There are many different types of adhesives out there that do and help with all sorts of things, so choosing a bag may not be that easy. At Home Tiles we sell two types of adhesives, our flexible, and our S1 Flexible, the main difference between the two is the S1 is deformable, allowing it to handle movement better like a strong washing machine spinning. Flexible tile adhesive is vital for any kind of underfloor heating, as the continuous heating and cooling will stress non-flexible adhesive and cause it to crack dislodging your tiles.