It depends. Typically, you must seek the permission of your association when the improvement(s) involve or intersect common areas of the building or fall outside the unit/apartment boundaries as set forth in your master deed. Common areas of the association include main waste pipes, main electric service lines, main water lines, placing ducting or additional wires in the ceilings or in any ‘common’ walls between apartments or central hallways.
The association is most concerned that proper waste line size is maintained at all times and not overwhelmed by any additions within the building; That continued water service is provided at all times without interruption; That fire barriers between apartments and floors of the building is maintained at all times; The exterior aesthetics of the building are maintained at all times; That no holes, demolition or attachments are made to the exterior of the building to provide for continued safety of passersby; etc etc.
Further that your improvement(s) meet the association’s standards as set forth in the Governing Documents and avoids the problems that arise from the construction of improvements and the use of colors or styles that conflict with others in your neighborhood.