correct way to tackle uneven floors

[marcus]

Time and again when tiling floors either timber (ply) floors or old concrete floors I struggle to work out the best way to correctly approach uneven floors.
If for instance when looking at a concrete floor (recent example) of 22sqm with an area of particulary high point compared to the rest of the floor, do I try to level all the floor to this point (varying from 5mm to 40mm over the whole floor) or use this high point keeping it tight to here and bed it out with adhesive? Either way there is going to be an enormous cost and possibly incorrect use of adhesive to level the floor or multiple layers of self levelling compound.
The high point in question on this job is so large it is impossible to break it away to a lower level.
I am tiling large 400 x 900 limestone tiles in brick bond and obviously everything has to be spot on to avoid lippage.
I would really appreciate any advice from the experienced tilers out there.

Many thanks,

Marcus

[Dave]

You could of course try and grind the very high spots off before using a suitable SLC..

[doug boardley]

You could of course try and grind the very high spots off before using a suitable SLC..

that's what I'd aim to do

[peckers]

if im reading this right are you saying the highest point is 40mm higher then the rest of the floor?

[SandyFloor]

I have a system for screeding extemely uneven floors. I don't know what everyone else does but here we go.

First I use a laser level and place plywood packs ( about 40mm sq.) of varying thickness every 1500 mm over the floor area so the top of the packs are my finished level. I then prime the floor.

Secondly I use a slc I can use with an aggregate with to fill the more extreme areas using a spirit level resting on the packs to determine the depth my screed needs to go to. I will stop this one about 3 or 4mm short of the top of the packs and leave to set. The aggregate makes your slc go a lot further.

Thirdly I will spread a slc (after priming again) without aggregate until level with the packs once again using a spirit level. If the packs are slghtly proud It's easy to knock off the tops with a chisel.

I've done this a few times on farmhouses where the floor can be up and down a yo-yo and it always ended up dead flat.

[marcus]

hi peckers

yes the highest point is 40mm higher but the rest of the floor is basically all over the place below this level

[Alan.P]

Same sort of thing as Sandy, use packers to height required as a guide for the slc.

[peckers]

Similiar to the other guys but I find my finish floor height needed before tiling then i screw down to the floor door stop using window frame packers to level it up about 3mm below finished level, i set these out in bays and then fill the bays with an slc with aggregate to bulk it up and i use the doorstop as bearers to rule it off too. once dry enough i then remove the bearers and then fill in where they were, and then finish off with a normal slc
Basically the same as the other guys but each one finds what suits them best.

Ardex do a slc with aggregate already in called ardex k15-hb this is great to use or you can bulk it up even more if you need too.

[Glasnevintiling]

can any1 post pics of doing this pleas as i'm interested to know how to level floors perfect,was going to do a course in the UK ableskills any1 heard of them ?