I have a 1600 sq ft attic with no insulation in the cavities. The tongue and groove flooring runs the entire length, the fastners have been in place since 1925. Is there any short cut where I won't have to pull up all this flooring?
Unfortunately, no. You could drill holes in the flooring and use blown in insulation. Or, you could leave the flooring in place and lay the batts of insulation on top of the floor. Just carve out a space to use for storage and place the insulation on top of the rest.
Keep in mind that most attics need 19"- 22" of insulation. So, even if you removed the flooring and filled in that space, you'd really need to add more on top of the floor to bring it up to that level. Finally, make sure that you add additional attic ventilation too, so that the new insulation stays dry.