Z-bar flashing, why it’s used and what it’s for.. .. A lot of projects I’ve seen siding installed without flashing, or improperly installed flashing. The best was a whole house with the z-bar backwards, basically creating a water trap behind the siding. How stoked would you be? .. This scenario would have a piece of siding above, but I wanted to show the bar and tape in action. Z-bar acts as a guide for any water, allowing it to come out over the siding onto the face. The little effort and mater