A termite barrier seal including a hollow seal body having a wall surrounding an axial bore extending from an insertion end to a surface end. A closure formation is located about the surface end for engagement with a closure for the orifice of the bore at the surface end of the seal body. A one-way valve at or intermediate the insertion end and the surface end of the seal body, the one-way valve arranged to permit liquid flow through the axial bore, but to prevent liquid flow to the surface end. An external seal about the seal body for sealing the wall of the seal body against the internal surface of a hole drilled through a concrete slab. An internal seal engages the seal body for sealing the wall against an external face of an injector when inserted into the bore of the seal body.
