I am thinking of a metal shed on my concrete surfaced patio. The area where the shed will be slopes in 2 directions - from top left to bottom right (of the shed floor area) there is a drop of about 4in. I would like to build a very low 'wall' where the shed walls will be - say 1 brick high at the highest point and getting deeper according to the slope to provide a level surface to rest the garage walls on. I dont mind the fact that the internal floor will be sloping and welcome the extra few inches of height it will give me! How do I build the 'wall' to cope with the slope please.