Remodeling around cast iron toilet flange

Hi folks -

I'm on a project where the homeowner had a tiled bathroom floor that "crunched". The floor was over a 6" high dirt crawl space. I ended up taking out everything down to the floor joists. The extent of the demolition is in the pic below.

During the demo phase, I removed 4 hex-head "screws" from the toilet flange, thinking they anchored the flange to the subfloor. Turns out they were bolts and washers, not screws, and they weren't anchoring the flange at all. Are they for a compression-type cast iron flange? If so, can I just re-tighten the bolts, or did I compromise the flange by removing them?

Also - I don't see any holes in the flange for screwing it to the subfloor. Is this possible or am I just not seeing them? Do cast iron flanges need to be screwed down or are they solid enough that they stand on their own?

Thanks

A cast-iron flange that is set into a cast-iron pipe with lead and oakum will normally be fine without being attached to the subfloor. Any flange should be install on top of the finished floor, not directly to the subfloor. I would get a new flange and install it properly.

From your description, it appears that you have a compression flange. Whether it is reusable or not is something we cannot decide without actually seeing it. Whether a cast iron flange needs anchoring or not depends on how the closet bend is attached to the piping, but a compression flange might not be sturdy enough without screw anchors.