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Transition from 5/8" greenboard to 1/2" Hardibacker

NoMSG's Avatar

Join Date: Aug 2011
Posts: 11

08-23-11, 11:25 PM   #1  
Transition from 5/8" greenboard to 1/2" Hardibacker

Long story short is that the contractor did some sketchy work in the middle of my bathroom remodel, so I'm going to finish it up myself...even though I only halfway know what I'm doing.

The contractor had taken out the floor, the old bathtub tile surround walls (rotted out), and a couple feet of drywall adjacent to the three tub surround that had bubbled up due to moisture. After that, he put in hardibacker on the tub surround walls (the area above the tub) and greenboard adjacent to it. I peeked in when he had put in 1/4 of the tile on the tub surround and found out that he didn't tape any of the hardiback seams, and the tile was being laid obviously crooked. At that point, we parted ways and he took down the tile he had just laid, leaving thinset covering some of the hardibacker.

When I assessed the situation, here's what I discovered: (1) No vapor barrier behind the hardibacker; (2) no shims under the 1/2" hardibacker, so that area sat about 1/4" below the adjacent greenboard; (3) an uneven gap of up to 1/4" between the hardibacker and the adjacent greenboard; and (4) on one of the walls where the tile was taken down, there is now thinset covering about 20 screws, making removal of the hardibacker more difficult.

Unless you guys think it's a bad idea, my plan is to remove the hardibacker; put shims in to raise it to the same level as the adjacent greenboard walls; put in a roofing paper vapor barrier; re-install the hardibacker; and somehow fill in the gap between the hardibacker and greenboard with thinset.

For this forum, here's my question:

1. What's the best way to fill in the 1/4" gap between the hardibacker and the greenboard. I'm thinking of filling it in with thinset and covering the seam with mesh alkali-resistant tape after the tile is installed. After that, I'll put three layers of joint compound over the tape, feathering it out each time.

2. It is a good idea and normal for the hardibacker to be flush with the surrounding drywall/greenboard, right?

Thanks in advance. I've never worked with wallboard or tile before, so I need all the help I can get.

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Pulpo's Avatar
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08-25-11, 06:12 PM   #2  
Why did he install 5/8 green board? What's wrong with 1/2"? Wouldn't it be easier to change the green board?

Tolyn Ironhand's Avatar
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08-25-11, 06:50 PM   #3  
I agree with Pulpo. 1/2" rock is the way to go. That is why they make 1/2" Hardibacker, because you put 1/2" rock on walls.

As far as the vapor barrier maybe you could use some Red Guard from big orange.

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