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!
Here's what I've done in the past and will keep doing in the future. Since we're already rebuilding everything anyway might as well just redo the entire floor.
Are PVC pipes like that common for water lines in the UK? In the US they're illegal in some parts of the country and are typically seen as "not if but when" they'll fail. I've seen them just randomly explode and dump full pressure water into somewhere.
Might be slightly different in the UK but the way they're installed in the US is gluing the different CPVC pieces together. This is different than PEX which is the more modern method and is crimped water lines.
In the UK most/all kitchen and bathroom waste pipes are the white plastic. They have solvent weld and push fit options. 32 + 48 mm options (I think) Pressurised mains water is in copper or pex. The only law I remember is that you can’t put pex directly to your combi boiler - you have to have 6ft (?) of copper before any plastic push fit.