Just A Bill,
Concerning you question of the footer gap not being seen from your photo there are 2 reasons.
1. At the end of a wall they would put a small blind to hide the exposed end of a wall panel to prevent revealing the footer on an end wall panel. Similar to when they wilded the console section next to Spock’s on the bridge they made a black cutout to hide the bare wood on the side of the console.
2. At the intersection in front of engineering or the transporter room they used large tubes ( 9 inches if my memory is correct ) to conceal the ends of the wall panels so they would not be seen by the camera.
Thanks, Robert. It's not really a concern, just an observation. The floor gap often does not exist inside rooms, so when an all-the-way-to-the-floor wall inside a room joins up with a gap-from-the-floor wall out in the corridor, there is naturally a step-up/step-down transition, most noticeable to me where doors slip into their pockets.
I first started paying more attention to it when I was scrutinizing a screencap of the sickbay doors leading into the exam room. The difference stood out to me more there because the walls are thicker on the inboard side of the main corridor, to accommodate the doors needing more room to slide behind inward-curving walls. (This can be seen on the set plans too.) I've misplaced that screencap, but here's a view in my rough 3D study model, laying on the floor in the main corridor and looking into the exam room in the general direction of where the surgical bed would be.
Anyway, I only mentioned it in the context of speculating about the height of the floor gap, which is a detail I must resolve for my scale model. Based on my plywood options, it makes sense for me to choose between 3mm and 5mm, which correspond roughly to 1" and 1.5" on the real set. Your reported gap measurement of 1.5" seems to agree with the DS9 crew's choices for T&T, since they show wall heights of both 10'0" and 10'1.5".
The obvious inference would be that the footer is a 2x4 lying on its side. I suspect this was the case for Desilu as well. The surviving 1960s elevation plan lists the walls at 10'0", and I believe those markings are all for
interior room walls. So it's hard to know whether the exterior (corridor) walls were that same height or were 1.5" taller. I suspect the latter, since they wouldn't have had a strong reason to go to the trouble of sawing an inch and half off of every corridor panel just to account for the footer gap, especially when the camera should never see the very top anyway. But of course this is speculation.
