Near Death Again!

My father called me and asked if I was willing to build a second story in the Fitchburg Plumbing warehouse that was newly constructed. He had plans and had purchased a predrilled girder system that would be about 15 feet above the cement first floor. I had a small crew of helpers and we had to clear all of the warehouse items from below where we were putting up the steel girders. We had a lift to help us because the I-Beam girders and the flooring (1 1/4 tongue and grove 4'x8' plywood sheets) were very heavy. I was working in an area where we were putting in metal flooring that allowed light to go through to the first floor. I stepped on a piece of the flooring that was not tied down and I was soon in the air heading for the cement floor 15 feet down. I grabbed for the girders but could not hold on. I was falling with my body out prone so when I would land I would be hitting the cement floor with my head and body at the same time. A quick thought crossed my mind - will I survive? Someone was looking out for me that day because I hit a cardboard box that was about 3 feet high. Inside the box was a coal burning furnace so the landing still hurt but was not deadly. It was the only warehouse item we had not moved. I went up to the 2nd floor and started to work again and I hit another loose flooring but did not fall. I had the workers bolt all of the loose flooring. Next day I awoke with black and blue bruises up and down my legs and arms.