I had also found some sketches from the IIBEC that seemed to show a similar system with inverted t shapes:
IIBEC - Vintage Roof Systems
Thank you, I had come across the PSU site while looking more into this system, the Figure 10 & 11 photos look very similar to the second set of photos I...
I was hoping someone could help identify the below floor system. I cannot verify date of construction but was told sometime around 1900 in the northeast US. It looks somewhat like Dox Plank, but from what I can find, the construction date would be before when this system was generally used...