Did you leave any room for expansion around the perimeter of the room?

Hello Kman; Thank you for mentioning the expansion space around the perimeter as I only had a gap on three sides between the sub floor and the outer framing. I am installing a foam gasket 1/4 " X 3/4 high around the perimeter of the room and along the tub.
After I have the mat leveled and ready for the ditra mat then should the foam gasket be trimmed of at this height, then the mat installed over the gasket?

Thank You
Scott

The 1/4" expansion joint should carry from subfloor through the top of the installation. You don't really need the foam gasket when installing ditra or tile, since you can cut account for the expansion joint when cutting. Foam gasket is normally used for self leveling cement to keep it from running up against the perimeter of the room.