Looking for Ideas

G'day, Kegasaurus.
Replacing the rotted timbers is pretty simple. The bottom wall to floor joint should have a horizontal timber on all walls. This ensures less movement so the waterproofing will not be damaged and fail. Just cut the bottom off each of the uprights so you can fit the new timber under each upright. The vertical timbers that have rot can be sistered down onto the new timbers at the wall to floor joint.

Relocating the floor wastes is going to be expensive and will result in a lot of work re levelling the floor to ensure proper drainage. I assume the level of the slab is about 15 to 20mm below the hallway floor excluding the levelling material?

Any idea how thick the levelling material is? The main concern with using a jackhammer is the job of filling/ levelling the surface ready for waterproofing. Also, keep in mind the shower base needs to close level with the bottom of the wall to floor joint on all sides.

Good luck and fair winds.

Originally Posted by kegasaurus

Haha, the floor drain isn't at the lowest point so some rectifying work is going to need to take place. The levelling material is all gone, the only bits left to get rid of are the built up areas where the bath and closet were. Both of these built up areas were done when the pour happened and are pretty solid. I was going to jackhammer these out, use a grinder to get out the lumps and then use a levelling compound to get the floor a little level before screeding. This will mean cutting, capping and filling the old masonry pipes. Yes, all new drains will be cored through the slab and finally, some traps installed so no more sewer smell.

The edge of the slab is only a cm lower than the floor, so I will take this down a bit as it's the highest part of the floor. I'm going to build up the hallway floors and hopefully, this will take a bit of the step into the bathroom away.

Hopefully, this sounds feasible.

The walls were indeed asbestos, but luckily I know a guy who is a licensed removalist and we both got rid of this. Came off pretty well for old brittle sheeting.

A question. As three side of the slab fall directly to the earth below, would aluminium strips be alright to use as formwork to keep the leveller in. I'm not very handy with the old jackhammer and there are a few chunks missing.

Common practice is to level the floor after sheeting the walls, no angles required.
The step down at the entry point will need to accommodate the depth of the tiles and the glue, you could grind out just this area and then grind a drainage path toward the floor waste. Any water under the tiles will flow through the tile glue as normal.