A window drip cap will keep water from leaking in behind the trim and into your walls. The drip cap is installed to the top of the window and diverts water away. Installing a window drip cap is an easy project and can be done in less than an hour.
Measure the width of your window and buy the correct size from the home center. You can purchase an already formed plastic or aluminum drip cap.
Dry up the section of siding that is just above the window. If you see any type of wood rot there from previous leaks, then now is the time to replace the wood.
Install Drip Cap
Cut the drip cap to a length just wider than the window. Apply some flashing tape to the window and exposed sheathing area. Slip the window drip cap under the siding and nail to the sheathing with galvanized nails. Make sure the cap slopes away from the window so the water will fall away instead of running back towards the house.
Apply some caulking to the top edge of the drip cap and cover nail heads with also. Cut the overhanging parts of the drip cap and fold them in towards the window. Reinstall the siding and caulk both ends of the drip cap.