water from entering the cracks in the window and causing water damage. It is usually made from galvanized steel or aluminum and should be installed before you put the siding on your house.
Step 1: Use a caulking gun to run a thin bead of silicone sealant around a window frame.
Step 2: Cut out the flashing so that it will overhang about 1/2 inch from the window on both sides.
Step 3: Stick the flashing around the window and nail it in place using the pre-made nail holes.
Replacing Window Flashing
If your house is old or someone didn't install it properly, you may have to replace your old window flashing with new ones. The process is pretty much the same except that you will have to work behind the siding that is already in place. You will also have to remove all of the old debris from the area before you can apply the new materials. If you don't feel comfortable installing your own flashing you can hire a professional to do it for you. It is much better to have it done right the first time than to have to go back and fix it.