Could I damage the foundation pulling up old floor boards in this old house?

Q: I have pinewood flooring in a 100-year-old house–2.5 wide boards, not planks. There is no subfloor, with the boards sitting right on joists. I want to install a new hardwood floor, and thus a subfloor.

I’ve been told that it wouldn’t be safe to just pull up the old floor boards, as on a house this old they might be providing structural rigidity and I could damage the foundation. Is that true?

A: I’m not an engineer but I’ve not heard that one before. Still you have multiple options open to you. You could perhaps install directly onto that pine floor or you could screw 3/8 plywood over it into the joists and then the hardwood on top of that. Or if there are height issues and that is why you wish to remove the pine, you could take it up in sections and install 3/4 spruce plywood as you go.