[Closed] Best way to level 15mm fall in floor?

If I wanted a consistent stable floor I'd be ripping up the floorboards leveling the joists and continuing the chipboard across.

I'd build up as much as possible 1st by over laying strips of tile backer board* to get a rough level, then use 2 part latex level compound over the lot to finish of the process. trying to pour to 15mm in one hit will cost quite a bit of cash. *this is assuming what's there is screwed down and stable.

Don't buy that crap levelling stuff from B&Q, get some proper 2 part latex based ie. Ardex NA or similar, at a push Screwfix do a Mapei one bag that's ok.

make sure you've dammed up any gaps or cracks as the compound will find them!

What joshvegas says, it can't be a big job, in a shower room.

make sure you’ve dammed up any gaps or cracks as the compound will find them!

This, and this some more. When you’ve tipped the six thousandth gallon and the area still isn’t full, don’t keep going. When I used to do site works, the amount of time we had work trashed because some idiot kept pouring and pouring and pouring the stuff, never once questioning why he’d mixed enough to level the Cairngorms yet this small section of flooring is still needing a touch more.

Great stuff used correctly, but make sure and existing flooring is solid.

I'm thinking Blazin has it.

The width of floor the fall is over is only 1.2m. I can double up the 10mm board at the furthest end and then buy a 6mm board and create two steps. Then use minimal levelling compound to smooth the steps.

Seems the easiest, quicker and cheapest option from this point.

Thanks all

15mm in 1200mm is quite a lot and would be quite noticeable when walking on it.

Are the floorboards aligned along the fall or across it? And do they extend outside the area you are levelling up?

If the floorboards are across the fall then that means that the joists being at right angles to the boards are in line with the fall so I'd go with the "remove the floorboards, pack the joists and lay chipboard across the whole lot" method (I'm assuming that the fall is in one direction only). If everything is 90deg to the above then I'd go with the "packing with board on top of the floorboards then using levelling compound" method.

Also depends what's under the floorboards, if there's pipework or wiring I wouldn't cover with levelling compound.

Also depends what’s under the floorboards, if there’s pipework or wiring I wouldn’t cover with levelling compound.

Doesn’t really matter if it’s having tile backer board and tiles over the top, any leaks and the easiest access is through the ceiling downstairs!

Has the floor just settled over time? or is it rotten?

We're in a 115yr old house, joists look ok.

Floorboards run in line with fall. So I'll create steps with backerboard and then smooth the transitions.

yeah best way, as blazin says. i've used tilemaster self levelling for years and seems good stuff, they deo one that does upto 50mm in one go and also a rapid one which flows really well but you do have to work quick, its very rapid if its warm.
foam gun is good for making sure all the holes are blocked up or making barriers to stop it going where you don't want like under kitchen units or baths or out of the doorway.

If I wanted a consistent stable floor I’d be ripping up the floorboards leveling the joists and continuing the chipboard across.

Ditto.

Another +1 for lifting the floor an relaying it level. You can also have a look at the joists and work out what is going on. Leveling compound won't help if it drops another 15mm over time.

if the floor has dropped that much is it still moving a bit? that would be my concern thus cracking when tiled?

floors in my flat are all over the place - one room has a 4" drop across it. its not going to fall down but it does move around with changes in temperature and humidity leading to some cracking in plastered stud walls.