Hydro advise for building terrace

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Hi, looking for advice on what type of hidro would be best to use for this. The owner installed on his own a makeshift drain a couple of years ago, and now it started to sip between the brick wall and exterior insulation of the building, and the other apartments below the terrace started to get mold and wall is damp. I want to dig out 1 square meter on each drain (more than in the video) and re-apply a hydro, and also block off the makeshift drains as they are not part of the building’s const...