Public Spaces and Backstage Spaces
While public spaces (e.g., corridors, entrance hall) are only temporarily occupied, they may deserve some acoustic treatment, especially as some of those areas may be designated as a waiting area for people with reduced mobility, and as such, some regulations  may require specific precautions. One will usually end up applying acoustic absorption on the ceiling so as to achieve an equivalent absorptive area of at least 25% of the floor area. Some extra absorption will be needed in such noisy areas as the bar area.
When the theatre facility is structurally linked to other buildings, especially dwellings, which is a situation not uncommon in Europe, a sore point will be the exits. They must be located as far as possible from the living spaces, bearing in mind that door slamming and eventual shouting are not the best of things at the end of an operating day when there are neighbors located close by! The trick usually is to apply acoustic absorption in the exit corridors and make sure that the doors do not slam violently. An even worse point will be the unloading and loading of the back scenes before and after the performance; while the former usually happens in daytime, the latter often is performed after the performance, that is, in nighttime. There may be shouts, the beeping of the truck backing up to the loading area, the noise from the forklift. The loading/unloading area will have to be properly located with regard to the neighborhood; this often results in an enclosed facility.
The technical area of a theatre can easily be sizable: There usually is one large AHU for the theatre, plus another one for the dressing rooms, one for the hall, one for the offices and cloakrooms, and smaller units for the sweet corner. While most of this equipment will stop after the operating hours, the cold room equipment will carry on. One must appropriately dimension the radiated sound power level of the equipment (including the relevant silencers and noise barriers).
Some facilities feature a small dwelling for the director. While this individual will be awake during the operational hours of his facility, his family might not be. More to the point, the living room often doubles up as a reception area for guests. Therefore, it is highly necessary to provide some serious sound insulation (at least 65 dB) with regard to the activities in the facility.