Tiling Question - Hardiebacker Joints

longhorn_1998

17 years ago

I am hoping Bill Vincent and the other tiling experts on the forum can help with a question about Hardiebacker joints.

I hired a contractor to frame a new shower and install the CBU panels. I have the responsibility for preparing and tiling the surface.

I am concerned with the size of the gaps between the panels in the corners. Instead of the desired 1/8", they measure about 1/2". In addition, the notched corner of the panel where it meets the shower curb is set too far back, with about 1" between the edge of the panel and the edge of the curb.

Do I need to have him replace these and size new ones correctly? Or, can I just fill these gaps with thinset to form a continuous surface?

In case this is relevant, I'll mention there is no vapor barrier (contractor didn't seem to think it was necessary) so I plan to apply Redgard to the CBU prior to tiling.

Sort by:Oldest

Comments (6)

bill_vincent
17 years ago
Have him reinstall the panels. Let me ask you-- is there any kind of vapor barrier behind the hardiboard?
longhorn_1998
Original Author
17 years ago
Thanks, Bill, for the reply... There is no vapor barrier behind the Hardiebacker. But, I had gotten the impression from other forum threads that that was OK as long as I apply Redgard over the Hardiebacker. Do I need both?
Related Professionals
West Palm Beach Kitchen & Bathroom Designers · Bloomington Kitchen & Bathroom Designers · Moline Kitchen & Bathroom Designers · Montréal Kitchen & Bathroom Designers · Baltimore Bathroom Remodelers · Des Moines Bathroom Remodelers · Amherst Bathroom Remodelers · Albany Bathroom Remodelers · Providence Bathroom Remodelers · London Bathroom Remodelers · Roanoke Tile and Stone Contractors · Kearney Tile and Stone Contractors · Clearlake Tile and Stone Contractors · Ontario Tile and Stone Contractors · Casper Tile and Stone Contractors
peteinsonj
17 years ago
Keep in mind that tiles & grout are NOT waterproof! They will let moisture seep behind them --

SO -- the hardibacker installed as you describe, with wide joints and no taping -- does not work!

Redgard ought to do the job, though, as I understand... (or moisture barrier behind.
MongoCT
17 years ago
My problem with this is that Redgard and other topical membranes need to be applied over a proper substrate.

There are limitations to some of these membranes...some are just "waterproofing" membranes, not all are "crack isolation" membranes, etc, etc. Some need reinforcing fabric to span cracks.

What I'm getting at is that these are wide gaps. 1/2" to 1" wide. Will they be properly taped and mudded so the mud doesn't crack as it shrinks? Or cracks down the road? If the person who applied the backer board this sloppily is going to pack the cracks, I'd venture a negative reply would be in order.

Also for gaps that large, even AFTER they are packed with mud, I'd want to see reinforcing fabric used to help aid in keeping the topical membrane intact over those packed joints, especially in any corners.

Again, this guy doesn't come across to me as even knowing about reinforcing fabric.

Or building showers in general, since the barrier was left off the walls prior to mis-hanging the cement board.

Building a proper shower is simply A-B-C-D construction. Too many people skip steps and end up with C-R-A-P instead.

Mongo
bill_vincent
17 years ago
What Mongo said. The Redgard is fine...... without those big gaps, which is why I asked if there was a vapor barrier behind the hardiboard, because if there was, you could fill those gaps with thinset and be fine. Being that there's none, though, those gaps must be closed up.

Again, have him tear it down and do it right.
longhorn_1998
Original Author
17 years ago
Great--thanks to all for the confirmation.