Absolute Disaster

Please give me as much advice as possible--I've created a huge, expensive mess--and a hazard as well!

I've tiled over several plywood floors in my new home with few problems. So, I decided to buy bullnoze tiles for my stairs and spent many hours tiling the wooden stair treads using versabond fortified thinset mortar and terre cotta tiles.

They don't stick. As I walk on them, even after letting them dry for days, they come right off--please advise! What did I do wrong and what mortar should I use?

The only thing i can think of that has happened is that wooden stairs have a fair amount of give in them so when you are walking on them its loosening the tiles because of this. Have you tried Bal flexible floor tile adhesive?

I have not tried a flexible adhesive--what are the pros and cons of using a flexible adhesive rather than a cement backer board and remortaring?

With the flexible Bal stuff it sets almost like a dense rubber and is suitable for laying on wooden floors. I see from your post that you are in the States , but you must have something available with flexibility over there. I would suggest using this or similar. Have a look at Bal-adhesives.co.uk and the adhesive is called Bal Fastflex. Good luck.