A masonry unit may include a main portion having end surfaces, a primary side surface, and a secondary side surface, and an auxiliary portion positioned adjacent to the main portion and defining an auxiliary void. The auxiliary portion may be connected to the main portion at the secondary side surface. The auxiliary portion may include an auxiliary wall being spaced from the secondary side surface to define the auxiliary void therebetween, and at least one bridging web extending across the auxiliary void and connecting the auxiliary wall to the main portion, the at least one bridging web being inset from the opposite ends of the unit, the at least one bridging web being integrally formed with the main portion and the auxiliary wall. The auxiliary void may extend from one end to another end of the unit and may extend from the top to the bottom of the unit.