Schluter KERDI Rgroup_18524 or with a white pad

or with a white pad if using a polisher

the test is negative

You could sleep on this and feel completely comfortable

it's money in your pocket

Schluter KERDI Rgroup_18524 or with a white padNon toxic, waterproofing membrane for tile and stone Schluter KERDI is a pliable membrane designed to waterproof walls and shower floors prior to installation of tile or stone. Made of 8 ml thick polyethylene in Germany with zero VOCs and no odor, KERDI is covered in both sides with a fleece webbing to anchor the membrane in ceramic tile thin set mortar. Use it over regular sheet rock. There's no need for special green boards or waterproof drywall.