We are in the midst of a house renovation where we are using part of the pre-existing foundation and abutting new foundation to increased the footprint of the house. Where the old and new foundation meet we have a small leak in the corner (approximately 2 feet up from the basement floor). It appears to be a slow leak but with a heavy rainfall we have seen a large puddle evolve. The contractor has applied the black waterproofing membrane twice to the exterior and hydraulic cement to the interior without success. It is now being suggested that we use a capillary system. If anyone has had experience with this system, is it effective for the long term? Anyone have other suggestions on how to handle this issue?