Bill from Paradise, Newfoundland writes: "I need to settle a bet between a buddy and myself. When you put in a vinyl window should a drip cap always be used? My buddy never uses one, and claims water never gets in under the window." Well Bill, you win. Yes you should always put a flashing over the top of a window, called a Drip Cap. If you rely on caulking to prevent water from coming into this joint, it will eventually leak, sooner if the window sticks slight out beyond the siding as it usually does. Why? Because water will sit on that ledge and degrade the caulking. Critical joints like this one t...