Durock or Hardi backer?

I interviewed a tilesetter yesterday and asked him which he uses and he prefers Durock. I also interviewed another contractor who said that Hardi board is porous and Durock is not. I told them both that since we have a tub, I want Kerdi used to make sure there is no moisture problems. They both disagreed about using Kerdi. What about us DIYing the Kerdi part? Do we put it up before Durock or after Durock? Would you put Kerdi on the floor? They want to use cement board on the floor too and say this will take care of the creaking floor boards.

on the web sites of the manufacturers you will get the information straight from the horse's mouth. Using a search engine you can find the products' manufacturers.

You have two big questions.
1.) What to do about your wooden subfloor under the new tiles you want to lay
2.) What to use to build the walls and ensure you have the waterproofing you want.
These have been answered for th emost part over at your other thread https://terrylove.com/forums/showthread.php?t=11751 It is a good idea to repost here in a new thread just to be sure about these questions. .

There are four different shower membrane methods. They all work.

Kerdi is a current sponsor of the JBF forum which people refer to here. That forum uses the same software to run it, so it looks the same.

David

You MUST resolve the squeaking subfloor before you install tile. It always requires a layer of plywood on top of planks minimum of 1/2" - then either cbu or a membrane, your choice. As previously noted, if the floor joists are not strong enough, nothing you do on top of the subfloor will prevent tile and grout from cracking - nothing. Also, as stated, if you use Kerdi, it always goes just under the tile - the idea is to prevent moisture from penetrating very far, which makes the shower dry out faster. Unless you regularly have water fights in the bathroom, most people don't worry about trying to put a waterproof membrane down on the floor. Ditra is a membrane designed to help prevent cracking tile (in place of cbu) that CAN be made waterproof if you use Kerdiband on the seams, but unless you run it up the walls, moisture still can get under the floor. Rarely is it needed. Maybe in a restaurant kitchen where they might hose it out on a regular basis.

All the pro tile layers I know will only use Durock.

It is often a supply thing...what does your local preferred supplier carry. They each have the benefits and deficiencies. Hardi doesn't crumble as easily when you have to cut it or nail or screw near an edge. It can't be used in exterior applications. So, if you were going to carry one product for everything, it may not be the choice, but for what it does, it works fine, and some prefer it.