Hi we are in the process of looking at getting our rooftop solarium re-tiled. The property is over 30 years old and some of our tiles are cracked at this stage. Various quotes have been received both with and without the membrane under the tiles and the prices are wildly varying. They are talking about tiling over existing tiles also. My question is if they are tiling over the existing tiles is an additional membrane necessary. Last thing I want is water coming through my ceiling but I don't want to be paying money un-necessarily either. Thanks in advance for any advice.
Helga