CHOOSING THE BEST THIN-SET FOR THE JOB
Thin-set is the cement-based go-to adhesive for most tile projects. As you’re perusing your options, you’ll notice a price range of $8 to $30 per 50-lb. bag. The least expensive thin-set is just Portland cement and graded sand, and it has worked for centuries. It’s appropriate for porous tile over concrete substrates.
However, most modern floor tile is porcelain. The more expensive “modified” thin-sets have various levels and types of polymer additives, which increases their adhesion and flexibility–as well as their price. They were developed to bond impervious tile, such as porcelain or glass, to most any substrate.
I use the best possible thin-set available for any given circumstance. Coverage for a 50-lb. bag is about 50 sq. ft., and a typical bathroom takes one bag. An extra 20 bucks to ensure that the tile will stay stuck is cheap insurance.