Timbeal: I believe the term "lofting" comes from when the sail makers would layout a full size pattern of the sail on the floor of the loft of their sail maker's shop. Then they'd cut the sail material to that size and sew it up to make the sail
When timber framers saw this method they adopted it to layout timber frames.
I think that's how it was created. But if I'm wrong I would believe that someone here will post the correct version of the story.