I have a two story stucco house and between the first floor ceiling and second floor floor there looks like an existing sheet metal horizontal exterior flashing (embedded in the stucco but jets out about 1/4 inch)across the stucco wall. The vertical stucco wall is flat. When I install the new flashing for the patio cover do I flash in above or below the existing flashing? Is there a web site showing what kind of flashing to use and installation methods? Thanks.