we have with our neighbours,a tiled patio, with a foundation of about 6 inches of concrete,the boundary is weldmesh fencing fastened to metal 50mm dia fence posts. we want to remove this and build a 1metre high single block wall between us (fence and posts rusting). ....can i build on top of the tiles ,as foundations are already in place , or do i need to remove some tiles to build straight on to the concrete founds .....thanks
Assuming you are referring to quarry tiles or something similar it would be unwise to build direct onto them because the bottom of the wall will be be extra wet especially when it rains. Remove a strip of tiles where the wall will be.