Un-even wall, +?-4mm? Plaster or adhesive?

[thompo]

Hello,

Planning on tiling my bathroom walls and have a query.
It was treated for damp, Plaster/render stripped, DPC injected and waterproofed sand cement render applied to the lower 1m of the wall.

We now have a mix of bare sand cement render that im told is the best to tile onto and the remainder of the room has old skim coat, very well adhered to the under lying render.

There is some minor variations in the sand cement, +/-2 or 3mm and then a bigger "step" to where the old skim is maybe 4mm.

Is this likely to cause issues or within tolerance?

Would it be worth smoothing the transitions with some tile adhesive or plaster before tiling? Other plan i had in mind was to use 10mm notch on the lower part then 6mm notch on the higher part to give the correct height?

Any value in use the wedge things to level the tiles?

Stripping the old skim off will take ages, ive tried and its well on there, easier to hack off the underlying render!

Cheers for any info.

Neil

 

[tpt]

What size tiles are you using?

 

[Skimmers]

as above

 

[thompo]

Sorry folks,

Honestly can't remember If they were ceramic or porcelain we had looked at.
Size wise they were 450x250mm or there abouts.

Will see if I can find out what they are tomorrow.

What is the worst case?

Thanks

 

[tpt]

well basically the bigger the tile, the harder the job will be because you can't work the tiles as much. A 4mm lip in the the middle of the wall will cause you some fun either way.

Building the adhesive out is possible, but even with a 10mm trowel the adhesive will squash down to around 4mm so you'll have to build out more than that