Tile On Tile - Scratch Coat Question

[tafkap68]

Tiling a floor next week, customer wants me to tile over existing unglazed tiles. I will be putting on a scratch coat first so I have a couple of questions...

What is the recommended layer of depth for a scratch coat?
Which type/quality of sand is best suited for the job?
What ratio of sand to adhesive should I mix?
Getting adhesives from Topps, do they sell sand?
How much sand will I need for 38 sq M?

Cheers!

 

[DHTiling]

Any reason for wanting to apply a scratch coat.....if floor is out a bit then surely a latex leveller would be better.. very little increase in floor height and faster set time than scratch coating....seems alot of expense to go too......

1 : clean tiles..

2 : apply metal lath sheets...or similar..

3 : apply scratch coat.....10mm to 25mm

4: leave 48 hrs to tile....

Will easier to self level and tile next day....hope this helps...........dave...