No it isn't advisable...both floors are floating floors and both will be moving (expanding/contracting differently)...could cause problems, when they start moving against each other.

Tiles dont float.

Also you may have to cut doors, architraves etc down, which then will be too short if you ever decide to change it again.

But it comes up easy...no stress, little mess :)

There is nothing wrong with putting one panel on another apart from the height. I wouldn't say this is not done properly but it will definitely be a problem with shaving doors etc as you guys said before. I had this once, that customer wanted me to lay 2 layers of panel flooring because he had 2 rooms done by someone before and the level was not right in other rooms. I have used 9mm ply in 2 other rooms. just think about the square meters I had to charge for!! :) not recommended by me personally.

Probably best to take old up first.If a jobs worth doing its worth doing properly

As a professional flooring installer, i say it is always best to go back to the subfloor. I.e. remove the existing floor covering and start again. As a few have said the height would be a factor, but the main thing is expansion....and can you be 100% sure the existing floor has been laid perfectly and is completely sound? Its not worth the risk of something going wrong.

You can but be aware that any doors you have might need to be cut smaller, because your raising the floor.

Its better and easier to take old floor up, shouldn't take long and you can dispose of it at your local tip.

hi,wood no as it can sweat and buckle , laminate yes as i have done this at least 10 times over the past few years and the only reason against this is the height difference/finishing issues with adjoining flooring [carpets especially] if you use a clic laminate and do have problems u can take up both floors and relay the new one, good luck lance

Yes you can but there's no point the floor is so easy to take up with no mess you would make moor mess going over it as you would need to shave all doors and loose your skirts

no laminate will expand and retract there will probably blow