expanded foam

[geehippy]

I have just started my first paid job. I visited the customer prior to starting the job to measure up and set a price. The job was to tile a small bathroom all mats provided. The problem was that where the old bath had been removed and the new bath fitted, a lot of plaster had been lost at the foot of the bath. The customer said that they would sort this out . When i returned to start the job I found that he had used expanding foam filler to fill the holes, which were about 3 inches deep.
I have tiled over the foam but I am not in the slightest bit confident that they won't fall off as soon as the wind changes direction or some one looks at them funny.
Anybody got experiance of this?

 

[davy_G]

Have not tiles over expanding foam but how much of the tile had contact with the substraight? If it was 50% or over the should be OK with a good adhesive and a good twist of the tile.