The Singer Building was intended to be fireproof, and the tower section used mostly concrete floors, with wood used in some doors, windows, railings and decorative elements. The base used more wood than the tower, mainly in the floors, windows, and doors. All the building's stairs were made of cast iron. The interior trim in the Singer Building was made of metal painted to resemble wood, including in the doors. Actual wooden furniture was used in the Singer Company's main offices on the 34th floor. There were also ornamental plaster features executed by H. W. Miller Inc. Plaster was used extensively for the walls and ceilings. The usable office space in the building totaled .
