TopFeatured.com

Previous owner had an unfinished addition on the house. The only entry into it is through a window (which I knocked out, and part of the brick and plaster) because the addition was on top of what used to be a porch + another addition. So this addition was framed and floored but basically built outside of the brick exterior.

Pics: https://m.imgur.com/a/lZHr5N1

Now that I’m in there I’m looking at the floor and it isn’t in great shape. It’s not flush with the walls and there are large holes that you can see down into my office in. So I have a few questions:

1. Should I just put underlayment + snap flooring on top of what already exists, and then put a ceiling in the room (office) below so you arent just looking up into it? I’ve done laminate before so this is familiar to me

2. Or, should I put down 3/4 flooring ply wood over top of the existing boards + laminate?

3. Or rip out the boards and just put the 3/4 flooring ply wood over the beams + laminate?

As you can probably tell I don’t know a ton about home improvement or diy but I’ve been doing what I can and trying to learn. I plan on just getting enough of an opening in the wall to get in and out as needed, do the floor, and then hire a professional to come do the ceiling, drywall, and door/entry into the addition proper. No HVAC so plan on doing a standalone heating /ac Mitsubishi wall unit.

Thanks in advance and sorry if this is against any sub rules.