Removing the CBU can be a pain....particularly if you installed it over a thinset morter, as is recommended by the manufacturer....you DID set it in morter, right? Oh, you didn't, eh? Well, then you just have to pull up the screws, I guess. Tiling over CBU is FAR preferable to just going over wood. You said "Hardwood." What exactly is it? Plywood? If so, yes it can be done. I've done it numerous times~~~but you better have the proper morter and know what you're doing.

Truthfully, the transition isn't that big an issue. There are marble thresholds and wood reducer strips to transition the height difference.

as is recommended by the manufacturer

REQUIRED.

I did use mortar with the board. So you think that will be a pain? Hmmm. I was leaning towards tearing it out, but now back to re-thinking.

I don't know what the wood is exactly, but I don't *think* it is plywood. I do know it is planks of wood about 3-1/4" wide and 3/4" thick. This layer is nailed onto the subfloor, which is also 3/4" thick.

The mortar I have been using is Mapei Keraset. Hopefully, that's a good one because that's what the store recommended!

I do have a solid oak threshold that will work, it's just asthetics, I guess, with such a noticeable difference in height.

Okay-- a couple of things, some good, some not so good.

First, the Keraset is fine for bedding the cement board. You don't want it adhering to the wood subfloor. However, if you're going to set yout tile with it, you're going to need Keralastic to mix it with, not water.

Secondly, cement board should not be set directly over boards. It should be set over plywood, meaning not only should the cement board come out, but the board flooring under it should, as well. Once that's out, 3/8" plywood and then 1/4" cement board goes in and then you can tile, and the tile should end up about 3/8" over the top of the hardwood. A marble threshold will take care of the transition. You CAN go with what you have, but you'd be taking a huge chance that it'd fail.

Bill....You KNOW he didn't want to hear that..........LOL

Yikes! Nope...she didn't want to hear that! But we'll do what we have to do to get it right. Luckily, it's only a 5x7 bathroom.

Is there a different product you'd recommend for setting the tile, other than the Keraset with Keralastic?

When you put it back together, consider using Ditra instead of cement board. WAY easier to use, and it only takes up 1/8".