Questions about backerboard for tub surround - TilersForums.com

[longtimealaska]

I am installing Hardie backerboard for a bathtub surround and plan to tile the tub surround with 12 x 12 ceramic tile.

1. The hardie backerboard is water resistant, not waterproof, so I was planning to waterproof it with Aqua Defense.
2. Installation instructions for Hardie backerboard say to fill the 1/8 inch gap between the boards and cover the seams with thinset and embed alkali-resistant fiberglass tape into the thinset. Hardie does not address using waterproofing.

My question: Do I apply the Aqua Defense after I apply thinset and tape so the thinset is also waterproofed or do I apply the Aqua Defense to the hardie backerboards before I apply the thinset?

It makes sense to me to do the seams with thinset and tape first and then waterproof it.

Some help with this would be greatly appreciated.

 

[Jpvvpj]

Yes thin set tape everything and last step water proof.. Hardie backer is something we never use ,, it brakes very easy if you nail or screw next to the edges and you always have to fasten the board close to the edges . Also there is a dusty powder that is always on the board even after sweeping it so I would get a scrap and paint some water proofing on it and let it cure then see how easy it will peal off. May work great or it may peal right off . Better to know ahead right ..