# help on sealing hardibacker joints



## akbeard (Jan 4, 2010)

i may have oopsed on my hardi-backer joints. i was told to use the mesh tape and seal with joint compound and then prime the compound before i tile my shower. now i read that i should have used thinset to seal the tape. i don't have the tile on yet, what can i do to fix my problem or is it ok how it is. i also do have a vapor barior behind the hardi-backer. i was told this by a tile installer so it could be ok, but any advice would be great!


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## Just Bill (Dec 21, 2008)

Drywall mud is not moisture resistent, thinset is, thus the reason for using thinset. The reason for sealing the seams is to reduce the possibility of the joint transmitting thru to the tile, and to make it watertight. If the tile grout joints NEVER leak, you will not have a porblem, but.........??????


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## akbeard (Jan 4, 2010)

what would be the best way to fix it? i could use epoxy grout, paint on sealer, or do you think that since i primed the compound i am good to go?


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## firehawkmph (Dec 12, 2009)

Ak,
Just curious, who told you to use joint compound and paint the hardi backer? I would be tempted to pull it down and start over. You have one chance to do a tile shower right. The hardi backer is probably the cheapest part of the job. The last tile shower I did was over $6000.00. I wouldn't want to have to take it apart once the tile was up. You may get away with it, but anymore, I don't want any of my projects to end up on Holmes on homes, if you know what I mean.
Mike Hawkins


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## ponch37300 (Nov 27, 2007)

I don't know if this would solve your problem but red gaurd is a water proofer that you roll on and it dries like a rubber. I have used it to waterproof my shower joints after I used tape and thinset.


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## Kevin M. (Nov 26, 2009)

akbeard said:


> what would be the best way to fix it? i could use epoxy grout, paint on sealer, or do you think that since i primed the compound i am good to go?


Thinset and durabond 90 are pretty close in chemical composition. Thinset will adhere to chemical compound like durabond 90. If you used joint compound from the bucket it is an evaporation product not a chemical dry product. Either way an oil primer will work as a bonding property for the thin set. 

Kevin


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## Itsdanf (Jan 29, 2009)

I'm with Ponch: Roll on Red Guard. It makes a membrane that's waterproof, and you can tile directly onto it.


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## akbeard (Jan 4, 2010)

thanks for all of your help. where do you get the red guard? will it be at one of the box stores or is this from a tile or specialty store? 

kevin mentioned that since i used an oil base primer i might be ok with that.

will the thinset stick to latex paint also? i was planning on tiling one full tile (6") past where the shower door and the hardi-backer end, and i already painted that area over the primer. i thought i was doing a pretty good job until i found this forum! i really apreciate all of the advice from everyone.


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## Blondesense (Sep 23, 2008)

I believe Home Depot carries it. Not sure of who else.
If you look online note the spelling on the bucket. It is often misspelled.


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## ponch37300 (Nov 27, 2007)

Home depot carries redgard http://www.homedepot.com/h_d1/N-5yc...splay?langId=-1&storeId=10051&catalogId=10053

I don't think you will have a problem tiling a row past your backer board. 

Hopefully a tile guy will chime in and give some advice.


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