Does anyone know of there's an actual measurement of thickness that can be classed as trenchfill? I like the option to be able to build the walls not in the centre of the trench if I have to and assume trenchfill still allows you to do that? BCO has asked to dig 1 metre deep. I would aim to finish 3 courses of bricks below ground level in case I need to split a course of bricks to get it level. And if the ready-mix delivery leaves us a bit low is there a point below which I'll have a problem? Cheers.