Katarina Udički building, completed in 1927., was designed in 20th century Academic style by Đ.S. Jovanović. Street-facing facade is characterized by extensive decoration of balconies and cannulated cornice pilasters. The building is under protection of Belgrade City Institute for the Protection of Cultural Monuments as being a part of „The Old Belgrade“ quarter. The design brief called for a construction of a roof extension atop the existing second floor and creation of a duplex living unit. The extension follows the roof height of neighboring objects and volumetrically completes the street front. The new terrace, setback by 60 cm from the cornice edge, is introduced and fenced by a masonry wall in order to sustain materiality and decoration language of the current facade. Designed steel frame with translucent facade envelopes two added levels and emphasizes the symmetry of the old building while creating a contrast with preexisting monumental opaque facade elements.