I'm currently working on renovating the bathroom in our 1958 home. I just finished tearing out the shoddy job some flippers did a few years back, and found some issues with the floor that have got me scratching my head. I've learned that it was common practice back in the 50's to have a mortar slab subfloor, and it looks like that's what I have in our bathroom (except where the old bathtub was, where there was just 2 layers of 5/8" plywood). The tile was adhered directly to the slab with no decoupling membrane, and the only way I could get it and the thinset off was with a rotary hammer. I'm afraid that might have been too aggressive though, because now there's a bunch of cracks in the subfloor. I'm not certain if the cracks go all the way through because the bottom/sides of the slab are hidden. But I'm also not certain the actual original mortar slab is cracked, or if the flippers put a super thick layer or two of leveling compound down, and that's what's cracked, because in one area where I accidentally made a deeper gouge, it looks like there's about an inch of smooth grey mortar-like substance at the surface, but beneath that is a lighter-colored concrete-like substance with an aggregate mixed into it.
I'd like to get some more opinions on what's actually going on here, and what my next steps should be. Can I put leveling compound down as-is, do I need to patch/fill the cracks, do I need to fully chip away this smooth, grey top layer, or do I need to tear out the slab completely and lay a new plywood subfloor?
Imgur link for reference: https://imgur.com/a/xF7go4z
I can add more photos if needed. Thanks in advance!
So you already have down to the studs, if you have any kids this is what you had them for. Send them in with masks and sledge hammers to break the rest of it up and burry it in the back yard woods/brush/where you need fill but dont care about clean topsoil fill (assuming this is rural).
Obviously take this with a grain of salt because im not looking at it in person, but I cant see very much water damage to be concerned with from the pictures. Even if there are spots that are structurally comprimised from water damage, just cut the sood out and sister in new supports. Once you have the concrete out youll have a look at the sub floor. Thats guna have the most damage if there is any and will likely get replaced because why not you are this far in amd all it is, is some plywood. If any of the joists or studs are water damaged, just sister new pieces of wood. Once the remodel is done and done correctly, you will have zero reason to worry about further water damage or water damage spreading.
Its unlikely the floor has been cracked like that for long. Again if it were like that for a long time, you would feel floor joists bouncing, wood flaking away, and black mold errywherrr. Even if you dont see any mold, after you finish demo but before you do any work, spray everything down with a mix of bleach and water.
Use all the recommended materials. Pinching a penny on the wall materials or flooring will absolutely cost you a whole other renovation before you sell. Calk everything. Then caulk it again and keep on caulking every sign of wear.
All in all id say for how old the framing looks, its not in bad shape for its age. For a second opinion, other than yours and random internet peeps, just call local contractors/tile guys for a quote. Tell them you are broke as fuck. That way they dont come in trying to upsell you on stuff and will give you the bare essential needs which will give you a better idea of what does need to be replaced and what is good to remodel over.