I need to access some plumbing above the porch for my 2nd floor bathtub and there is this approx. 3" width wood paneling.
What is the proper way to uncover the underside of this floor? I don't see any set nail marks, and the paneling is butted against that metal skirt.
That is a blind-nailed tongue-and-groove ceiling.
It was installed by nailing the first board to the ceiling joists through the tongue, so that when the groove of the next board was placed over it, it would cover the nails for the first board, and you then nail through the tongues of the next board, and so on.
The last board wouldn't have it's nails covered by any succeeding boards, so that board at one end or the other of the ceiling would have nails showing. That's how you identify where to start pulling boards off.
To remove boards from the ceiling, you start with that last board you identified by carefully prying it off which will reveal the nails on the next board. Then then repeat until you get to the bathtub that you need to inspect/repair. You'll find plenty of videos online about removing tongue-and-groove flooring if you want more details.
Yes, I just described a very long process that will take a long time, especially if the tub is at the opposite end of where you need to start.
An alternative is to sacrifice a board in the middle that you will likely split while trying to get it off. That could reduce the number of boards you need to pull off, but you may be left with a splintered board that may or may not be able to be glued or otherwise returned to a serviceable state. And it looks like that ceiling is weathered enough such that a new replacement board (If you can find or make one to match) would have a different visual appearance that may or may not be acceptable to you.
Another alternative is to rip a board in the middle lengthwise at a 45 degree bevel right along the edge of the tongue of the board where you want to start. This would cut out most of that board while leaving behind the tongue with it's nails in it. I've done this on interior tongue-and-groove subfloors with good results, but that is using a circular saw in the normal orientation. You would be holding a circular saw upside down while standing on a ladder, so a far more precarious of a process. (And in addition you probably won't be able to get the entire length cut since you can't get all the way to each end with a circular saw.) But this would leave you with a relatively intact board that could be face nailed back into place and be less noticeable than a splintered or new replacement board.
