Italian to English Other Construction / Civil Engineering

Another doubt from my translation of a list of items in an expenditure estimate for contruction of a "foresteria". I'm sure this is embarassingly obvious for someone familiar with the sector, but I'm unsure about the exact meaning of the term "a filo" in the following phrase: "assistenze edili per posizionare gli impianti **a filo** delle strutture in cls". Thanks for any guidance, Sarah.