I would like to replace the fence between myself and next door with a 2m high wall. I dont want the wall to be too thick as my garden is only 5mx5m ( a yard really). The advice I can find online suggests that a 2m high wall needs to be 300mm wide using blocks. This seems quite wide and if i do that on both sides of the garden im really reducing the size of the garden. Does anyone have any other ideas or experience in this area. Any help would be much appreciated.