Slightly bowed floor - options

[Tommcd]

I'm about to embark on tiling my bathroom floor. It's a new build. So far have whacked down a load of hardiebacker and was about to start tiling - however, I assumed (stupid I know) the floor would be flat, with it being a brand new house, but it actually bows quite a bit. It dips about 6-7mm in the centre over a distance of 1.9m.

Just wondering what is the best course of action...

1) SLC the dip - if I do this, will the hardiebacker and adhesive already down be a suitably watertight bed for the SLC?
2) level the dip with rapid set addy
3) tile it and make up the void with extra addy as I go
4) tile it as is and convince everyone it's actually flat but some weird optical illusion is going on.

Sorry for the long post -Merry Christmas!

 

[macten]

If it's only a smallish area I would pile on some rapid set and float it in with a straight edge, larger area I would SLC. Only you know if there are any gaps that the SLC could get into, if there is then fill them first and prime the board.

Here's one I did earlier in the year, to be fair it really needed a new floor but I got called in too late for that to be an option.

 

[On one]

If you're going to go down the route of pouring SLC, just gap fill any voids with tile adhesive and run some silicone around any radiator pipes

 

[Tile seller]

I'd slc the worst of it. Probably be worth it for the cost of a couple of bags.

 

[hmtiling]

expanding foam for gaps and slc

 

[Tommcd]

Cheers folks, I'll probably stick some rapid set on it, just because I can bridge the gap easily with a straight edge and it'll allow me to tile a few hours later. Basically I can't be bothered to go to the shops tomorrow and I've got tons of rapid set at home...