Aquadefense over Joint Compound? - Tile Advice

[kazzos]

Hi folks. I hired a guy to hang and prep backerboard around my tub surround, so that I can start tiling it. However, when I came home I discovered that he’d used drywall mud/joint compound not only to connect the drywall to the backboard, but used it to feather down several inches to flatten out from the joints all around. Additionally, he filled in the 3/8” thick gap between the bottom of the backboard and the tub edge, also using drywall mud. When I told him I thought that was only done with mortar/thinset, he said that since we’re covering everything with waterproofing membrane, it will be fine and no water will ever reach it.

Hm.... I’m not so sure about this….

What do you guys think? Does waterproofing membrane make everything honky-dory, even drywall mud in a wet area, forever? Or should I plan on chiseling this stuff off and replacing it with mortar?

Thanks for any help you can give!

 

[Statsi75]

Uh it will probably be OK on the walls first 15 years but chisel that shot out of the Crack between tub and wall if you're caulk ever fails you will be screwd