We are remodeling our bathroom and getting conflicting info from contractors about tiling above a fiberglass tub. I would like to have tile above the tub for the shower surround. One contractor says its OK to tile above a fiberglass tub. The other says the tub needs to be cast iron if using tile because there would be no give in the tub thus eliminating cracking in the seal between the tub and the tile. The second view seems reasonalble but I would like to get others thoughts!