I have a customer thats asking me to do a flooring job for them, here is the issue there is carpet glued down to a existing tile subfloor, owner wants me to do it the least expensive way possiable soi thought that would be to isntall the new porcelin tiles over the existing cermaic tiles but what is the exact procedure here do i need to sand the tile floor down will this even give a proper bond for the thinset, thanks in adavce