Metal cap flashing/drip edge on windows and doors – still recommended with modern tapes and liquid flashing?

A builder working on a home in Southern California asked a construction forum whether metal drip caps above windows and doors are still needed now that modern sealing tapes and liquid-applied flashing (a brush- or roll-on waterproof coating) are so good. The project uses flanged windows and doors sealed with tape and liquid flashing, plus a rainscreen wall assembly, which is a design that leaves a small air gap behind the siding for drainage and drying.

One expert who replied pointed out that metal head flashing has always been more of a regional habit than a universal rule. In wet coastal climates it is often required by code, while builders in drier regions often skip it. His view: if a wall is likely to see enough water that it needs a way to shed it at the top of a window or door, a metal drip cap is worth having, especially on a rainscreen wall. He noted a wrinkle many homeowners would not expect: rainscreen gaps can actually let water sneak sideways into the wall cavity at the window head if the flashing has no end dams, small returns that block water from creeping around the sides.

For homeowners, this is less about a decision you would make yourself and more useful as background if you are having windows or doors replaced or added. It is a reminder that the choice of window flashing details depends heavily on your climate and wall design, not just on how modern the tape or sealant is.