In the 18th century, the proliferation of liturgical vestments required veritable wardrobes. The medieval sacristy, where sacred vases, books and relics were also kept, had become too small, so Abbot Jacques Hache decided to enlarge it and install it throughout the ground floor of this brick building. On the upper floors, 26 monastic rooms were added to those in the monks’ dormitory.  The north wall of the sacristy was equipped with wall cabinets on either side of the door to the church.