QUESTIONWe have terra-cotta tile (about 3x5 inches) on a flat roof that is also a roof-deck, in Mexico, that leaks mainly through a series of cracks across the floor.
I understand the best would be to rip up the tile and seal it with a proper waterproof System and re-lay the tile. Does it make sense to just cover it with some sort of decking material?
Do you have a recommended system for either or both approaches?
ANSWERANSWER - It is possible to install tile over tile if the existing tile is in good condition. If the existing tile is cracked then the new tile installed over it will crack. In order to repair the cracks you need to determine what caused the cracks so you fix the problem rather than try to fix the symptom of the problem.
Waterproofing the roof/deck is a critical step; particularly if there is occupied space underneath. Again you don't want to try to fix the symptom, you want to figure out why is it leaking and what caused the leak. The only way to do that is to remove the existing tile. Properly prepare the substrate so it is stable and sturdy; without deflection. Then you want to properly waterproof the deck.
To waterproof the deck you need to first determine how will the water drain from the deck both at the tile surface and at the surface of the waterproof membrane. If there is a drain on the deck then the waterproofing has to slope towards the drain and clamp into it. The drain weep holes have to be open and protected so water beneath the tile has a way out. If the deck doesn't have drain and water drains off of the deck, then the waterproof membrane has to slope that way at 1/4" per foot. Make sure the waterproof membrane flashes up the perimeter walls so it water can't migrate through the walls into adjacent areas.