My house was built in the 20's and everything sags. The previous owners answer was to have the doors to all the rooms on the second floor cut to fit the shift in the door frames. My issue is my kitchen floor. It sages drasticly. It is about 15'x15' and sinks about an inch in the middle. I have total access in the basement. The beam span in the basement is 16 feet. I want to put a parkay floor in the kitchen and am sure the pieces will not quite fit with this sag. Can I raise the sag by putting a beam in the basement. If so, how do I go about this.