I would like to use an offset brick to create a reveal in a masonry wall. The back side of the offset brick will project into the masonry cavity. The Brick Institute of America recommends a minimum 2-inch-wide cavity. Should the cavity width be measured from the back side of the offset brick, or should the offset brick be ignored when determining the cavity width?
Using full-size brick to create reveals in a masonry drainage wall can cause major disruption within the masonry drainage cavity. Not only do they occupy some of the space of the 2-inch cavity, but they form a ledge for mortar droppings to collect. Their presence also makes it virtually impossible to use a drag board in cleaning the masonry wall of mortar droppings. For these reasons, I recommend using a brick that is reduced in width at the offset. Structurally, the back portion of the offset brick serves no function. Cutting the brick to a narrower dimension or having special brick made can eliminate the problems described above. An alternative would be to maintain a 2-inch cavity from the back side of the offset brick to the back of the wall.