I would like to build a raises seating area in one corner of my garden. The floor will be decked, but I want the sides to be rendered brick flower beds. Imagine something like this : Does the block work need to be two thick, or would I get away with a single. I expect the planting area to be much narrower (about 15cm) so won't be planting trees or anything. Excuse me if I have used the wrong terminology, but any help will be much appreciated. Thanks Anand