A device for post-installation in-situ barrier creation, comprising a multi-layer fluid delivery device and at least one injection conduit member (20, 20A, 20B, 20C), wherein: the multi-layer fluid delivery device comprises first and second layers defining an intermediate open-matrix layer for an injection fluid; the first layer has an inwardly facing surface and an outwardly facing surface, the first layer being permeable to the injection fluid but at least nearly impermeable to a structural construction material to be applied against the outwardly facing surface of the first layer, and the second layer is water-impermeable and has an inwardly facing first side and an outwardly facing second side, the inwardly facing first side of the second layer being affixed, directly or indirectly to the inwardly facing surface of the first layer such that all or a substantial portion of the second layer is spaced apart from the first layer, using an open-matrix structure to create air space between the first layer and the second layer and thereby defining the open-matrix layer for conducting the injection fluid between said first and second layers; the at least one injection conduit member is disposed in parallel orientation with respect to the first layer and second layer, the at least one injection conduit member being for conveying the injection fluid into the open-matrix layer air space; the at least one injection conduit member is: (i) located within the open-matrix layer and thus between the first and second layer, (ii) located adjacent the open-matrix layer; (iii) located against the outwardly facing surface of the first layer which is permeable to injection fluid; or (iv) located in a combination or all of the foregoing locations (i), (ii), and (iii); said device for post-installation in-situ barrier creation being characterized in that the at least one injection conduit member comprises polymer tubing having openings which are resiliently movable from a closed to open position when the conduit member is filled with the injection fluid under positive pressure. the multi-layer fluid delivery device comprises first and second layers defining an intermediate open-matrix layer for an injection fluid; the first layer has an inwardly facing surface and an outwardly facing surface, the first layer being permeable to the injection fluid but at least nearly impermeable to a structural construction material to be applied against the outwardly facing surface of the first layer, and the second layer is water-impermeable and has an inwardly facing first side and an outwardly facing second side, the inwardly facing first side of the second layer being affixed, directly or indirectly to the inwardly facing surface of the first layer such that all or a substantial portion of the second layer is spaced apart from the first layer, using an open-matrix structure to create air space between the first layer and the second layer and thereby defining the open-matrix layer for conducting the injection fluid between said first and second layers; the at least one injection conduit member is disposed in parallel orientation with respect to the first layer and second layer, the at least one injection conduit member being for conveying the injection fluid into the open-matrix layer air space; the at least one injection conduit member is: (i) located within the open-matrix layer and thus between the first and second layer, (ii) located adjacent the open-matrix layer; (iii) located against the outwardly facing surface of the first layer which is permeable to injection fluid; or (iv) located in a combination or all of the foregoing locations (i), (ii), and (iii); said device for post-installation in-situ barrier creation being characterized in that the at least one injection conduit member comprises polymer tubing having openings which are resiliently movable from a closed to open position when the conduit member is filled with the injection fluid under positive pressure.