I'll go through your list and expand a bit on the materials you mentioned and how they may relate:

Cement board: If using Kerdi, I recommend a TRUE cement board like Durock or Wonderboard. If you have to use a fiber-cement like Hardie, no worries...it's just that Hardie tends to wick moisture from the thinset faster than the other two boards.

Cement board with a topical membrane: Yes, you can use Kerdi, RedGard, Hydroban, etc, over cement board. Kerdi, being a sheet membrane material, can go right over the backer board. With the "liquid paint-on membranes" like RedGard and Hydroban, if the board was installed with excessive gaps the joints and corners may have to have reinforcing fabric installed so the membrane can bridge those gaps. If you want more info, read the manufacturer's installation pdfs for those memebranes.

Thinset: Although you didn't mention thinset, be aware that Kerdi can have different thinset restrictions than the other membranes. Sometimes Kerdi requires an unmodified thinset for warranty coverage instead of what most installers will use, a modified thinset. Again, you'll find more info in the Kerdi installation instructions.

Tile with epoxy grout. No worries there. There are complaints about epoxies yellowing over time. It's a "chemical thing" inherent to epoxies. I'm not going to say it's a problem, but as some have complained, it's at least a consideration. You may notice it if you were to go with a "white" white epoxy. Yellowing typically isn't seen with non-white epoxies. Again, the yellowing issue isn't a hard and fast truth that always occurs with epoxies. It's simply something to consider.

Seal: There's no need to seal porcelain tile, it's non-porous. There is no need to seal an epoxy grout. It's non-porous.

Added info: If you're going to use Kerdi, and you're going to use a manufactured base, have you looked at the Kerdi Tray? It's part of a comprehensive shower system from Schluter (the company that manufactures Kerdi).

If you're interested in Kerdi Board, then you won't need cement board in the walls. Kerdi Board will be the "backer board" and the "membrane". You probably know that, but I thought I'd toss it out regardless.

If you can't find a manufactured base: Most showers I've done are custom-sized showers. I'll do a sloped floor out of deck mud and set a flanged drain in that mud base. Both Kerdi and Laticrete make flanged drains. You then Kerdi the entire shower (Kerdi Drain) or Hydroban the entire shower (Laticrete Flanged Drain). Meaning that if you can't find a manufactured tray, you can still use either topical membrane (Kerdi or Hydroban) on your shower floors and walls.

As to alternative fourth-party manufactured pans to use with these topical membranes, you generally want to stick within a manufacturer's product line IF you are using Wedi, Kerdi, or Hydroban. Wedi with wedi, Kerdi with Kerdi, Laticrete with Laticrete, etc.

The one exception I'll toss out is the Kerdi Drain. It can be set in a sloped mud floor and you can then waterproof the entire shower with Kerdi membrane or with Laticrete's Hydroban. Laticrete will warranty Hydroban installed with a Kerdi Drain.

To source products, if Home Depot Canada doesn't offer them, they may be able to special order them. However your better bet may be to go to the manufacturer's website (schluter.com fo Kerdi, etc), select the dealer locator, enter your postal code, and see which dealers in your area offer their products.

Good luck!

Thank you mongoct. I appreciate that you took the time to explain these things to me. I am truly clueless on any kind of DIY.

I think I understand a little better now. It goes in this order: backer board, Kerdi membrane, thinset, tile and grout.

I plan to remodel 3 bathrooms.

For the ensuite, I think I will be using some stone on the floor and porcelain tiles on the walls. I guess I will be using the Kerdi pans here.

I think I will go with the Kerdi membrane. Some folks mentioned that the Kerdi boards are difficult to work with for tiles.

So, I spoke with an installer today, they said they use the blue drywall. Is that the same/similar to Wonderboard?

Thanks for mentioning that the Kerdi requires unmodified thinset. The fellow I spoke to said they will be using modified thinset. Will this be a problem other than warranty?

For the other two bathrooms, I was thinking of using the Kohler shower base K-9948 and the Hytec Kendale Receptor ACR3794N. If budget permits, I plan to tile the shower walls using similar water proofing methods as the ensuite.

I asked about epoxy grout and was told that it sets too quickly. They prefer to use Mapei Flexcolor CQ. Any comments or thoughts on this product mongoct?

Blueboard is a gypsum-based backerboard that is designed to be covered with a veneer coat of plaster. Think of is as "drywall" with a different colored paper. The blue paper has certain qualities that provide a good bond with plaster. It's completely different than a cement board like Durock or Wonderboard, but it serves the same purpose. Schluter's allows "drywall" to be used as a backer for Kerdi, their tech department told me years ago that blueboard is a suitable substrate for Kerdi.

Modified versus unmodified thinset with Kerdi? Kerdi can usually be adhered to backer board or a substrate with a modified thinset. But when setting tile on Kerdi, Schluter requires an unmodified thinset.

Thinset is based on portland cement. Portland cement cures via a chemical reaction, it does not need to be exposed to free air.

Modified thinset are slightly different. The polymer additives in modified thinsets need exposure to free air to cure and to create a full-strength bond. The modifier simply "dries". The thinset will not see much air when sandwiched between Kerdi and tile, as both are obviously impervious to air penetration.

There are specialty unmodified thinset that are normally used with Schluter's membranes like Kerdi. Most of the typical off-the-shelf umodified thinsets sold in the box stores are a low-quality product.

If they use a lightly modified thinset there should be no problems with standard-sized tiles or smaller. I'd be wary of using a highly modified thinset with standard-sized tiles, or using any level of modified thinset behind a large-format tile.

Mapei Flexcolor CQ is a fairly new grout, it just came out earlier this year. It should work fine for you. No need to seal it.

I'm making notes mongoct.....lots of it.

How can I tell if the thinset is lightly modified vs a highly modified version. I am using 12x24 porcelain tiles on the walls. Or what would be an acceptable (brand name) unmodified thinset for kerdi.

On the shower floors, you had previously said to use the same brand. So Kerdi tray it is. Would you please share with me what goes on the tray and in what order.

Thank you!

An example of a "lightly" modified thinset would be "Versabond" from Home Depot.

Good examples of unmodified Kerdi-Friendly thinsets would be "DitraSet" from Bostic, but is pricey. I generally use Laticrete's "317" in white.....runs about $10 a bag and can be found at Dal TIle....

"How can I tell if the thinset is lightly modified vs a highly modified version."

You can go on their websites and take a look. They can be confusing at times.

But overall, I agree with Stonetech.

You'll find most manufacturers have three thinsets in a series. Stonetech mentioned Home Depot's Custom line of thinsets. Custom's unmodified MasterBlend is about $5 a bag, the lightly modified VersaBond is about $15 a bag, and the highly modified FlexBond is about $30 a bag. Give or take a few dollars per bag.

If you or your builders buy Custom's MasterBlend, it's really only good for one thing: Returning it to the store. Seriously. Or building a levy if you're expecting a flood. Seriously. Don't buy it.

Custom does make an unmodified "Uncoupling Mat Mortar" and that's supposed to be a good product, but I've never seen it stocked anywhere.

As Stonetech mentioned, Laticrete's 317 is good, their 272 is a bit better. But either is fine as an unmodified. Same with Bostik's Ditraset.

If Mapei is sold near you ( I think Lowes sells it), their unmodified KeraBond is a fine product.

Custom, Laticrete, and Mapei are the three big ones around me. But I'd only use the unmodifieds from Laticrete or Mapei.

When you get into modified thinsets, I have no real negative issues with anyone's thinsets.