A brush seal includes a bristle pack disposed between a top plate and a back plate. A sliding backing plate is disposed between the bristle pack and the back plate. The bristle pack includes a first bristle set that extends across a seal gap between a first engine component and a second engine component to prevent leakage across the seal gap and a second bristle set that exerts a force on the sliding backing plate. The sliding backing plate supports at least a portion of the first bristles and extends across the seal cavity to contact the second component. The force exerted on the sliding backing plate drives the sliding backing plate into contact with the second component.