Tiling over old tile cement and screed floor


Old 09-14-08, 03:24 AM
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Tiling over old tile cement and screed floor

Hi Guys

Great Site by the way.
Area - Joint Kitchen and Lounge in a unit ( 42 SQ Meters).
Floor - Solid concrete all round.
Lounge - Removed carpet - screed underneath and straight.
Kitchen - Removed old ceramic tiles.
My problem: After removing the kitchen tiles I have the old tile cement left underneath, it is very thin +/- 1 -2 mm only and EXTREMELY hard to chip off. Am I able to Tile over this and if so what preperation would I need to do?
I think I can compensate for the difference in hight that joins my lounge area as it is not very much.

2nd Question: Do I need to prep the screed(lounge) floor by chipping it or treating it before I start laying the tiles.

The tile I am using is 400X400mm ceramic with a 5mm gap.
I would also like to say that I am on a budget otherwise I would have rented this machine with a spinning diamond head foor $300.00 per day to remove the old tile cement, but I do not want to do this if it is not required.

Thank You very much
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Old 09-14-08, 06:32 AM
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Hi Kevin!

I always recommend getting as much of the old thinset off as you can, but 1-2mm is fairly minor. You just want to make sure there are no high spots that would make the tile "rock".

They do have angle grinders with a diamond removal pad that could help remove some of this, but it is really up to you.

How does the screed look? Are there any cracks?

If no cracks, you just have to make sure the floor is clean and free of dust and debris, then tile with a good modified/fortified thinset.
Old 09-14-08, 07:12 AM
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Australia heh. All this metric stuff makes my head hurt.

The key here is to make sure that the remaining mortar is well bonded to the slab, and you dont have any high spots and low spots. You want to start with a flat surface, or things can get out of hand quickly. You can fill in low spots with a portland cement based patching compound, and grind down any high spots that tiles might rock on.
Old 09-14-08, 05:28 PM
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Hey Guys
Thanks a million for the advise - Man, am I relieved that I do not have to try and remove the "thinset" off the kitchen floor - It is very solid and stuck on to the kitchen floor.

The screed does have two cracks through the floor - Am I able to just use the tile cement to file in these two cracks or should I get a normal concrete premix?

The thinset on the kitchen floor has "air pockets" - Am I also able to use my tile cement to fill this in?

I do not think I have any high points anywhere as the previous tiles that came off were pretty stuck on there.

I was also told to "chip" my screed so that the tile cement will bond better to the floor - Is this true?

Many Thanks so far for all the help - I'm sure I'll have more questions as I go.
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