During the construction of the house, it was never assumed that the residents would once connect the balcony with the living room, thus increasing their living area. After all, as a rule, the area of apartments received in Soviet times was always too small. But to start work, you first need to calculate whether the base of the balcony will withstand. And agree on your actions with the authorities. So that in the room after unification with the balcony it is comfortable, the balcony should be insulated. Insulation requires the entire space of the balcony, not just the walls. There is a variety of thermal insulation materials with different characteristics of insulation. Mandatory use of sealants for sealing cracks and seams. In addition, there should be a warm floor on the balcony without fail. Otherwise, it will be possible to use additional area only in the summer.