We then had 12-14 inches of cellulose insulation installed on the attic floor. I placed a remote temperature and humidity sensor in the attic and compared readings between the inside and outside.

As an example, an R-30 rating is achieved by installing 12 inches of the loose-fill fiberglass material over the floor of the attic.

You can add insulation to the floor; the more the merrier. Just don't put it in the eaves. Also, make sure the attic is well ventilated. Cold roofs prevent ice dams.