I'm building a york stone terrace. I have stacks of the traditional stuff (about 40-50 square metres) available. It's all different thicknesses and sizes. The plan is to build a low wall (12"?), fill inside with MOT 1 and sand, and then lay the flags level with the top of the wall, so that the terrace is edged by the top of the wall. The question is:

'the terrace needs a 'fall' of say 1:100 (or whatever). The wall will also require the same fall so that the flags line up with the top of it. How does one achieve this? Should the concrete foundation for the wall have a fall too or, should it be flat and the fall created with the first row of bricks. This is one of those areas of DIY where I have very little knowledge or experience.