Laying ceramic tiles on vinyl

[jelly]

I live in a house that is about 40 years old and am thinking about laying ceramic tiles in the Kitchen.On preparation i removed our lino floor covering.Underneath were vinyl floor tiles stuck firmly to the original flooring which are again thin tiles but i am not sure what they are only that they crumble easily when i tryed to remove some in other parts of the house.
My question is instead of trying to take all these tiles up can i simply tile over the top with ceramic tiles.

 

[masona]

Sorry no,the floor adhesive need to soak into like plywood or floor screed as vinyl floor tiles will prevent that.

 

[jelly]

When i take these tiles up how level would the floor have to be.An extension to the kitchen was built.The builders screeded the floor and put leveling compound over the top.Although the floor doesn't seem that level to me +/-6mm in places.
where is the cutoff point where i can no longer use tiles adhesive to make up the difference in height.

 

[masona]

Although the floor doesn't seem that level to me +/-6mm in places.

You should get away with it but you could put more levelling compound if you want to.

 

[jelly]

Thanks Masona.
One last thing.when taking up these vinyl tiles the other tiles they are attached to come up with them.These tiles are very crumbly.They seem to be the original tiles.Anyway a concrete floor is exposed and in places black stuff is visible.I assume it is bituman.Anyway do i need to coat the floor with anything before i apply the tile adhesive.

 

[masona]

No as long as the bitumen are not loose,you can check this with a chipping hammer.

 

[jelly]

Sorry Masona i'm trying to get everything straight in my head before i comit myself.I had lino on my Kitchen floor.When i took it up there were plastic tiles that were stuck to the original fllor tiles.These original tiles were very crumbly.Someone suggested to me they could be lino tiles.I thought lino only came in rolls.Anyway what is the difference between Lino and Vinyl.
I am going to take your advice anyway and take all the tiles up as this will be a safer bet.But would it harm coating the floor with something all over or just in the exposed concrete areas and not the bituman.What would i use.

 

[masona]

Right,take up all lino/vinyl tiles so you can see the floor screed (sharp sand appearance) don't worry too much about the bitumen as it long it not loose,if so remove the loose bitumen then seal the floor with Unibond with part water.
You can tiles over vinyl tiles with Barrierflex but I don't agreed with it specially if there are some loose ex-tiles which will lift yor new floor tiles.See this for floor preparation.