I would like to talk to the vendor who is willing to tile over cultured marble and warrant the work and also, gives out this advise as sound construction approach that homeowners need to consider. I want to learn more about the basis for this improvement advise.

A bathroom or kitchen remodel is a 20 year to 40 year improvement that effects the valuation of your home. Why would you begin a valuable improvement with any process that is less than an accepted "industry standard" methodology and nationwide adapted construction practice for how to proceed for the work that needs to be done? Of course everyone appreciates clever techniques and discounted materials. Everyone wants things to be done effectively and skillfully but, not PAY top dollar. Believe me as a designer consulting on the finish look I get tired of all the budget money going to electrical, plumbing and structure but, you must not skimp on a structure's basics. Tubs and showers (important basics) have to be built and remodeled correctly or you will be revisiting the same work at greater expense sooner than you think. Do it right and skillfully and it will serve your family for a long, long time.