I will ask my DH and get back to you! :-)

He installed the Hardibacker and then applied Hydroban in/on one shower surround and two tub surrounds, so would be better able than I at answering your questions.

Thanks cat_mom!

The hydroban is fine. Just grap a small paint roller, and git rollin!!

One thing-- although it's not required, I like to use the 6" fiberglass cloth over all the inside corners and seams between the sheets of cement board.

Thanks Bill!

DH has been inmtgs all week so hasn't had a chance to look at this thread. From what I can tell, DH followed the steps you listed. Just wasn't sure about step #2. I am sure Bill wouldn't steer you wrong!

I don't know if DH used fiberglass cloth or ? at the inside corners and seams. I do know he used thinset instead of joint compound for the seams.

Cat_mom, thanks for remembering, sometimes my memory is about 2 seconds long:)

Mine, too!

I will try to ask DH later if there's anything you missed (or that Bill might not have pointed out explicitly). Bill was very helpful in answering DH's questions when he did our bathrooms, so I doubt much if anything hasn't already been addressed.

If I don't get to ask him tonight, I promise to do so before the week is out!

Cat thanks :)

DH reminded me that he furred-out the studs, and then installed the Hardibacker over the tile flange (as described in this thread):

http://ths.gardenweb.com/forums/load/bath/msg1120511823883.html

As mentioned on the thread I linked, this was suggested by our tile guy as his preferred Hardibacker installation technique (which I think Bill okay-ed on that thread).

HTH!

I don't know if DH used fiberglass cloth or ? at the inside corners and seams. I do know he used thinset instead of joint compound for the seams.

If you use the FG cloth and embed it in Hydroban, there's no need for thinset OR joint compound.

As mentioned on the thread I linked, this was suggested by our tile guy as his preferred Hardibacker installation technique (which I think Bill okay-ed on that thread).

YUUUUP! :-)

Then he used the thinset, but not the FG cloth.

You would be proud of DH's work, Bill. :-) I know I am! Thanks again for you help and advice!!!

Thanks you guys, this is just the info I need. Cat that link helped clarify for me a lot!

So Bill, it sounds like I can either come down TO the top of the flange like plan #1. OR, fur out the studs and bring the Hardiebacker down over the flange to hover over the horizonal surface of the tub like plan #2.

So now, where to caulk with silicone?

1) If I come to the top of the flange is it ok to caulk at that junction of board and top of flange? Like this illustration:
{{gwi:1450727}}

2) If I fur the studs, do I caulk at the junction of the board that is nearly resting on the horizontal surface of the tub? Like this illustration:
{{gwi:1450729}}

3) Which technique of fitting the hardiebacker is better? I think #1 would be much easier.
4) Need clarification on the caulking to seal hardiebacker to tub.

Thanks for your time.

I wouldn't bother at all with caulk BEHIND the tile. The biggest thing is to fill that big gap at the bottom of the cement board, so you don't have a hollow spot behind the tile, making it easy to snap off the bottom of the tile. That can be accomplished with a stiff thinset. You can then waterproof over the top of the thinset when you waterproof the hardiboard. Save the caulking for between the tile and the tub.

Thanks Bill, makes sense to me.