How flat do walls need to be for tiling?

[STEVEROG]

How 'flat' do the walls of a typical shower enclosure need to be for tiling? I have an enclosure that will need tiling in a month or so and want to get the preparation right. One wall is aquapanel on studwork and is pancake flat. However, the other two walls of the shower enclosure are plaster over render over brick. I am not sure how much variation on these yet. I will get a long level on them tonight and see.

Steve

 

[grumpygrouter]

Flatter the better!

 

[STEVEROG]

Is there any 'rule of thumb' as per how much variation over a particular distance, say over a tile width?

I think the walls will probably be pretty 'flat' from this point of view and probably over a metre or so. However, I doubt they are in plumb. Is this a big issue?

 

[grumpygrouter]

usually max +/- 3mm under a 2m straight edge

 

[STEVEROG]

OK,

Thanks for that.