thick bed or ply on concrete ? help

[bmx]

i have a hallway to tile i have 55 400x400 porcelain tiles all cut to size, but i have two probs the concrete floor has a bitumen layer of paint on it, and to get the level to meet up with the other rooms i would have a 10mm to 12mm bed of adheasive. i could also do with it setting as soon as possible as its the entrance to the house, oh and its -4 deg outside will that matter?

so my questions are, what should i do?

spend hours chizzle away the bitumen then use what for a thick bed adhesive that will set quick?

5mm ply or some kind of board screwed to the concrete then use what adhesive ?

 

[Richard C]

Tiling on to bitumen can be problematic. A typical solid bed cement based adhesive bed is 4-6mm, it can be used up to around 12mm locally but you can’t tile over the whole floor in 10-12mm thickness; it will cost you a fortune, you will never get the tiles level & it will look pants. You can’t tile at -4 deg either, you need a minimum temp or +5 to lay the tiles. A decent Rapidset can be grouted within 3 hours at normal temperature but longer if colder & it will still hold water so if it freezes overnight, you will be in trouble & it may well fail.

For leveling the floor, look at using a self leveling compound but make sure you pick one that will cope with the thickness you require; some will do up to 50mm but many are only good for 3-7mm, or use a decent tile backer board. I would not advise ply, even WBP is not dimensionally stable if exposed to damp & if there is any hint of dampness in the floor, it could curl & there go your tiles. Only use quality trade cement powder adhesive (Rapidset) & use a flexible addy & grout over the SLC or backer boards.