The introduction of Schluter-DITRA “universal underlayment for ceramic and stone tile” has raised a lot of questions:

• What exactly is the purpose of floor-mount backer board?
• How does the new product compare?

Additionally, there was already a wide variation in what was considered acceptable backer material and thickness.

Therefore, I propose to tackle the following subjects:

• What was the structural purpose of traditional (durock, fiberock, etc.) cement backer board?
• What is the goal/purpose of the new Schluter material?
• Analysis/comparison of the two different approaches (point load seems like a big strike against Schluter)
• Best practice and recommendations going forward
• Relevant pointers for wall-mount backer