Help! Hydro Ban patch over hot mop?

[Mer1]

I need your professional advice whether a Laticrete Hydro Ban patch in of a drain over hot mop will work. My contractor neglected to install my new drain in a high end Master Bath redo. When brought to his attention he drilled out the tile and the old drain. Installed the new (cast iron) drain with a Hydro Ban patch (with mesh) 12 inches out over the hot mop. Laticrete says Hydro Ban will not bond to the hot mop. Additionally they say the rustproof film on the cast iron drain must be removed for the Hydro Ban to stick. That was not done.

Contractor says manufacturer limits their liability by limiting the substrate list and that it did adhere, as well as it did bond to the cast iron. He wants to do a 2 day flood test (tile is not grouted yet) to appease me. I am skeptical that this is a perfect predictor of waterproofing down the road.

 

[Jadnashua]

The manufacturer is the arbiter on any suitability (long-term) use of their product. While it may be working today, it seems, based on what the manufacturer of the product has said, it won't long-term. The goal should be a long-term solution. Builders come and go, and it's rare that they offer more than a 1-year warranty (and even that may be useless if they move or change their business name). What about 5-years, or 10-years down the road?

IMHO, while common in CA, I'm not a particular fan of hot mopping for waterproofing a shower. While it can last a long time, there are other tested methods of building a shower that are, IMHO, significantly better.

You might ask the same question over at www.johnbridge.com, but IMHO, if the manufacturer of the product says it will not work, I'd believe them over the contractor. CI tends to get a coating of rust, paints don't stick to rust. Paints don't tend to stick to asphalt well, either. The flood test is going to show you today...you want many tomorrows. It could have been fixed if he called back the hot moppers (IMHO) and then, there wouldn't be any dissimilar materials you have to worry about compatibility between. It's vitally important that the weepholes in the clamping drain be kept clear, or moisture will build up underneath the tile. This may not cause a leak, but may mean the grout never dries, which means it's easier for mildew to form.