Should the flashing at the base of the wall be positioned higher if thick vegetation will be located around the wall base? If so, should the flashing be located above the vegetation or the expected height of the vegetation?
Typically, I would not position flashing above the expected height of the vegetation. Even when thick vegetation is present, water can flow out of the weepholes and travel down to ground level. In addition, the height of the vegetation typically is not known and will change over time. If the vegetation is eliminated in the future, then the flashing will have been placed at too high a level, exposing unflashed masonry below. I recommend positioning through-wall flashing a few inches above the expected grade. It is important that weepholes not be covered by soil and that the flashing be sealed to the foundation wall below.